سید وحید اسلامی

Salinity stress is an important abiotic stress threatening the production of cotton in arid and semi-arid regions of the country and the world, which can be reduced by the proper use of organic materials. Cotton is the most important fiber product, which is widely cultivated for agricultural and industrial purposes in temperate and hot regions of more than 15 countries of the world. Although cotton is known as a salinity-tolerant plant, not only is the resistance to salinity limited in this plant, but different stages of development also show different reactions to salinity. One of the effects of stress is disturbing the nutritional balance in the plant. Proper nutrition during times of stress can partially help the plant deal with various environmental stresses. In this regard, by using fertilizers containing micronutrient elements, firstly, plant yield increases, secondly, increasing the concentration of these elements in agricultural products plays an important role in improving the quality of food consumption. Using organic fertilizers, especially organic and animal manure such as humic acid, can improve the performance and performance components of different products under stress conditions.

To study the effect of manure and humic acid on some of the physiological qualities of cotton under salt water salinity stress, an experiment was conducted as factorial split plots (factorial split plot) in which different levels of irrigation water salinity at three levels (2.5, 5.5 and 8.5 ds.m-1) as the main factor and two treatments of manure at two levels (0 and 20 t/h) and humic acid at two levels (0 and 200 gr/100 kg of seeds) as sub-factor in 4 replications in a farm located in Boshrouyeh city in 1398 years. The software SAS (V9.1) and Excel were used to analyze the data and draw the figures. Means were compared using the FLSD test at a 5% probability level.

Analysis of variance results showed that the simple effects of three experimental factors (salinity stress, manure, and humic acid) were significant on all studied traits (on the relative water content, Electrical conductivity and membrane stability, chlorophyll a and b contents, and proline content). With increasing salinity level, increased proline content (286.5%), membrane Electrical conductivity (4.2%) and carotenoids (88.79%) and decreased chlorophyll a (20.7 1 %) and b content (39.38%), relative water content (23.16%) and membrane stability (13.54%). The application of animal manure and humic acid increased the relative water content, membrane stability and chlorophyll content under stress conditions, which indicates the modifying effect of these fertilizers in reducing the adverse effects of salinity stress. The interaction effects were significant, too.

The results of this research showed that the use of water with high salinity, such as salinity of 8 ds.m-1, caused significant changes in the physiological traits of the plant, including relative leaf water content, membrane stability, membrane electrolyte leakage, chlorophylls, and proline. With increasing salinity levels, the amount of proline, membrane electrolyte leakage, and carotenoid increased, and the content of chlorophyll a and b, relative water content, and membrane stability decreased. The application of animal manure and humic acid increased the relative water content, membrane stability, and chlorophyll content under stress conditions, which indicates the moderating effect of these fertilizers in reducing the adverse effects of salinity stress. Considering the positive effects of using organic fertilizers in this experiment, it is recommended to test and investigate the use of humic acid during the growing season in addition to the use of animal manure before planting and the use of humic acid in bulk Thus, it is suggested to use humic acid and animal manure in cotton cultivation to adjust the salinity levels.

Increasing soil carbon, both globally and on a farm level, has been considered as a fundamental strategy to reduce atmospheric carbon dioxide and increase soil productivity. Because agricultural ecosystems cover 11% of the earth's surface and wheat is one of the three most important grains in the world, any study on increasing soil carbon through land management and organic additive management can lead to a better understanding of our potential for soil improvement, ecosystem services, higher biomass yields, nutrient recycling, potentially increasing agricultural and ecological productivity. Crop rotation significantly affects the sequestration capacity of atmospheric carbon dioxide, and the change of cropping systems from fallowing to continuous cultivation can affect the rate of carbon sequestration in the soil through the introduction of more organic carbon. Also, managing the use of fertilizers, especially nitrogen, will not only increase crop yields, but also increase carbon sequestration as a secondary benefit to the land. Due to the alkalinity of most soils in arid and semi-arid regions, the addition of organic matter reduces soil acidity and improves plant growth conditions, increases the ability to absorb elements such as phosphorus and iron, moreover has a positive effect on increasing biomass production and carbon sequestration.

This study was conducted to take advantage of a set of desirable crop measures in diverse production systems with the aim of improving the chemical properties of soil and carbon sequestration with a focus on wheat during the two cropping years of 2018-19 and 2019-20 in a farm in Taybad plain. In this study, the factor of the cropping system in four levels (wild rocket-wheat, fallow-wheat, mung bean-wheat and corn-wheat) and the factor of nitrogen fertilizer levels (100, 50% and without nitrogen fertilizer application) were implemented in a randomized complete block design as factorial with three replications. Soil chemical properties such as acidity, organic carbon, total nitrogen, available phosphorus and iron were measured.

The highest amount of acidity was observed in corn-wheat treatment with 50% nitrogen fertilizer supply and the lowest amount of acidity was observed in wild rocket-wheat treatment with 100% nitrogen fertilizer supply. The study of treatments shows that wild rocket and mung bean showed the best results in increasing soil organic carbon and carbon sequestration. Corn less than were able to increase soil organic carbon, although with increasing nitrogen fertilizer supply in the corn-wheat cropping system, organic carbon improved compared to the control treatment. The results also showed that wild rocket-wheat treatment with 100% nitrogen fertilizer supply experienced the highest increase (56.7%) and corn-wheat treatment with 50% nitrogen fertilizer supply experienced the lowest (21.4%) increase in soil organic carbon. Soil nitrogen was also significantly affected by the increase of soil organic carbon mainly in two treatments of wild rocket-wheat (25.6%) and mung bean-wheat (17.9%) in conditions of 100% nitrogen fertilizer supply, while fallow-wheat and Wheat maize without nitrogen fertilizer showed the highest reduction in soil nitrogen content of 15.3% and 20.5%, respectively. Phosphorus and iron levels also increased in all treatments. The results of trait correlation also showed that reducing acidity in alkaline soils is the key to success in increasing plant access to phosphorus (r = -0.37 **) and iron (r = -0.33 **). It seems that the most important factor in the improving farming practices, which leads to an increase in organic carbon and consequently soil fertility, is the removal of fallow and continuous cultivation of agricultural lands.

The results showed that soil organic carbon increased in all treatments and led to increased carbon sequestration and improved soil chemical properties. The results regarding nitrogen also showed that non-use of nitrogen fertilizer in all cropping systems reduce or stop the increase of nitrogen and the need for optimal use of nitrogen fertilizer even in the case of using cover crops or legume as a nitrogen stabilizer. Reducing acidity in alkaline soils is the key to success in increasing plant access to phosphorus, although the capacity of soil organic carbon to retain phosphorus and iron in the soil should not be underestimated. Also, cropping systems affected by the type of crop rotation had different effects on soil properties. It seems that in addition to determining the quantity and quality of plant residues, plant rotation will have a different behavior on the concentration of soil elements depending on the amount of harvest of each nutrient.

In order to investigate the compounds and anti-injury properties of the medicinal plant Anghuzeh on the germination of the seeds of two weeds, red root crown and wild oat, a research was carried out in the form of 4 separate experiments in 2022 in the seed technology laboratory of the Faculty of Agriculture of Birjand University in a factorial form in a completely randomized design in three replications. were implemented The factors of the experiments included two types of angouzeh juice (bitter and sweet) with concentrations of 100, 200, 400, 800 and 1000 micrograms/liter. Also, a control (zero concentration of the stimulus) was considered next to the main experiments. In the first two experiments, the ethanolic extract was used and in the next two experiments, the aqueous extract of angouzeh powder was used separately on two weeds. The results showed that the use of aqueous extracts of both types of bitter and sweet angoose more than the ethanolic extract decreased the germination characteristics of the seeds of both weeds, and the concentration of 1000 µg/liter of both types of angoose juice in both extract. In all the experiments, the germination speed of the seeds of both redroot pigweed and oat plants was less strongly affected by the concentrations of angouzeh juice compared to other traits. In general, the results showed that the aqueous extract of both types of bitter and sweet angoose had a greater effect on the germination characteristics of the seeds of two types of weed.

Oilseeds are very important as the raw material for the production of vegetable oil (one of the basic needs of the society in the food field). Therefore, achieving any success in increasing the amount of production and supplying as many of these products as possible to meet the domestic needs of the country is considered a valuable and great success. Safflower, with the scientific name Carthamus tinctorius L., is an annual long-day plant from the chicory family. Wild mustard (Sinapis arvensis L.), which is also called Brassica kaber in some literatures, is one of the most important weeds belonging to the Brassicaceae family. Competition can perhaps be considered the most important biological interference factor effective in determining crops productivity.Effective management of weeds in agricultural systems is very decisive. Extensive and repeated use of herbicides has led to the emergence of resistant weed biotypes, which has often increased the cost of control. It has also caused some concerns about the negative environmental effects of herbicides. When the competition is for light, the competitive ability of the species is first determined by the morphological traits. The response of crop height to weed competition is related to the density and intensity of competition and the type of weeds and can be positive or negative.

An split plots experiment based on randomized complete block design with three replication was carried out in the Research Farm of University of Birjand during the 2018-2019 cropping year. The treatments include four level of phosphorus fertilizer (0, 25, 50 and 75 kg P 2O5 ha-1) as the main plot and the four wild mustard densities (0, 7, 14 and 28 pl m-2) as subplots. Plant growth characteristics were measured from 150 to 210 days after planting (DAP) in five stages at 15-day intervals. Also, at the harvest maturity, the yield and yield components of the crop were determined.

According to the results, the highest (35.48 g m-2) and lowest (28.23 g m-2) safflower leaf dry weights were obtained from control (no-mustard) and 28 pl m-2 mustard densities at 165 DAP, respectively. The highest (1.67) and lowest (1.19) leaf area index of safflower were achieved at 210 DAP using 25 and 50 kg P 2O5 ha-1, respectively. Based on these results, it can be concluded that the most effective level of phosphorus on the improvement of safflower growth traits (e.g. leaf area and dry weight and stem dry weight) and its competitive ability was 25 kg P2O5 ha-1, although the its effects were not significant for many traits, and as phosphorus levels increased, the competition shifted more in favor of wild mustard. In accordance with these results, and probably due to luxury consumption by weeds, it has been observed that when weed density is high, adding fertilizer leads to superiority of weed growth over crop (Blackshaw et al., 2008). Also, the highest leaf area index of mustard (0.63) was obtained at a density of 56 mustard pl m-2 at 165 DAP and the lowest one of (0.26) was observed at a density of 14 pl m-2 at the same time. It was also observed that the height and leaf area index of wild mustard were the highest in all measuring stages at higher weed densities, indicating the competitiveness of the weed. The increase in weed density had a negative impact on the safflower, although insignificant in many cases, which could be the result of the competitive effect of mustard for resources such as radiation and nutrients (Wright et al., 1999).

In general, the increase in weed density had a positive effect on the yield and its components in wild mustard and a negative effect on the safflower, and under these condition, the application of more than 25 kg P2O5 ha-1 does not have a positive effect on the crop. Thus, it seems that the revision in weed management and the use of fertilizer as an agronomic strategy can be effective in reducing the crop losses caused by the presence of high densities of weeds (Clements et al., 2014).

 Cotton (Gossypim hirsutum L.) has a special position as one of the most important crops in the country. Considering that salinity stress is one of the most important stresses, it threatens cotton production in arid and semi-arid regions of the country and the world, it is possible to reduce the adverse effects of salinity stress through application of organic fertilizers (manure and humic acid). In addition, Organic inputs can guarantee both agricultural production and nature conservation. The current approach is to employ the organic compounds like manure and humic acid (that are cost-effective and eco-friendly) as an appropriate substitute for chemical fertilizers.

This study was carried out to assess the effect of manure and humic acid application on some elements accumulation and ions concentrations in cotton (Gossypim hirsutum L.) (cotton leaves) under salinity stress. The experiment was conducted as a factorial split plot in the form of a randomized complete block design (RCBD) with four replications in the 2019-2020 cropping year in Beshravieh city in South Khorasan. The main plot included different levels of irrigation water salinity at three levels (2.5, 5.5 and 8.5 ds.m-1) and sub-plots consisted of a factorial combination of manure at two levels (0 and 20 t/h) and humic acid at two levels (0 and 200 gr/ 100 kg of seeds as priming). In order to measure the concentration of sodium (Na) and potassium (K) elements, it was done using a flame photometer and chlorine concentration based on the method provided by Johnson and Ulrich (1995).  In order to assess the cotton yield, the yield of two consecutive harvests were added together and was considered as the seed cotton yield of each experimental unit.

The results of the present study illustrated that the salinity stress increased Na+ and Cl- concentration in cotton leaves and consequently decreased K+ concentration. The increase of salinity stress from 2.5 to 5.5 and 8.5 dSm-1 caused a significant decrease in seed cotton yield. Manure application treatment increased Na+ (13.45%), K+ (2.67%), Cl- (18.30%) concentration in the leaves and seed cotton yield (13/90 %) compared to the no use of manure. Humic acid application treatment decreased Na+ (3.08%), Cl- (9.78%) concentration and increased K+ concentration (4.17%) and cotton yield (9/15 %) and improved the growth conditions compared to the treatment of no use of humic acid. The application of manure (before planting) and humic acid (as priming treatment) increased the seed cotton yield by improving the accumulation of beneficial elements in the leaves under salinity stress conditions.

Based on the results of this experiment, it can be concluded that the application of manure and humic acid (priming) moderated the negative effects of salinity stress on seed cotton yield. In addition, manure and humic acid can be used as an effective and alternative fertilizer in order to reduce the consumption of chemical fertilizers and salinity stress in hot and dry climates. Therefore, manure and humic acid (organic fertilizers) are recommended to be applied under (environmental stresses) salinity stress conditions to mitigate the effects of salt stress and obtain a higher seed cotton yield.

Purple nutsedge (Cyperus rotundus L.) is a problematic weed in tropical regions particularly in Jiroft, Kahnooj and Birjand, so that farmers annually suffer severe damage to their vegetable and cucurbit crops. Currently, very little research on the biological basis of this noxious weed has been don.This study was conducted to evaluate the effect of burial depth on tubes germination and emergence of different purple nutsedge ecotypes. Purple nutsedge tubers were collected from birjand, kahnooj and jiroft regions. A factorial experiment was conducted based on randomized complete block design in University of Birjand with three replications. To investigate the viability of tubers before being used for bioassays, their germination potentials were examined in a growth chamber set at 25/15°C. Then, ten tubers of each ecotype with almost equal weight (3.6gr) and size were planted in polyethylene tubes with 25 cm in diameter and 50 cm in height. Ten tubers of each purple nutsedge ecotype were sown at 8 different depths, including 0, 2.5, 5, 10, 20, 30, 40 and 50 cm. At the termination of experiment, number of tubers and pre tubers, underground tuber dry weight, shoot number and above ground dry weight were recorded. Results showed that purple nutsedge tubers were able to emerge from very deep burial depths (up to a depth of 50 cm), and in this regard, there were some differences among the three ecotypes. Generally, as depth increases, the number and weight of tubers, and shoots decreased; whereas the burial depth showed no effect on the shoot height and pre-tuber production. Therefore, in addition to deep plowing, other control methods such as cultural control and chemical methods should be used in an integrated management.

There is an urgent need to increase per capita food production to compete with high population growth while maintaining environmental sustainability. Because nitrogen plays a vital role in food production for humans and livestock, nitrogen management is essential in food production. In most cropping systems, nitrogen management seems to be a major challenge due to its high mobility and natural tendency for losses from the soil-plant system to the environment. Soil organic carbon plays a key role in improving soil ecological conditions. Adding organic matter to the soil is an excellent tool for improving physical, chemical and biological conditions and is almost always desirable. Soil organic carbon stock of crop ecosystems may be increased by improving farming practices. The application of green manure, fertilizer and the return of crop straw into the soil are known as management operations to increase soil organic carbon. Fertilizers, especially nitrogen, increase crop yield, and organic carbon is returned to the soil through roots and debris, which in most cases leads to increased soil organic carbon.

This study was conducted with the aim of utilizing a set of improving farming practices in diverse cropping systems to improve nitrogen efficiency during two crop years. Farming practices including removal of summer fallow were used by importing three crops of mung bean, corn and wild rocket in rotation plus nitrogen supply levels factor. The crop rotation factor was applied in four levels of Fallow-wheat, mung bean-wheat, corn-wheat and wild rocket-wheat and the factor of nitrogen fertilizer (0, 180 and 360 kg.ha-1) in a randomized complete block design as factorial. Soil mineral nitrogen (nitrate and ammonium) were measured before sowing wheat and grain, straw and total plant nitrogen after harvest. Uptake efficiency, utilization efficiency, agronomic efficiency and nitrogen harvest index were calculated.

The results of combined analysis of variance showed that the crop rotation and nitrogen were significantly effective (ρ ≤ 0.01) on plant nitrogen, harvest index and nitrogen efficiency. Increasing nitrogen fertilizer up to 360 kg.ha-1 increased grain nitrogen, straw nitrogen, total plant nitrogen and also nitrogen harvest index. While the best uptake, utilization and agronomic efficiency of nitrogen was observed on the treatment without nitrogen fertilizer. Comparison of the means showed that the wild rocket-wheat crop rotation had the best result among all measured traits except utilization efficiency, while the utilization efficiency in the corn-wheat crop rotation showed the best performance. The results clearly show the effect of increasing organic carbon on nitrogen availability and grain nitrogen concentration as well as the role of cover crops and legume, in increasing access to nitrogen. The amount of grain nitrogen was directly affected by the amount of nitrogen fertilizer. The highest correlation coefficient was seen between agronomic and uptake efficiency (r = 0.96**). There was also a significant inverse relationship between nitrogen harvest index and the types of calculated efficiencies. The amount of uptake efficiency and agronomic efficiency in all crop rotations except corn-wheat in the second year improved compared to the first year. The highest increase in efficiency in the second year was related to the wild rocket-wheat crop rotation. In the conditions of 360 and 180 kg.ha-1 nitrogen fertilizer, the nitrogen harvest index increased in the second year compared to the first year. While in conditions without nitrogen fertilizer, nitrogen harvest index has a significant decrease. Therefore, at least in the short term, to increase the nitrogen harvest index, the minimum supply of nitrogen fertilizer should be used, even under improving crop management conditions such as green manure, removal of fallow and introduction of legumes in rotation and return of crop residues.

Continuous cropping, removal of fallow, use of cover crops and legume and preservation of residues led to increased carbon and nitrogen sequestration in soil and consequently increase biomass and nitrogen concentration in plant tissue. On the other hand, crop rotations that increased soil organic carbon and improved soil fertility quickly improved nitrogen efficiency and nitrogen harvest index.

To investigate the effects of foliar application of Acadian seaweed extract® and Biomix poultry manure® on qualitative traits and secondary metabolites of saffron, an experiment was conducted as a factorial arrangement based on a randomized complete block design with three replications in the city of Ferdows the during growing season of 2017-2018. Experimental treatments included four levels of Acadian seaweed extract® (0, 1, 1.5, and 2 kg. l000 L-1 water) and four levels of liquid Biomix poultry manure® (0, 2, 4 and 6 L. l000 L-1 water). Measured traits included phenol, anthocyanin, crocin, picrocrocin, safranal, and fresh and dry stigma yield. Results showed the effect of treatments was significant on the studied traits. So that saffron stigma picrocrocin in treatment of 2 kg. l000 L-1 Acadian seaweed extracts® was 26% more than the control. Liquid poultry manure® also had a significant effect on secondary metabolites of saffron, so that saffron stigma picrocrocin in treatment of 6 L. l000 L-1 Biomix poultry manure® was 24% more than the control. Interaction between Acadian seaweed extract® and Biomix poultry manure® had a significant effect on anthocyanin, crocin, safranal, and phenol content. The highest increase was observed in 2 kg. l000 L-1 Acadian® and 6 L. l000 L-1 Biomix poultry manure®. Also, the use of seaweed extract® had a significant effect on stigma yield, so that the yield of fresh stigma (13%) and dry stigma (20%) in the treatment of 2 kg. l000 L-1 seaweed extracts® was higher than the control. According to the results of this study, the use of seaweed Acadian® (2 kg. l000 L-1 water) alone or in combination with Biomix poultry manure® (6 L. l000 L-1water) can play an important role in enhancing the yield and quality characteristics of saffron.

Nitrogen plays an important role in increasing the quantitative and qualitative yield of wheat in dryland regions. To evaluate the effect of nitrogen (urea) by different foliar application treatments and top dressing fertilizer on grain protein and nitrogen remobilization of wheat, a strip split-plot design based on RCBD with three replicates was conducted under dryland and supplemental irrigation conditions during two growing seasons (2016-17 and 2017-18). Experimental treatments were: A: control (without application of N), foliar application of urea during booting, booting + grain filling and grain filling stages as the main plot, B: wheat cultivars as sub-plots, C: top dressing fertilizer including application and non-application (control) in strip factor were considered. The results of combined analysis of variance and mean comparisons showed that foliar application of urea fertilizer in all three growth stages significantly increased grain yield, nitrogen content, percentage and yield of grain protein and grain nitrogen remobilization of shoots. The application of top dressing fertilizer in both dryland and supplementary irrigation conditions was significant on grain protein yield. The highest grain protein yield in both dryland and supplementary irrigation conditions were 393 and 492 kg/ha, respectively. Foliar application at the grain filling stage had the largest role in the nitrogen remobilization to the grain and the control. Foliar application at the grain filling stage had the highest and control (without foliar application) had the lowest share of nitrogen remobilization to the grain.

Nitrogen is a determining element in nutrition, plant growth, and its quantitative and qualitative performance. Considering the high cultivated area of dryland wheat in the country and the economical importance of this crop in dryland conditions, it is necessary to consider any solution to optimize the quantity and quality of this product.

a strip split plot design based on RCBD with three replicates was conducted under rainfed and supplemental irrigation conditions during two cropping seasons (2016-17 and 2017-18) to evaluate the effect of Nitrogen (urea) applied by different foliar application treatments and top dressing fertilizer on grain yield, grain protein content, Zeleny number, and gluten index of wheat, Experimental treatments were: A: control (without application of N), foliar application of urea during booting, booting + grain filling and grain filling stages as the main plot, B: wheat cultivars as sub-plots, C: top dressing fertilizer including application and non-application (control) in strip factor were considered.

The results of a combined analysis of variance and mean comparison showed that foliar spraying of urea fertilizer in all three growth stages significantly increased grain yield, nitrogen content, the percentage of grain protein and grain hardness, Zeleny number and grain gluten index. The application of top dressing fertilizer in both rainfed and supplementary irrigation conditions on grain yield, grain protein and gluten index was also significant. The highest gluten index in rainfed conditions (24.08%) and supplementary irrigation (16.19%) was related to foliar application of urea during the grain filling stage. The highest index of gluten, grain hardness and Zeleny number in both rainfed and supplementary irrigation conditions belonged to Rijaw variety. Rijaw variety had the highest value with 27.3 and Azar-2 variety had the lowest gluten index value with 18.6. Foliar application of urea during the grain filling stage had the most contribution to the increase of grain protein and the control treatment had the least contribution. The highest amount of grain yield in rainfed conditions was 2907 and in supplementary irrigation conditions were 3957 kg, which compared to the control treatment (no application of vinegar fertilizer), increased the grain yield by 19 and 16% in both rainfed and supplementary irrigation conditions, respectively.

The results of this research showed that foliar application treatments and top dressing fertilizer in both rainfed conditions and supplementary irrigation were effective in improving quality traits. In this study, supplementary irrigation led to a significant increase in grain yield compared to rainfed conditions.

Purple nutsedge causes severe damages to vegetable crops in Jiroft, Kahnooj and Birjand. In order to evaluate the effects of high temperature and time of exposure to high temperatures on various ecotypes of purple nutsedge tubers, a factorial experiment was conducted based on randomized complete block design with 3 replications in the Research greenhouse of Birjand University, Iran, in 2016. Experimental factors consisted of 3 ecotypes (Jiroft, Kahnooj and Birjand), different temperatures from 40 to 60°C with 5°C increments, and exposure time including 1, 2, 4, 8, 16, 32 and 64 hours. Results indicated that at all exposure times, 40°C temperature did not affect the growth characteristics of purple nutsedge, while at 45 °C, increasing the exposure time decreased the growth characteristics of purple nutsedge. Three-parameter logistic model estimation showed that  tuber viability (T50) at 45 °C in Jiroft ecotype was 14.64 hours, it decreased to 5.01 hours  at 50 °C. T50 was about 66% lower than for 45 ° C, but it was 19.76 hours in Kahnooj ecotype at 45 °C, while at 50 °C, this parameter decreased to 2.73 hours (86.2%). T50 of Birjand ecotype at 45 °C was 12.90 hours, but at 50 °C, the tubers viability reduced and T50 was 8.91 hours (31% decrease). Results of this research could have an important role in controlling purple nutsedge in vegetable fields.

To evaluate the additive effect of intercropping of potato and quinoa, and weed management on yield and quantitive traits of potato, this study was conducted in a split plot experiment based on randomized complete block design (RCBD) with four replications at Jiroft and Kahnooj regions. Weed management treatments (control, without controlling weeds), paraquat herbicide (3 liter per hectare) and manual weeding, were considered as the main plot, and additive intercropping patterns (potato: quinoa in density levels of 5:15, 5:20 and 5:30 plants.m-2) and potato sole cropping (5 plants.m-2) were assigned to sub-plots. Based on the results, intercropping cultivation had significant effects on reducing weed densities and increasing plant height, leaves number per plant, leaf area index, tuber number per plant, tuber yield and marketable tuber yield. Increased densities of quinoa in intercropping cultivation caused an enhancing trend in potato plant height (4.2-9.1 %), leaves number per plant (7.9-16.6 %) and leaf area index (5.6-12.7 %) as compared to potato sole cropping treatment (control). Manual weeding, also decreased in weed density (16.1 %), and increased leaves number per plant (3.7 %), tuber number per plant (9.4 %), tuber yield (6.3 %) and marketable tuber yield (9.8 %) in comparison to that of paraquat herbicide treatment. The highest mean tuber number (7.5 number.plant-1) was observed in the 5:20 intercroping treatment, which resulted in 7.1% increase in the tuber number as compared with the control treatment. Highest tuber yield (4.54 kg.m-2) and marketable tuber yield (4.01 kg.m-2) were also obtained with the 5:20 intercroping treatment under manual weeding at Kahnooj region, and resulted in 69.4 and 20 % increases in tuber yield and marketable tuber yield respectively, as compared with the potato sole cropping without weeding (control treatment) in this region. Generaly, the best results were obtained in potato and quinoa intercropping with density of 5:20 plants.m-2 under manual weeding at Kahnooj region

Intercropping system is the growth of two or more crops at the same time, which can lead to decreases in the risk of total crop reduction and increases in yield with control of weeds. Quinoa (Chenopodium quinoa willd.) is a pseudo cereal with high nutritional value which is approximately a new crop in Iran. So, this research was conducted to assess the effects of additive intercropping of quinoa andpotato (Solanum tubersum L.), and the methods of weeds control on yield and yield components of quinoa var. Titicaca in Jiroft and Kahnooj regions.

This study was carried out as split plot based on a randomized complete block design (RCBD) with four replications at Jiroft and Kahnooj regions. Therefore, weeds control treatments including control (no-hoeing), manual weeding (twice within 30 days after planting) and paraquat herbicide (3 days after planting of quinoa) were arranged in the main plots, while additive intercropping patterns at five levels (Q:P in the levels of 5:5, 10:5, 15:5, 20:5 and 30:5 plants per m-2), quinoa sole cropping (30 plants per m-2) and potato sole cropping (5 plants per m-2) were located in sub-plots. The effects of quinoa and potato intercropping on plant height, leaves number per plant, leaf area, flowering time, spike maturity and quinoa harvest time, average of grain weight per plant, grain yield and density of weeds as well as potato tuber yield were measured at both regions. Data were analyzed as combined analysis of variance (ANOVA) using SAS ver. 9.2. Means were compared using the least significant difference (LSD) at the 5% level (P = 0.05).

The results showed that the effects of quinoa and potato intercropping had significant effects on some characteristics of quinoa including leaves number per plant, leaf area, average of grain weight per plant, grain yield of quinoa, tuber yield of potato and density of weeds. However, intercropping had no effect on some characteristics of quinoa such as plant height, flowering time, spike maturity and quinoa harvest time. Based on the results the highest (19 g per plant) and lowest (13.9 g per plant) average of grain weight per plant were obtained in 20:5 and 5:5 plants per m-2 treatments, respectively. Whereas, the highest grain yield (4957 and 4863 kg.ha-1) were obtained in sole quinoa and 30:5 plants per m-2 treatments, respectively. The studied growth characteristics and grain rate per plant in Kahnooj were greater than those in Jiroft. Total land equivalent ratio (LER) index increased with increasing quinoa density in intercropping. The highest total LER was obtained in 30:5 plants per m-2 treatment in Kahnooj region. Moreover, the effect of manual weeding of weeds on the studied properties were more than that of the application of paraquat herbicide. The results also showed that the intercropping of quinoa and potato led to decreases in density of weeds at both flowering and before harvesting times. So that, the lowest density of weeds was related to the intercropping of quinoa and potato with densities of 20:5 and 30:5 plants per m-2 treatments. Whereas the highest rate of density of weeds were related to the sole cropping of quinoa and potato treatments, respectively. Moreover, the results showed that intercropping resulted in greater tuber yield of potato, so that the highest potato tuber yield was obtained in 30:5 treatments.

Based on the results, although the highest average grains per plantwas obtained in the intercropping of 20:5 treatment, the yield of quinoa decreased with the intercropping of quinoa and potato compared with the quinoa sole cropping. Also, the additive intercropping led to decrease in the density of weeds. Although, it seems that for quinoa cropping the climate of Kahnooj is more suitable than Jiroft, the intercropping of potato and quinoa is suitable for Kahnooj and Jiroft regions.

Plants in arid and semi-arid regions are constantly exposed to environmental stresses such as salinity. The sensitivity of different plants to salinity stress at different growth stages is quite different. In many plants, perhaps the most sensitive stage of the plant growth cycle to salinity, is germination and emergence stages. Germination and emergence of seeds are the first important stages in plant establishment which is affected by most environmental stresses. In South Khorasan, which has saline soil and water, conventional millet cultivation is common, and it’s most important weeds are lambsquarters, tumble pigweed and purslane. Since the irrigation of millet fields in this region of the country is performed with saline water, this experiment was conducted out to investigate the emergence response of millet and lambsquarters, tumble pigweed and purslane weeds, under sodium chloride salinity in Hoagland solution.

In order to evaluate the effect of salinity stress on quality and emergence rate of common millet, lambsquarters, tumble pigweed and purslane, four separate experiments were conducted out in a randomized complete block design with three replications in 2017 in the research greenhouse of agricultural faculty at Birjand University. Experimental treatments consisted of 10 salinity levels including Hoagland solution with 2 dS/m as control, 4, 6, 8, 10, 12, 14, 16, 18 and 20 dS/m (created sodium chloride in Hoagland solution). Hoagland formula was used for preparation of nutrient solution and sodium chloride was used for preparation of different salinity levels. After filling each pot with 1.5 liters of acid washed sand, 25 seeds from each species were placed at 1 cm depth from soil surface. Seedling emergence were counted daily. In order to investigate the response of each species to salinity stress, the emergence percentage in each species was analyzed in a randomized complete block design without considering treatments with zero emergence percentage. Data analysis was performed using SAS software. GLM procedure was used for analysis of variance and comparison of mean performed with protected LSD at 5% probability level.

The results showed that common millet, purslane, tumble pigweed and lambsquarters seeds had the ability to germinate up to 20, 16, 12 and 12 dS/m, respectively. The start of emergence for common millet seeds up to 10 dS/m and tumble pigweed up to 8 dS/m was 3 days after sowing. Meanwhile, the seeds of lambsquarters emergence up to 6 dS/m on the fourth day, and purslane in 2 dS/m on the second day after sowing. Millet plants were emergence up to 18 dS/m salinity in the first five days after sowing. The results also showed that for common millet and tumble pigweed, no significant difference were observed for single seedling dry weight at 2 and 4 dS/m. Increasing salinity from 2 to 4 dS/m led to a significant decrease in purslane seedling dry weight but with increasing salinity stress from 4 to 8 dS/m, the reduction in seedling dry weight was not significant. In this study, with increasing salinity stress from 2 to 8 dS/m, dry weight of common millet, purslane, lambsquarter and tumble pigweed decreased by 55, 73.8, 80.7 and 79.5%, respectively. In this study, after ensuring that the seeds did not emerge, to determine the viability of non-emerged seeds, the pots were irrigated with distilled water. Under this condition, non-emerged millet seeds in the pots were not able to germinate at any levels of salinity stress. Purslane had no germination under salinity stress of 18 and 20 dS/m, but there were 34% and 62% emergence percentage respectively, when the salinity were terminated. Under mild stress, the percentage of germinated purslane seeds was 18% after recovery, which decreased with increasing salinity up to 12 dS/m and then increased.

In general, the results showed that salinity stress caused a change in the emergence behavior of millet and purslane, tumble pigweed and lambsquarters weeds. Common millet had the ability to germinate at all levels of salinity stress, but tumble pigweed and lambsquarters had the potential to emerge up to 12 dS/m and for the purslane up to 16 dS/m. Also, with increasing salinity stress from 8 to 16 dS/m, dry weight of seedling of common millet, purslane, tumble pigweed and lambsquarters decreased by 66, 82, 100 and 100 percent, respectively. At the end, the results showed that occurrence of salinity stress and its removal, the purslane seeds had a greater ability to keep their viability, whereas the common millet seeds completely lost their viability.

Cumin (Cuminum cyminum L.) is one of the most important domestic medicinal plants in the country. Currently Iran is one of the most important producers of cumin. Features such as short growing season, low water requirement, lack of interference with other crops, high economic justification for other crops and exportability, make this plant a special place in the pattern of cultivated area This plant has a special place in the cultivation pattern of arid and semi-arid regions, including Khorasan. Given that cumin is a delicate plant with low weed competitiveness and on the other hand because it leaves cover the ground as much as possible, it provides a suitable environment for weed growth and development. Although cumin growers are currently struggling with weeding the fields mechanically, this method is costly and damages to the cushion bushes, identifying the herbicide of choice for combating weeds. The weeds of this plant will be a great step towards reducing the cost of its production. Therefore, the purpose of this study was to evaluate the chemical control of weeds and to evaluate the cumin tolerance to herbicides and to select herbicides for this important medicinal plant.

In order to evaluate the efficacy of herbicides from cell division inhibitor and photosystem II inhibitor groups, an experiment was conducted as a randomized complete block design with 6 treatments and 3 replications in Agricultural Research Farm at University of Birjand 2017. In this research herbicides from cell division inhibitors group including trifluralin pre-plant incorporated (2 L.ha-1), pendimethalin pre-plant incorporated (3 L.ha-1), pendimethalin preemergence (3 L.ha-1) as well as herbicides from photosystem II inhibitors group including prometryn preemergence (2 Kg.h-1), metribuzin preemergence (1 Kg.h-1) and a weeding treatment was also added. The measured traits for weeds included: height, density, dry weight, leaf area and for cumin included: seed yield and biological yield.

According to the results of analysis of variance, herbicide treatments had a significant effect on density, height, dry weight and leaf area at different stages of weed sampling. Comparison of mean data on total weed density showed that after weeding treatment, application of pendimethalin preemergence caused an almost 100% reduction in total weed density, which was not statistically significantly different from pre-plant incorporated trifluralin. Concerning weed height, the results showed a significant decrease in the effect of herbicides on weed height. Comparison of means showed that preemergence and pre-plant pendimethalin had a great impact on weed leaf area reduction. Experimental treatments had a significant effect on weed dry weight. Results showed that pendimethalin herbicide had the greatest percentage of reduction in total weed dry weight after weeding treatment. The results of visual assessment also indicated the greater impact of cell division inhibitor herbicides on weed control at all three sampling stages. Preemergence pendimethalin had the greatest efficiency in weed control, whereas metribuzin and prometryn had the least efficiency in this regard. Moreover, the results of visual assessment of herbicide effects on cumin showed that pendimaline had no significant effects on cumin either in pre-plant or pre-emergence applications, probably due to the rapid metabolism of this herbicide in the plant and its low mobility in the soil. The greatest damage to cumin was related to metribuzin. The results showed that the greatest seed yield was related to full-season weeding treatment, followed by pendimethalin herbicide application which caused a 204% increase in the crop seed yield and the lowest seed yield was related to metribuzin with 63% reduction in crop seed yield. It seems that due to relatively long survival of metribuzin in the soil (30-60 days) and the high susceptibility of cumin to this herbicide, it caused severe damage to the crop.

All herbicides applied in this study showed an acceptable level of control over weeds in terms of percentage of density reduction, dry weight, height, and leaf area of ​​weeds. Pendimethalin herbicide after weeding all season had the highest percentage of grain yield and biological yield enhancement, while the least performance was related to metribuzin. According to the results of the visual assessment, the greatest and least impacts of herbicides on weeds was occurred with pendimethalin and metribuzin, respectively. In general, according to the results of this study, pendimethalin herbicide can be effective in controlling weeds and enhancing the yield of cumin because of its greater inhibitory effect on weeds as well as its safety for cumin.

Sufficient nutrition on crop is one of the most important factors for improving wheat grain yield and quality. To evaluate the effect of Nitrogen (urea) by different foliar application treatments and top dressing fertilizer on yield and yield components of wheat, a strip split plot design based on RCBD with three replicates was conducted under rainfed and supplemental irrigation conditions during two cropping seasons 2016-17 and 2017-18. Experimental treatments were: A: control (without application of N), foliar application of urea during booting, booting + grain filling and grain filling stages in main plot, B: different wheat cultivars including in sub plots, C: top dressing fertilizer including application and non-application (control) in strip factor were considered. Based on combined-ANOVA, the effect of year under rainfed condition was significant for grain yield, biological yield, number of grain per spike, number of spike/m2, harvest index and spike length. Application of N as top dressing fertilizer had significant effect on all studied traits in both rainfed and supplemental irrigation conditions. Also, foliar application of N in the all three stages increased BY, GY, 1000-grain weight, NGPS and SL. In terms of GY under rainfed conditions, Paraw cultivar had the most grain yield and yield components with the highest biological yield. Under supplemental irrigation condition, Baran cultivar had the highest grain yield, while Azar-2 produced the lowest gain yield in both rainfed and supplemental irrigation conditions.

The aim of this study is to investigate the effect of foliar application of Acadian seaweed extract and Biomix liquid poultry manure on vegetative growth, corm, and yield of saffron. The experiment was conducted in a randomized complete block design with three replications in the city of Ferdows city during the 2017-2018 growing year. Experimental treatments included four levels of Acadian seaweed extract (0, 1, 1.5, and 2 kg. l000 L-1 water) and four levels of liquid Biomix liquid poultry manure (0, 4, 5, and 6 L. l000 L-1 water). The results showed a significant effect of treatments on the studied traits, such as maximum number of flowers (99.50 N. m-2), fresh yield of flowers (33.34 g.m-2), dry weight of saffron stigma (0.341 g. m-2), dry leaf weight (0.592 g plant-1), and leaf length (63.75 cm) obtained in 2 kg. l000 L-1 seaweed extract. Besides, the results showed a significant effect of liquid poultry manure on flower number and yield (94.250 N.m-2 and 32.285 g. m-2, respectively), leaf length (60.66 cm), fresh and dry leaf weight (0.74 and 0.46 g.m-2, respectively), and total weight of replacement corm (37.02 g.m-2). Also, the least amount of the mentioned traits were observed from the control treatment. The interaction between these two fertilizers was also significant in fresh and dry leaf weight and the total and average diameter of replacement corm. Thus, fresh and dry leaf weight (210% and 273%, respectively) were highest in the treatment of 2 kg. l000 L-1 of seaweed extract and 6 L. l000 L-1 of liquid poultry manure. Moreover, total and average diameter of replacement corm (33% and 50%, respectively) were highest in the treatment of 2 kg. l000 L-1 of seaweed extract and no liquid poultry manure. According to the results of this study, the use of Acadian seaweed extract (2 kg. l000L-1 water) alone or in combination with Biomix liquid poultry manure (6 L. l000 L-1 water) can play an important role in enhancing the vegetative growth, corm, and yield of saffron.

Avoidance of repeated soil tillage in conjunction with maintaining crop residues and plant nutrition management may help to conserve and improve the soil and plant conditions. Primary goals of conservational systems consist of eliminating some cultivation practices and increasing surface crop residues in the planting system. In such residue conserving systems, nitrogen fertilizers are considered as important elements in crop production and influence the pattern of soil organic carbon storage as well as crop growth and yield. Currently, cotton is mainly cultivating in many farms of the country, and in particular in the Southern Khorasan province, after removal of the residues of the previous crop, and few studies have been conducted on the importance of plant residues in this plant in Iran. Therefore, this research was carried out with the aim of investigating the interaction of barley plant residues and different levels of nitrogen on yield and yield components of cotton in two different tillage systems (conventional tillage with moldboard plowing and reduced tillage with disk).

To study the effect of application of different residue amounts and nitrogen fertilizer under two different cultivation systems on dry matter accumulation, yield and yield components of cotton, an experiment was conducted as split-plot factorial design with three replications at the Faculty of Agriculture, University of Birjand, Birjand, Iran. The main plot consisted of two cultivation levels including conventional tillage (mould board plowing) and reduced tillage (disking). The sub-plot included two nitrogen levels (50 and 150 kg.ha-1) and five levels of barley residues (0, 77, 154, 231 and 301 g.m-2) which were factorial arranged in sub plots. Cotton, Khordad cultivar, was planted on 20th June 2013. Plant dry weight was measured at three stages over the growing season and cotton bolls were collected at two stages and the lint, seed cotton and cottonseed yields was recorded.

Results showed that the cotton emergence in moldboard plowing (46.8%) was significantly higher than disk (38.1%), and seedling emergence in both tillage systems decreased with increasing amount of residues on the soil surface. The highest percentage of emergence was related to zero residues in moldboard plowing and the lowest emergence was observed in low tillage (disc) with residues of 308 g.m-2. The residue application also reduced the plant dry weight early in the growing period. Although application of low amounts of residues reduced plant dry weight and cotton seed and lint yields compared to non-residue application at the end of the growing season, increased levels of residues, especially where high rates of nitrogen application and moldboard plow were practiced, remarkably increased these traits, so that the greatest lint yield (1.04 ton.ha-1) was observed with 308 g.ha-1 of residue in conjunction with application of 150 kg.ha-1 nitrogen and practicing moldboard plowing. Moldboard plow system caused a greater dry matter accumulation and crop yield and it seems that initiation of crop residue conservation and reduced tillage requires more time.
 
 

The research clearly demonstrated the beneficial effects of not removing plant residues and mixing them with soil even for a single crop season, which, in turn, emphasizes the avoidance of incorrect burning of the residues of the previous crop. According to this study findings, where 100% of previous crop residues are added to the soil, the application of nitrogen should be increased proportionally. Otherwise, a significant reduction in crop yield and yield components would be observed especially at high rates of crop residues. Moreover, it appears that reduced cultivation systems might not influence crop yield and even reduce it in short term and requires long term research studies to determine the efficacy of conservational cultivation systems.

Light is a vital component for photosynthesis and plays a significant role in the competitive ability of plants. The nitrogen response of competing plants may be affected by radiation availability and maximum potential growth rate, which determine plant N requirements. Shading reduces the light intensity, which leads to changes in the morphology, physiology, biomass, grain yield, and quality of crops. Moreover, shading stress delays flowering and decreases biomass and grain yield. Since photosynthesis results in dry matter accumulation, and reduced light is known to limit carbon accumulation and nitrogen content, understanding these processes in weeds may provide insight as to their effects on crop production, help to predict their occurrence, and ultimately provide the needed information for their management. In order to evaluate foxtail millet competition with pigweed at different levels of radiation and nitrogen, two separate experiments were conducted in split plot arranged in randomized complete block design with three replications at the Research Farm of Birjand University in 2015. Texturally the soil was loam, with 8.16 pH, 0.03% total N, 12 ppm available P and 250 ppm available K. The experiment was laid out in a split-plot design with three replications having three shade levels (0, 41 and 75% shade) in main plot and three pigweed density (0, 12 and 24 plant per square meter) in subplots in two separate experiments, one under nitrogen application and the other without nitrogen usage. In 0% shade treatment, sunlight was allowed to fall over the millet and pigweed without any barrier. In 41% and 75% treatments, however, the light levels in the form of PAR were reduced using shade nets. At the end of growth stage millet traits including days to panicule emergence, days to maturity, grain filling period, number of grain per panicule, 1000 grain weight, grain yield, forage yield, biomass and harvest index were measured. Data analyses were performed using two-way analysis of variance (ANOVA) with SAS 9.1. Means of treatments were compared between nitrogen, shade treatments and pigweed densities according to protected least significance difference (FLSD) test at the 5% level. Nitrogen had a significant effect (P < 0.01) on days to panicule emergence, days to maturity at 1% probability level and on grain filling period and grain yield at 5% probability level. Application of 150 kg nitrogen per hectare led to improvement of phenological traits and grain yield of millet. Nitrogen can extend vegetative growth stage period of plants and reduce grain filling rate (Nezamzadeh et al., 2011). Also, nitrogen fertilizer can increase grain formation and grain yield through improvement of photosynthesis ability owing to increases in leaf area index and leaf area duration (Moosavi et al., 2015). Shading had a significant (P < 0.01) influence on millet phenological traits and grain yield and had a significant effect (P < 0.05) on number of grain per panicule. Shading at level of 75% dramatically reduced number of grain per panicule and grain yield of millet while increased days to panicule emergence, days to maturity and grain filling period. Nasrollah-zadeh et al., (2011) also reported that grain filling period of faba bean increased by 3-4 days in shaded plants in comparison with control. With shading stress at its highest level, grain yield was significantly reduced by 61% from 3.70 to 1.44 ton per hectare. The effect of pigweed density on grain yield (P < 0.05) and plant height and stem diameter was significant (P < 0.01). The effect of pigweed density was also significant on forage yield (P < 0.01) and days to panicule emergence and grain yield (P < 0.05). Pigweed density of 24 plants per square meter led to 21% reduction in millet grain yield against control. The interaction between nitrogen and pigweed density on millet traits was limited, and only significantly (P < 0.05) affected grain yield. In competition of crops and weeds, the space required for crop to expand the leaf area decreases, and the competition between the species increases to absorb the active photosynthesis radiation. Under these conditions, less assimilates are transmitted to the reproductive organs, which has a profound effect on reduction in grain yield and further on harvest index (Gholamhoseini et al. 2015). The results of this study showed that the grain yield of foxtail millet reduced by 61 percent with increasing of shading intensity contrasting with no shading. This reduction was due to the negative effects of shading on the number of grain per panicule and 1000-grain weight. Harvest index also decreased with increasing shading levels. The reduction in harvest index was due to a greater reduction in grain yield contrasting dry matter production at shading treatments. Also, grain yield at the highest level of pigweed density was 21% lower. These results, considering the importance of weed control, show that proper management of weed control in the field by providing conditions to faster closing canopy in order to reduce the competition of pigweed can be effective in grain yield improvement of foxtail millet.

Introduction Potato is amongst the most important crops in the world, which is the third most consumed crop worldwide after rice and wheat and is followed by corn in this regard (Kazemi et al., 2016). Abiotic stresses like drought may cause adverse effects on growth and tuber yield of potato plants as they are very sensitive to soil moisture reduction (Deblond et al., 1999). Potassium is used as a cofactor of enzymes, osmotic activities and plant electrolyte regulation, and is an essential element for osmotic control that can reduce osmotic potential and improve plant acclimatization under drought conditions (Taiz & Zeiger, 1991). Given the importance of potato production and its high demand for water and because of scant research being conducted on the planting patterns of this crop, the present study aimed to investigate the effects of various planting patterns and different potassium levels on potato growth indices under water-limited conditions in Khorasan Razavi province. Materials and Methods This experiment was conducted in Jolge Rokh- agricultural research station over spring and summer of 2016 and 2017 cropping seasons. The experiment was set up as split split plot arrangement based on a randomized complete block design with three replications. The trial factors consisted of three planting patterns including common planting, common dense planting and zigzag planting designated as the main plots, and irrigation with three levels [control (without stress), irrigation based on 80% of the crop water requirement (as deficit irrigation treatment), and irrigation based on 60% of the crop water requirement (as stress treatment)] designated as the sub -plots, and three levels of potassium fertilizer (0 (control), 75 and 150 kg potassium sulfate per hectare) designated as sub-subplots The water needed for the plant was determined based on water requirement of the potato, which was determined using the software (OPTIWAT) and FAO Penman- Monteith method. The leaf area and leaf dry weight were measured during the growing period at two-week intervals. Results and Discussion The results showed that the greatest leaf area index (LAI), crop growth rate (CGR) and total dry matter (TDM) were observed with zigzag planting pattern at either year of the study. The maximum TDM under common, common dense and zigzag planting in the first year were 634.3, 671.9 and 870 g.m-2, respectively, while the corresponding values for the second year were 808.5, 919.2 and 1065 g.m-2, respectively. Irrigation treatments based on 80 % and 60% of the crop water requirement reduced the growth indices and yield of the tubers. The greatest tuber yield was observed with full irrigation treatment (100% of the crop water requirement (32 and 35.2 ton. ha-1 in the first and second year, respectively), while the lowest tuber yield was obtained with 60% of the crop water requirement (20.2 and 20.4 ton. ha-1 in the first and second year, respectively). The results showed that potassium sulfate increased TDM, LAI, CGR, NAR and tuber yield. The application of 150 kg of potassium sulfate produced the greatest TDM (850.2 and 1118.9 g.m-2 in the first and second year, respectively), whereas no fertilizer usage gave the lowest TDM (584.2 and 743 g.m-2 in the first and second year, respectively). In potato plants, sufficient quantities of potassium increase the number of tubers and dry matter production through strengthening potato stems, and at the same time, the plant can acclimatize to environmental stresses. Conclusion The results showed that the greatest LAI, TDM, CGR, NAR and tuber yield were observed with the zigzag planting. On the other hand, irrigation based on 60% the crop water requirement reduced the growth indices and tuber yield. It is worth noting that applying 80% of the crop water requirement also decreased the investigated the growth traits of the potato plants. Therefore, it is recommended that the exposure of potato plants to deficit irrigation conditions be avoided and the efforts should be made to provide them with adequate water. But the remarkable point was that the usage of potassium sulfate fertilizer could enhance and improve growth rates under low irrigation and water stress conditions.

The cultivation of crops in most parts of the world, in addition to competing with different weed species, is affected by a variety of environmental stresses, including salinity stress. The changes in the growth rate and production of crops under the influence of salinity stress and competition with weeds have been extensively studied. However, what is currently less investigated is the competition of several species of weeds with crops and the competition of crops with weeds under salt stress. Therefore, the aim of this experiment was to evaluate the competition between tumble pigweed, common purslaneand and common millet under soil salinity stress. This study was conducted as a factorial experiment based on a randomized complete block design with three replications. Experimental treatments consisted of two rates of soil salinity (3 and 10 dS.m-1), and different ratios of interference of the three species (tumble pigweed, common purslaneand, millet) including 0-0 -100, 0-25-75, 12.5-12.5-75, and 25-0-75, 50-0-50, 25-25-50, 0-50-50, 75-0-25, 37.5-37.5-25, 0-75-25, 0-100-0, 50-50-0 and 0-100-0. The desired density in each pot was constant and equal to 8 plants. After preparing the soil and passing through a 2 mm sieve, fertilizer and saline solutions were added to the soil and the soil was transferred to 5 kg pots. Then all three plants were planted and attained to intended density at the four leaf stage. At the end of the experiment, each plant species was separately harvested from each pot and were weighed after complete drying. Finally, for analyzing the results of the experiment, relative yield indicators, total relative yield (Land Equal Ratio), relative crowding and agressivity indices were used. The results showed that increasing soil salinity decreased the dry matter produced by common millet, tumble pigweed and common purslane by 19.5, 4.7 and 27.8 percent, respectively. Comapring the relative yield of millet with those of tumble pigweed and common purslane and also both weeds together by different ratios of planting showed that these values were more than predicted ones under either 3 or 10 dS.m-1 salinity level, which indicates the weak competitive ability of these two weeds against millet. The results of the relative crowding index of species showed that in the ratio of 75% of millet and 12.5% tumble pigweed and 12.5% of common purslane, the greatest rate of relative crowding index was achieved for millet under salinity level of 3 dS.m-1. Also, the greatest relative crowding index of tumble pigweed and common purslane under either salinity level was observed with the cultivated ratio of 75% for both weeds and 25% for millet, suggesting an increased competitive ability of these two weed species through increasing their density even under a higher level of soil salinity. By evaluating the agressivity index between tumble pigweed and purselane, it was found that this value was negative for purselane under the salinity level of 3 dS.m-1. Therefore, it seems that tumble pigweed is more competitive than the common purslane where both weed species grow together. In general, the results of this study showed that in conditions of salinity of 3 and 10 dS.m-1, common millet had more competitive ability than the two studied weeds, but with increasing salinity level, competitive ability of millet was reduced, while it increased weeds competitiveness. Therefore, in the situation of high weed densities, we may expect a greater damage to crops under salinity stress.

Conservation agriculture is an appropriate strategy for maintaining and improving agricultural resources which increases crop production and stability and also provides environmental protection. This attitude contributes to the conservation of natural resources (soil, water, and air) and it is one of the most effective ways to overcome the drought crisis, water management and compensation of soil organic matter in arid and semi-arid regions. Practicing the conservation agricultural systems, which requires an effective usage of previous crop residues and reduced tillage methods, is an irrefutable necessity for arid regions like South Khorasan with low soil organic matter. The addition of crop residues to the soil in conservation agricultural systems, however, might immobilize nitrogen as an important nutritional element affecting plant growth. The transition from traditional to conservation agricultural systems, nevertheless, would affect different constituents of agroecosystems including weeds dynamics and growth, which would eventually affect the crop production in these systems. Given that South Khorasan farmers still use traditional methods of cultivation and they do not return the previous crop residues to the soil in their farming systems, the aim of this study was to investigate the effect of crop residue management and nitrogen on dynamics and growth of weeds of cotton farm. In order to investigate the effect of crop residue management and nitrogen on the growth and dynamics of weeds of cotton farm, an experiment was carried out as split factorial design based on RCBD with three replications at the research field of Faculty of Agriculture, University of Birjand in 2013. In this experiment, the main plot was two tillage methods, including conventional tillage (moldboard plowing) and reduced tillage (disking) and the subplot consisted of a factorial combination of two nitrogen levels (50 and 150 kg ha-1) and five barley residue levels (0, 77, 154, 231 and 308 g m-2) which have been randomly distributed as a factorial in subplots. Weed samplings were performed at four stages including 30, 60, 90 days after planting and also at harvest time and after each sampling, weed density, dry matter and leaf area were measured. Results showed that plow type, residual amount levels and nitrogen fertilizer rate had significant effects on measured traits of weed species including density and dry matter of weeds as well as their leaf area. Increasing the residue amount significantly reduced weeds growth traits. The greatest density, dry matter and leaf area of weeds were observed with disk plow, while mouldboard plowing significantly reduced these traits. A lower disturbance of soil in conservation agricultural systems, which is the case with our study where disking was applied, often results in most weed seeds to accumulate on the upper soil layers and eventually might ends up with a higher weed density. The greater rate of nitrogen resulted in higher density, dry matter and leaf area of weeds. The stimulatory influence of nitrogen on weed emergence has been previously substantiated. Moreover, the interaction effects of studied factors were significant on weeds growth traits. The interaction effects of plow type by residue amount showed that the lowest weed densities were observed with mouldboard plow under all residue amount and the using greatest residue amount (308 g m-2) resulted in the lowest weed density under both tillage regimes. The control treatment (no residue) interestingly showed a lower amount of weed density compared with residue amounts of 77 and 154 g m-2. Weed control by crop residues is probably due to different factors like prevention of light penetration to the soil surface, exuding allelopathic substances, influencing soil nitrate content and moderating soil temperatures and improving crop growth. Our study, however, showed that lower amounts of residues on the soil surface cannot provide enough inhibitory effects to suppress weeds and might even stimulate weed emergence through maintaining more moisture under the residue layer at hot air of early summer. The results of this study revealed that although employment of conservation tillage systems is a suitable method to achieve sustainable agriculture, more extensive research studies are needed on the effects of these systems on weed density and their competition with crop plants. Thus, cover crops and conservation tillage systems can be used as a promising solution for the development of sustainable agriculture and protecting the health of ecosystems. Due to widespread cultivations of wheat and barley in our country, it seems that incorporating the cereal crop residues into the soil might inhibit weeds growth in cropping systems. Our study also showed that nitrogen management is very important strategy in regard to weeds growth in these systems.

Drought and water shortage are the most important limiting factors in agricultural production, and environmental stresses are considered as the most serious threats for seed germination and crop growth. Researchers have mentioned crop residue management as one of the methods to improve soil physical properties, reduce evaporation intensity and protect the environment against global warming. Crop residue also contains a lot of organic matter which has a high water holding capacity, thus the addition of plant residue to soil could result in an effective increase in soil water holding capacity. With regard to importance of soil and water conservation, proper crop residue management plays important role in crop production in arid and semi-arid regions. According to a special role of crop residue in maintaining soil moisture and increasingly spreading of drought stress in the country, this research examines the impact of crops residues and on the emergence and early growth of safflower and wheat crops under different moisture levels.
To study the effect of different levels of moisture and the type of crop residues on germination and early growth of safflower and wheat crops, separate experiments for each plant were conducted in the greenhouse of Faculty of Agriculture, University of Birjand. For this purpose, a factorial experiment for each crop was conducted in a CRD with three replications that contained three levels of moisture (25, 50 and 80% of water holding capacity of the pot) and 5 types of crop residues (chickling pea, rocket salad, triticale, barley and control (no residue on the surface of the pot)). During the trial, number of emerged seedlings was recorded and cumulative rate of seedling emergence was calculated. At the end of the study, the seedlings height was measured and plant from surface of the soil were harvested. After measuring the leaf area of plants, their dry weight were measured.
Result and Results showed that the final percentage of seedling emergence and height of wheat at moisture levels of 50 and 80% of field capacity were not significantly different while these traits significantly decreased in moisture level of 25% field capacity. Wheat plant height was significantly increased just with residues of chickling pea compared to control. Results of interaction effect showed that in general, in moisture levels of 50 and 80% of field capacity, the cumulative rate of seedling emergence of wheat in different treatments of crops residues had no significant difference with the control. However, at 25% of field capacity, cumulative rate of seedling emergence of wheat was greater than the control at all levels of cover crops residues. This result suggests that under low moisture levels, the presence of residue of cover crops on the soil surface can improve emergence rate, probably due to more moisture maintenance in the soil surface by residue of cover crops.
Results for safflower showed that cumulative rate and final percentage of emergence of safflower in all types of crops residues decreased compared to the control. It seems that plant residues have inhibitory effect on safflower emergence. Previous reports have also confirmed that when the crop residue are on the soil surface, emergence of some plants, especially broad-leaved species like safflower, delay, because of the physical barrier that prevents the growth of seedling plumule to the soil surface, while narrow-leaved plants easily pass through plant residues and plant residues do not prevent their emergence.
Moreover, in the treatment of 80% of field capacity, the dry weight of safflower in crop residue treatments of chickling pea, rocket sativa, and triticale increased compared to the control and the greatest dry weight of safflower was observed with the chickling pea residues. In the treatment of 50% of field capacity, dry weight of safflower in all treatments of crops residues were greater than the control and in the treatment of 25% of field capacity, dry weight of safflower were greater in chickling pea and rocket sativa residues compared to the control. Crop residues increase soil moisture content through enhancing the soil organic carbon, as well as reducing run off and evaporation in surface soil. More water content and reduced evaporation caused by the residue mulch are the main reasons for the increase of germination, emergence and seedling growth. (Malhi et al., 2006).
The results showed that the crop residue had a positive impact on the growth of the safflower and wheat under drought stress. Crop residue of chickling pea, especially under stress conditions had a positive impact on growth characteristics of safflower and wheat. Therefore, the use of crop residue can be a useful way to increase the usable moisture in arid and semi-arid regions.

Considering the importance of potato in supplying the country's required food and its dependent industries and also the climatic situation of most regions of Iran as arid and semi-arid, studying the effect of water deficit stress on potatoes is very valuable. Since one of the suitable areas for cultivating potatoes in Iran is Khorasan province, comprehensive studies on this plant cultivation including planting arrangement and effects of water deficit on the plant, seems necessary. So, the purpose of this study was to evaluate the effects of different levels of moisture on potatoes in different planting patterns and also the possibility of potassium application for reducing the impacts of water deficit.
In order to study the effects of different levels of moisture on potato under different cultivation systems, an experiment was conducted in the field on the plain of Rokh in Khorasan Razavi, Iran over 2016 cropping season. This research was set as split- spilt plot in randomized complete block design with three replications. Trial factors consisted of planting pattern at three levels (normal planting, usually dense planting and zigzag planting) in the main plot, irrigation with three levels [control (without stress), irrigation as 80% of required water (as deficit irrigation treatment), and irrigation as 60% of required water (as stress treatment)] in sub plots, and potassium fertilizer in three levels (0 (control), 75 and 150 kg potassium sulfate per hectare) as sub-subplots. Potato crop water requirement based on the amount of water needed which has been specified using OPTIWAT software under Rokh plain conditions, was determined. Drip irrigation methods using tapes was conducted. The data was analyzed using the SAS program, the FLSD method was used to compare the means. All graphs were drawn using Excel software.
The results of the experiment showed that there was a significant difference between irrigation treatments for plant height, so that reducing water amount significantly reduced the plant height. The shortest and tallest plants were observed with stressed and control treatments, respectively. The number of stems produced in different treatments did not show significant differences.
In this research, zigzag planting pattern under complete irrigation and consumption of 150 kg of potassium sulfate increased the maximum leaf area compared to common and dense common planting patterns. Moreover, the comparison of the mean for the interaction effect of cultivation pattern and potassium sulfate fertilizer on the dry weight of maximum leaf area showed that zigzag planting pattern and consumption of 150 kg ha-1 of potassium sulfate fertilizer, enhanced the dry weight of maximum leaf area compared to common and dense common planting patterns without potassium sulfate fertilizer.
In this study, zigzag planting pattern under complete irrigation and consumption of 150 kg of potassium sulfate fertilizer resulted in the greatest relative water content of leaf. The Irrigation rate had a significant effect on the dry matter percentage, so that water stress caused a significant reduction in dry matter percentage. In fact, the dry matter percentage under water stress conditions was reduced by 12% compared to the control treatment.
In this experiment, the number of tubers in common and dense common planting patterns with complete irrigation and consumption of 150 kg of potassium sulfate was 15% greater than that of zigzag planting pattern and 150 kg potassium sulfate consumption.
Comparison of the mean for the interaction effect of planting pattern on irrigation rate and potassium sulfate fertilizer showed that the greatest number of non-marketable tubers was observed with the common planting pattern under water stress and no potassium sulfate fertilizer application and the lowest was obtained where the zigzag planting pattern was applied with full irrigation and consumption of potassium sulfate fertilizer.
Yield measurement in this experiment showed that there was a significant difference between the levels of cropping pattern, irrigation and potassium sulfate rates. The tuber yield was enhanced by changing from usual to zigzag cultivation pattern and was reduced by lowering the irrigation rate, while application of potassium sulfate fertilizer increased this trait and this, reduced the effects of stress in all tested planting patterns.
It seems that the pattern of zigzag cultivation in potatoes can increase plant yield and on the other hand, due to the sensitivity of the potato plant to irrigation rate, providing enough water improved its performance. The remarkable thing was that application of potassium sulfate fertilizer increased and improved the quality and yield of the tubers under water stress conditions.

Salinity is one of the most important abiotic stresses that cause severe effects on crop production around the world. Estimates indicate that more than 800 million hectares of arable lands in the world are affected by salinity. Salinity impacts on various aspects of growth from germination to seed production in plants. Plants′ responses to salinity, however, are different and depend on the toxicity, osmotic potential, as well as the stress duration. Purple nutsedge (Cyperus rotundus L.) is one of the noxious weeds. This weed belongs to sedge family, and is a C4 perennial plant which reproduce by sexual (seeds) and asexual (tubers and rhizomes) means. It can cause tremendous damage on summer crop fields such as onion, potato, maize, sunflower, and so on. Evaluation of weed growth responses to saline condition came about by water and soil can provide for us very important information by which we choose appropriate weed control strategies. Since a few experiments have been evaluated growth characteristics of purple nutsedge under salinity stress, this study was conducted to evaluate the salinity effects on growth characteristics of purple nutsedge.
Material and To evaluate the effect of irrigation water and soil salinity on growth characteristics of purple nutsedge, two separate experiments were conducted in a randomized complete block design with three replications in the greenhouse of Faculty of Agriculture at University of Birjand in 2013. The first experiment contained five salinity levels of water including 0, 3, 5, 7 and 9 dS.m-1 and in the second experiment, there were five salinity levels of soil including 1, 3, 5, 7 and 9 dS.m-1. The salinity levels of water were prepared through solving a certain amount of NaCl in water based on this equation: NaCl (mg. L-1) =EC (dS.m-1)×640.. Following determination of soil electrical conductivity, soil salinity levels were prepared by adding NaCl to the soil based on saturation moisture percent and field capacity. A tuber of purple nutsedge was planted at 2.5 cm depth in each pot. Experiments were terminated at the end of the vegetative growth stage of purple nutsedge (105 days after emergence). Measured traits were plant height, stem number per pot, leaf area, and tuber number per pot, shoot and underground dry weight. After collecting the data, ANOVA was performed using Genstat Ver. 9 and mean comparisons were performed using Fisher's least significant difference test at 5% significant level. In order to evaluate purple nutsedge growth response to salinity stress, an exponential decay model was used; Y=a*exp(-b*x), thta in this model, a and b represents the maximum amount of studied traits and the slope of curve according to the model estimation, respectively.
The results of both experiments showed that the growth characteristics of purple nutsedge (plant height, stem number per pot, leaf area, tubers number per pot, shoot and underground dry weight) were significantly affected under soil (P