نشریه پژوهشهای زراعی ایران
سال پنجم شماره 2 (پیاپی 10، پاییز و زمستان 1386)

In order to examine the effect of desiccation and freezing on Russian knapweed,s (Acroptilon repens) root regrowth, two experiments on basis of completely randomized design were conducted in Weed Research Department, Plant Pests and Diseases Research Institute of Tehran in 2003.To examine the effect of desiccation, the first experiment was a factorial arrangement with 4 replications. First factor (A) was desiccation length time (control, 24, 48, 96 and 192 hours), and second factor (B) was desiccation temperatures (5, 15 and 25˚C). To examine the effect of freezing, second experiment was also a factorial arrangement with 4 replications. First factor (A) was the freezing length time (control, 24, 48 and 96 hours) and second factor (B) was freezing temperatures (-1, -3 and -5˚C). In the effect of desiccation experiment on root regrowth, factors A and B were significant on all of measured characters (water loss percent, shoot numbers, dry weight, leaf number and shoot length). Increasing in temperature and length time of desiccation, leads to low regrowth. The interaction effect (AB) on water loss percent, shoot number and shoot length was significant. Regrowth stopped in 5˚C after 96 hours desiccation and in 15˚C and 25˚C after 24 hours. In freezing experiment, factors (A), (b) and their interaction were significant on all of measured characters (shoot number, leaf number and shoot length).Decreasing in temperature and increasing of freezing length time, leads to low regrowth. Regrowth reduced in -1˚C after 96, 48 and 24 hours respectively. But stopped in -3˚C and -5˚C after 48 and 24 hours freezing, respectively.

In order to study the effects of irrigation with different levels of urban treated waste water on feeding value of forage sorghum (Var. Speed feed and Sugar graze), maize (Var. SC 704) and millet (Var. Nutrifeed) an experiment was conducted at Experimental Station No.1, Astan Qods Razavi Mashhad, and Animal Nutrition Laboratory, College of Agriculture, Ferdowsi University of Mashhad. Four varieties of forage plants with five levels of treated waste water: %0, %25, %50, %75 and %100 were compared in a split-plot experiment based on Randomized Complete Block Design with four replications per treatment. Feeding values of forage plants such as Crude Protein content (CP), Neutral Detergent Fiber content (NDF), in vitro Dry Matter Digestibility (DMD), Organic Matter Digestibility (OMD) and D-Value were measured. Results showed that treated waste water irrigation had a significant effect on crude protein content. The highest crude protein content was shown at % 100 treated waste water (%13.76) and the lowest was shown at % treated waste water (%9.54). There were no significant differences between %0 and %25, and also %75 and %100 treated waste water in terms of crude protein content, but there were significant differences between %50 and other treated waste water treatments (except 75% treatments). There were no significant difference between irrigation with different levels of treated waste water in terms of NDF, in vitro DMD, OMD, and D-Value. There were significant differences between forage plants in all studied characteristics, but there were no significant differences on interactions between forage plants and different levels of treated waste water treatments. Forage maize had the highest in vitro DMD at %75 treated waste water and forage sorghum (var. Speed feed) had the lowest in vitro DMD at %0 treated waste water treatments with averages of %77.57 and %61.6, respectively. The results indicated that treated waste water increased the percentage of crude protein content but there were no any change in terms of NDF, DMD, OMD and D-value.

In order to determine optimum planting date and best cultivar of Amaranth, a field experiment was conducted in 2005 on agricultural Faculty of Ahvaz. The experimental design was a randomized complete block with a split plot with three replications. Main plot were assigned to three planting dates (i.e. 4/10, 4/15 & 5/1) and sub-plot were assigned to four amaranth cultivars (i.e. Slovaky, Plaintsent, Mercado & Amonth). Results showed that change in planting date had a significant effect on most quality and quantity components of forage yield. Mercado CV. in second planting date had the highestforage yield. Highest stem weight was a main reason for yield priority. Despite of lowest yield, highest protein content was obtained by Amount cv. in third planting date. Therefore, Mercado cv. and second planting date could be recommended for planting Amaranth crop in Ahvaz.

A high correlation existes between crop growth and the rate of radiation intercepted. The efficiency of radiation interception and absorption is dependent on leaf area index, light extinction coefficient and radiation use efficiency. In order to study mentioned coefficients a randomized complete block design with four replications was conducted during 2005 for different sugar beet cultivars (7233, 7112, 436, 276 and Rasoul) at Ferdowsi University of Mashhad experimental farm station. The cultivars were cultivated in eight rows with 50 centimeters distance in plots with 12 meter length and optimum condition of nutrients and irrigation. In addition to measuring the radiation above and under the canopy, the plots were sampled 9 times during growing season and leaf area index, total dry matter and finally light extinction coefficient and radiation use efficiency were measured. Mean maximum leaf area index was 3.51. The final yield of total dry matter for different genotypes varied from 15670 to 25920 kilogram per hectare. There were no significant differences among genotypes in light extinction coefficient and radiation use efficiency and their mean values were about 0.56 and 1.23 g.Mj-1, respectively. Seasonal variation of radiation use efficiency was similar to leaf area index changes during the crop growth cycle and maximum radiation use efficiency was located before the reaching of maximum green leaf area index. Sugar content was increased proportional with total and root dry matter in most of crop growth cycle. Considering the importance of light extinction coefficient and radiation use efficiency in crop growth models and also their spatio-temporal variability under different management, it is necessary to perform more experiments in different years and locations with various treatments, to obtain a range of these coefficients for modeling studies.

To evaluate the effect of different management on composition, density and distribution patterns of prostrate pigweed and red root pigweed seed banks, an experiment was conducted in a grain corn field at the Agricultural Research Station, Ferdowsi University of Mashhad in 2006 growing season.The treatments consisted of application of: 25 kg/ha nitrogen fertilizer at the time of corn planting with 2,4-D+MCPA herbicide(533 g. ai./ha 2.4.D+467 g. ai./ha MCPA), 25 kg/ha nitrogen fertilizer at the time of corn planting without 2,4-D+MCPA, 25 kg/ha nitrogen fertilizer at the time of corn planting and six-leaf stage with 2,4-D+MCPA, 25 kg/ha nitrogen fertilizer at the time of corn planting and six-leaf stage without 2,4-D+MCPA, 120 kg/ha nitrogen fertilizer at the time of corn planting with 2,4-D+MCPA, 120 kg/ha nitrogen fertilizer at the time of corn planting without 2,4-D+MCPA, 120 kg/ha nitrogen fertilizer at the time of corn planting and six-leaf stage with 2,4-D+MCPA and 120 kg/ha nitrogen fertilizer at the time of corn planting and six-leaf stage without 2,4-D+MCPA.The percentage of Amaranthus blitoides seed free spaces was zero throughout the season. Application of herbicide was useful in reducing A. blitoides seed bank. Semivariograms of seeds fitted with spherical and exponential models.Semivariogram analysis in the levels of treatments indicated a range of influence of 1.17m to 50.21 m for prostrate pigweed and 1.15m to 44.98m for red root pigweed. The highest spatial correlation for prostrate pigweed was 1.91% and the lowest one was 32.37%. Weed seed bank patches was obvious in two species maps.The nitrogen fertilizer have not a strong effect on reducing the amount of seed bank but the application of herbicide was a useful factor to reducing weed seed bank.

In order to investigate the germination characteristics and cardinal temperatures of Thymus transcaspicus, a laboratory experiment was conducted with two different cultivated and natural seedlots at constant temperatures including 2, 5, 10, 15, 20, 25, 30, 35, 40 and 45 °C in a completely randomized design with four replications. Two seedlots were monitored for variability in germination criteria based on three regression models namely: Five-parameters Beta (FPB), Intersected-lines (ISL) and Quadratic Polynomial (QPN) models. The effect of temperature on rate and percentage of seed germination in both seedlots was significant. For both seedlots the highest germination percentage (GP) was within the range of 10-30 °C while the highest germination rate (GR) occurred in 30 °C. Although means of GP and GR for the field seedlot were higher than the natural seedlot, variability of GP and GR in response to temperature was higher for natural seedlot. Best model fit over the entire temperature range was obtained by the FPB and ISL models for both seedlots. However, FPB model showed most suitable fitness particularly in the case of natural seedlot. Based on the regression between germination rate and temperature in both seedlots, the cardinal temperatures (Tbase, Topt and Tmax) were: (1.2-3.84), (29.1-25.8) and (45-47) °C for field seedlot and (1.0-3.3), (24.9-29) and (45-46) °C for natural seedlot, respectively.

In order to evaluate responses of grain yield and yield components of wheat to different amount of supplemental irrigation in dryland conditions, a field experiment was conducted in research farm of College of Agriculture, Shiraz University during 2004-2005 and 2005-2006. The supplemental irrigation treatments including dryland conditions, irrigation at stem elongation, booting, flowering and grain filling were main plots and two cultivars, Agosta and Fin-15 were subplots and three levels of nitrogen including zero, 40 and 80 kgha-1 were sub sub plots. The results showed that in both years, the highest number of spike m-2, spikelet spike-1, number of kernel spike-1 and grain yield were obtained from irrigation at stem elongation stage whit 80 kg N ha-1 and from Fin-15 variety and the lowest were obtained from Agosta variety at N control treatment under dryland conditions. Also the highest thousand kernel weight was obtained from supplemental irrigation at grain filling stages.. The results of this research showed a strong correlation between number of spike m-2, spikelet spike-1, number of kernel spike-1, thousand kernel weight and grain yield with the amounts of applied water at supplemental irrigation treatments and whit increasing of applied water the above mention parameters also increased. The highest grain yield in both years was obtained from supplemental irrigation at stem elongation stage. The supplemental irrigation in 2004-2005 and 2005-2006 growing season increased the grain yield 200 and 221 percent respectively. According to results of this experiment, supplemental irrigation increased wheat production through increasing yield and yield components in dryland conditions. Thus using of supplemental irrigation at stem elongation stage with supply of adequate water could increase grain yield of rainfed wheat in dryland conditions.

Determination of optimal plant density and cultivar selection is one of yield increment approaches in grain sorghum. In this in regard, a field experiment with factorial arrangement in randomized complete block design (RCBD) with tree replicates was done at Birjand in 2003. In order to evaluate the effects of plant desity (100000, 180000 and 260000 plant/ha) on seed yield, yield components, and some physiological traits in 4 grain sorghum varieties (Sepideh, Saravan Local, Payam and Kimia). The results showed that the density increment (from 100000 to 260000 plant/ha) had advantage for seed yield. However, the lower density, due to reduction of plant competition, resulted in a significant increase in single plant yield, number of seeds per panicle, remobilization percentage of different parts of stem and stem remobilzation percentage. The highest stem remobilization percentage belonged to top of stem internode. Effect of density was not-significant on traits such as chlorophyll index and 1000 kernel weight. Cultivars were significantly different in all of studied traits. Intreaction between variety and density was significant on stem remobilization percentage and number of seed per panicle. There was a significant relationship between grain yield, 1000 kernel weight (r = 0.73**) and number of seed per panicle (r = 0.62**). It was concluded that Saravan local variety with grain yield of 12.75 ton/ha and density of 260000 plant/ha were the best combinaton of tratments

To study the effects of different manure levels and two branch management methods on organic production of Schneider squash, an experiment was conducted at research farm of Ferdowsi University of Mashhad, during years 2004-2006. A split plot arrangement based on Randomized Complete Block Design with three replications was used. Treatments consisted of four manure levels (10, 15, 20, 25 tones/ha) and two branch management methods (with and without wood pole), which were allocated to main plots and sub plots, respectively. Results showed that branch management method without wood pole was better than branch management method with wood pole. The first year results showed that increases in manure level had significant effect on fruit and seed yields

Fallow is used to increase soil moisture under rainfed conditions, but its effectiveness is dependent on climate and soil conditions of each region. Simulations were performed to evaluate fallow at 5 locations in east Azarbaijan (Ahar, Maragheh, Minab, Sarab and Tabriz) using 23 years weather data. Results indicated that at the end of seasonal fallow (SF: form September to March) 79-140 mm water is stored, which is 50 to 60 % of precipitation. Soil evaporation was the most important loss that resulted in 40 to 50 % loss of precipitation. Contribution of runoff and deep drainage was relatively low and similar (between 1 to 10 %) in water loss. In yearly fallow (YF: form September to September) soil moisture stored was between 67 and 104 mm which consisted 16 to 31 % of total precipitation. Comparison of SF and YF indicated that YF does not have any advantage with respect to soil moisture storage, but resulted in considerable moisture losses via runoff and deep drainage. And hence soil erosion and nutrients leaching. Simulation results also showed that application of straw mulch (0.5 to 2 t/ha) does not have any advantage in SF or YF.

In order to evaluate the interference of wild mustard on growth indices of Canola cultivars an experiment was carried out in Agricultural and Natural Resources Research Institute of Gorgan during 2005-2006 growing season. The experiment was established as a randomized completely block design in a factorial arrangement of treatments with three replications. Canola cultivars, Zarfam, Sarigol, Talayh, R.G.S 003, Option 500, Hayola 401 and Hayola 330 were kept under weed free and weed infested conditions. The results indicated that, wild mustard resulted in reduction of canola dry matter, leaf area index, leaf area index duration and crop growth rate, significantly. The maximum dry matter, leaf area index and crop growth rate in control plots (weed free treatment) belonged to Hayola330 cultivar. The maximum and minimum reduction rate of dry matter and leaf area index of canola cultivars was obtained in control Option500 and Zarfam cultivars respectively. Results revealed, cultivars with higher leaf area index, relative leaf area expansion rate and better vertical leaf area distribution could be more competitive in weed-infested conditions, and can be used in breeding programs to enhance competitive ability of canola cultivars.

Efficient use of nitrogen for medicinal plants production, might increase flower dry matter, essential oil and extract yield and reduce cost of yield production. A two year (2005 and 2006) field study was conducted in Torogh region(36,10° N,59.33° E and 1300 m altitude) of Mashhad, Iran, to observe the effects of different nitrogen and densities on flower dry matter, essential oil and extract production and nitrogen use efficiency (NUE) in a multi-harvested Marigold (Calendula officinalis). The levels of Nitrogen fertilizer (N) were 0, 50, 100 and 150 kg ha-1 and levels of density were 20, 40, 60 and 80 plant m-2. The combined analysis results revealed significant effects of N and density levels on flower dry matter, essential oil and extract production and NUE of Marigold. The highest dry flower production obtained by 150 kg ha-1 N and 80 plant m-2 plant population (102.86 g m-2). The higher flower dry matter production caused more essential oil and extract production in high nitrogen and density levels. Agronomic N-use efficiency (kg flower dry matter yield per kg N applied), physiological efficiency (kg flower dry matter yield per kg N absorbed) and fertilizer N-recovery efficiency (kg N absorbed per kg N applied, expressed as %) for marigold across treatments ranged from 6.8 to14.9, 12.3 to 33.6 and 55.5 to 77.6, respectively and all were greater for N application at 50 compared with150 kg N ha-1, and under high density than low density. The amount of essential oil and extract per 100g flower dry matter decreased during the flower harvesting period. The higher amount of essential oil and extract obtained at early flowering season. The essential oil and extract ranged from 0.22 to 0.12 (ml. per 100g flower dry matter) and 2.74 to 2.13 (g per 100g flower dry matter) respectively.

To investigate the effect of sowing date and plant density on yield and yield components of safflower (Carthamus tinctorious) as well as evaluating the possibility of the second sowing of the plant in Torbat Heidariyeh, a field experiment was conducted in Rokh, Cold Season Cereal Research Station 2005. The experiment was conducted in split plot arrangement in complete randomized block design with four replications. Main plots were sowing date in five levels including 9 April, 10 May, 31 May, 20 June, 11 July and sub plots were plant density in three levels including 300000, 400000, 500000 plants per hectar. Some charactristics such as the number of capitulum per square meter, seed number in capitulum, seed weight, harvest index and seed yeild was evaluated.The highest seed yield was obtained in first sowing date in 3347 kg/ha and a delay in sowing date resulted a decrease in yield. The cold weather in (05/11/2005) caused flower fertility not accured, consequently, sowing was not successful. Results showed that the effect of sowing date on yield depends on the number of capitulum per unit area and the number of grains per capitulum. These two characteristics in th first sowing date in respect of the other dates were higher. The effect of density on yield was significant resulted on yield increase due to capitulum increase in unit area. As a result, the first sowing date with the highest density is recommended. However, The third and fourth sowing date can be considered as the second planting in a sequeational cropping system.

There are three hierarchical steps to fill the yield gaps in agricultural systems. These steps are determination of potential yield, yield gaps and system optimization to fill yield gaps. In this study a simple mechanistic model was developed and tested to determine potential yield and yield gaps of Cumin (Cuminum cyminum) in nine regions of Khorasan provinces (including Bojnourd, Qaeen, Mashhad, Neishabour, Sabzewar, Gonabad, Ferdous, Kashmar and Birjand). Collected data of related year from 228 fields were used to calculate yield gaps. Results indicated variable potential yields in different climatic conditions (the areas with cooler climate and higher radiation had higher potential yields). Also, yield gaps varied considerably between regions (from 2.42 ton.ha-1 in Bojnourd to 0.68 ton.ha-1 in Sabzewar). The highest value for potential yield belonged to Bojnourd (3.7 ton.ha-1). The collected data from studied fields and sensitivity analysis on sowing date (based on common sowing dates range) showed that inappropriate sowing dates was one of the most important yield reducing factors in all regions. Results revealed that if the yield gaps can be filled based on appropriate management option, yield can be increased by two to three folds in some regions.

The dynamic of root growth of chickpea genotypes; including Rupali (Desi) and Flip 97-530 (Kabuli) were evaluated under waterlogging stress in a Glasshouse experiment at CSIRO, Perth, WA. during 2005. Root growth boxes (0.1×0.24×1.0 m) with one wall of glass were used as experimental units. Data were analyzed based on Randomized Complete Block Design with three replications. Waterlogging was induced when the first root reached 50cm. The water level was maintained on the soil surface for 12 days. After that, waterlogging was finished by draining the root growth boxes. In soil profile, root growth rate were calculated based on recorded information on transparent films during growing season. There was positive and strong linear correlation between the root traits that were measured in soil (direct measurment) and transparent films (indirect measurment). Decay and death of roots caused a severe decrease on root growth rate during waterlogging, but root growth rate was sharply increased at the end of recovery period on 0-40 cm layer of soil surface. In both genotypes, spatial and temporal patterns of the root growth were different. Root growth rate was highest on distinc time for each layer of soil profile. In both genotypes, RLD decreased with increasing soil depth. Results showed that more distribution of root system on upper soil layers (0-40 cm) is a strategy for chickpea plants, and so, soil management is very important on this layer. In stress and non stress environments, Flip 97-530 showed better root characteristics than the Rupali during growing season, so this genotype is probably more tolerate to water logging stress.

In order to study the effects of potassium amounts and methods of potassium application in different systems of tillaging on barley cultivar of Karoon*Kavir grain yield in salinity stress conditions, a farm trail was conducted in a split block arrangement in three replications with a Randomized Complete Block Design at Roodasht salinity and drainage research station (Esfahan province) in 2003-5. Experimental treatments were soil tillage systems, potassium fertilizer amounts and its, placement methods. The main plots were soil till systems (conventional, minimum and no tillage).The horizontal treatments were recommended (300 kg/ha potassium sulfate), 33% lower and 33% higher than recommended amounts of potassium fertilizer. The vertical treatments in main plots were fertilizer placement methods (spreading and strip replacement of fertilizer 5 centimeter under the seeds). The water salinity of irrigation after spring growth stage was 12 ds/m. The conventional irrigation before spring growth stage is river water supply. The ANOVA results showed that: In the first year of study, the different soil till systems effected significantly(p = 0.01) plant height, number of spike per square meter, the concentration of minerals in leaf, grain yield, biological yield and harvest index. The fertilizer applications and its, placement effects on above-mentioned traits were not significant. The highest grain yield (3213 Kg/ha) obtained in conventional till. In the second year of experiment: soil tillage systems, the potassium fertilizer amounts and fertilizer placements had no significant effect on grain and biological yields of barley cultivar. The two-year study results showed that: The conventional till system is a suitable method for planting barley in soils with clay loam texture. In spite of higher amounts of potassium fertilizer application and higher amount of absorbable K+ in the soil, there were no significant effect on grain yield and its components.