Iran Agricultural Research
Volume:39 Issue: 2, Summer and Autumn 2020

ABSTRACT-Zeolite is used to improve the soil hydraulic properties, i.e., soil hydraulic diffusivity (D) and sorptivity (S) that should be determined. A simple method that relates S to D was evaluated by horizontal water absorption experiment in sandy loam, loam and silty clay soils and zeolite application rates of 0, 4, 8, and 12 g kg-1 soil. Results indicated that zeolite application was not effective on the a and b values of hydraulic diffusivity function (D=aEXP(bθ), θ is the soil water content, cm3 cm-3), while maximum value of a and b in sandy loam and silty clay soils, respectively occurred by zeolite application of 8 g kg -1 soil. The values of a and b for loam soil were not influenced by zeolite application rates. Sorptivity for sandy loam soil was reduced by zeolite application rate, while minimum value of S for loam and silty clay soils occurred at zeolite application rate of 8 g kg-1 soil. It is indicated that indirect determination of S for different soil textures and zeolite application rates were closely similar to the direct determination of S. Therefore, by determination of S value by simple horizontal absorption test at two different initial soil water contents or two different absorption suction heads in tension infiltrometer  the values of Ds and α for hydraulic diffusivity function (D=Dsθα) can be estimated.

ABSTRACT-A field study was conducted to determine the influences of six mulch materials (organic and inorganic), including black plastic, transparent plastic, wheat straw, peat moss, coco peat, and sawdust and the metribuzin on the two weed species vegetative and reproductive growth cycles in a tomato field using a randomized complete block design with three replications at the Research Station of the Agricultural School, Shiraz University, Shiraz, Iran. According to the results of the analysis of variance, all evaluated traits of both weed species, and also tomato, were significantly influenced by treatments at p < 0.01.The longest and shortest time of redroot pigweed (Amaranthus retroflexus L.) emergence were recorded under the plastic mulch treatments at 28 days after transplanting (DAT) and organic mulches as well as metribuzin at 21 DAT, respectively. Plastic mulches deferred the time of lamb's quarters (Chenopodium album L.) emergence more than organic mulches up to 28.0%. Additionally, the longest time of lamb'squarters emergence was observed with coco peat at 29 DAT and the shortest time of its emergence was recorded under the application of clear plastic and sawdust mulches at 23.3 DAT. Results showed that, the highest marketable tomato yield (up to 19.2 kg m-2) was assessed in covered plots with black plastic mulch, while the lowest marketable yield was detected by 3.02 kg m-2 in the plots under the application of the sawdust treatment. In general, results demonstrated that the plastic mulches, particularly the black plastic sheet, could be reliable alternatives for metribuzin to control weed infestations in tomato fields.

To investigate the amount of yield losses caused by Iranian  isolates of tomato yellow leaf curl virus (TYLCV-[Ab]) and tomato leaf curl Karnataka virus (ToLCKV-IR) in Rio Grande (RG) and Grosse Lisse (GL) tomato cultivars, tomato seedlingswere separately agroinoculated with  an infectious clone of either virus and disease development was monitored over four time intervals. After the emergence of symptoms, disease severity (DS) was evaluated visually using an ordinal rating scale and the data was converted to a ratio scale. Losses caused by the viruses were estimated by measuring vegetative indices including wet and dry weight and height of the aerial and underground parts of the plants. Initial DS in plants infected by ToLCKV-IR was less than those infected by TYLCV-[Ab]. Descending order of rates of disease increase for the studied pathosystems was as follows: ToLCKV-IR-infected GL>TYLCV-Ab-infected GL> TYLCV-[Ab]-infected GL> ToLCKV-IR-infected RG. With delayed inoculation, DS was reduced in both cultivars inoculated with either of the two viruses. A segmented linear model showed a very good fit to the data of relative biomass and duration of exposure of all pathosystems. The estimated parameters of the model were used to evaluate different aspects of the damage curve. The highest crop loss disease threshold was observed for GL cultivar irrespective of the inoculated virus. Similar results were achieved when the desensitization disease level was evaluated. Curvilinear tolerance or slope did not show any significant difference between the infected-GL plants to either virus and also TOLCKV-IR-RG, while TYLCV-[Ab]-RG showed the highest curvilinear tolerance. Findings of this study can be applied in screening for tolerant tomato plants.

In this study, the effect of supplemental irrigation timing (treatments included no supplemental irrigation; supplemental irrigation in middle of March; supplemental irrigation in early May; supplemental irrigation in early August; and two supplemental irrigation events in middle of March and early May) and potassium (K) application (treatments included no-fertilizer; 150 and 250 g fertilizer per tree applied by fertigation method and no-fertilizer; 1.5 and 3.0 kg fertilizer per 1000 L water used by foliar application) on yield and yield quality of rain-fed fig trees were studied at the Estahban fig orchards in Fars province, Iran, through a three-year experiment. Results showed that supplemental irrigation for fig resulted in an increase in yield and fruit size, and improved the fruit peel color. However, it decreased total soluble solid of fruit. For one irrigation during the growing season, irrigation in late winter (March) with 1250 L of applied water per tree was better than irrigation in spring (May) with a similar amount applied water which was used as the supplemental irrigation of rain-fed fig trees under severe drought conditions. Two irrigation in March and May with 1500 L and 1250 L of applied water per tree for each event for the first year and two subsequent years, respectively, was more effective on the yield and fruit quality than single irrigation due to higher applied irrigation water. Using 150 g K per tree by fertigation method or 3.0 kg/1000L foliar K fertilizer resulted in significant effect on the yield and yield quality of fig and improved them.

Water stress has been identified as the major effective factor on soybean production growth in semi-arid regions. Planting date and irrigation management are the most important agronomic practices, which affect soybean growth and economic yield production. Today, to assess the impacts of destructive environmental stresses, calibrated models can be used to simulate and evaluate the growth of the crops under different scenarios. In this research, the AquaCrop model was evaluated for simulation of soybean yields and water productivity on varying irrigation levels and planting dates in northeast of Iran. For this purpose, root mean square error (RMSE), model efficiency (E), coefficient of determination (R2), and prediction error (p e) were applied to test the model performance. The calibrated AquaCrop model predicted soybean grain yield and biomass for all treatments with the prediction error statistics 0.27<RMSE-1, 5.1 e<5.6%, 0.91<R2-1 ha-1, R2 of 0.88, and p e of 7.6%. Subsequently, validation results were 0.93<E<0.96; 0.92<R2-1 for grain and biomass yield, respectively. The soybean yields and growth response to different irrigation water management and planting dates was adequately predicted by the AquaCrop model. Overall, the AquaCrop model is a suitable support tool for decision makers to simulate WP, grain yield (GY), and biomass (Bi) in soybean cultivation under various field managementin semi-arid environment.

Cultivation of globe artichoke (Cynara cardunculus var. scolymus L.), as a multipurpose species of vegetable, medicine and green forage, along with using biological fertilizers and reduced rates of chemical fertilizers is arranged within sustainable cropping systems. In order to study the effects of chemical and biological fertilizers and integratedplant nutrientsystems on some traits of globe artichoke, a factorial experiment was conducted on the basis of randomized complete block design with three replications in Isfahan, Iran in 2014. Factors included chemical fertilizers at the levels of control (no fertilizer), 100 and 50 % of the recommended amounts, and bio-fertilizers at levels of control (no bio-fertilizer), Nitroxin (Azotobacter, Azospirillium andPseudomonas), Barvar 2 (Pseudomonas putida-p13and Pantoea agglomerans-p5) and Nitroxin+Barvar 2. Morphological traits, chemical composition, metabolizable energy and net energy for lactation were determined at the vegetative rosette stage. Results indicated that using bio-fertilizer and chemical fertilizer significantly improved effective parameters in increasing forage quality. Inoculation with two bio-fertilizers increased more forage quality than those of single application of them. However, Nitroxin had more positive effects than Barvar 2. In general, it was concluded that integratedplant nutrienttreatmentsare more beneficial effects on the growth and quality of globe artichoke forage.

Understanding the interactive effect of water and nitrogen (N) availability is a crucial issue for stabilizing cereal forage production in the arid areas. A two-year side by side experiment (2015-2016 and 2016-2017 growing seasons) was carried out under different N sources and water regimes in a typical arid environment (Darab, Iran) to evaluate the forage quality of triticale (×Triticosecale Wittmack) crop.There were two irrigation regimes [normal irrigation (IRN) and cutting off irrigation after crop anthesis stage (IRMD)]. Rain-fed treatment (IR0) was included in the second year. Three N sources including Azospirillum brasilense (biofertilizer, Bio), Azospirillum brasilense + 75 kg N ha-1 as urea (Bio + N75), 150 kg N ha-1 as urea (N150) and unfertilized plots (N0 ascontrol) were used. Water stress decreased leaf-stem (L/S) ratio, dry mater (DM) and dry matter digestibility (DMD) and increased crude forage protein (CP), neutral detergent fiber (NDF) and ash contents. However, the effect of water stress on forage ash, DMD, ADF contents, L/S ratio (in 2015-2016 growing season) and CP content depended on N sources. In Bio + N75, triticale forage had the highest CP content, DMD, ash and L/S ratio (in 2015-2016 growing season) and the lowest ADF compared with the other N sources under water stress conditions. According to the results of this study, it can be suggested that the integration of biofertilizer and chemical N fertilizer be successfully used to increase the quality of triticale forage under deficit irrigation regimes in sustainable farming systems in arid conditions.

ABSTRACT- This study was conducted to introduce agro-physiological traits for improving drought tolerant rapeseed winter genotypes for cultivation in saline areas. Eighteen rapeseed genotypes were evaluated under non-stressed and drought-stressed conditions from flowering and seed filling stages to seed maturity for two years (2012-2014) at the saline soils (EC=6.7 dS m-1) in Agricultural and Natural Resources Research and Education Center of East Azarbaijan, Iran. Drought stress significantly decreased pod length, plant height, seed yield, yield components and stomatal conductance and increased canopy temperature.Among the genotypes, significant differences were observed for pod length, the number of seeds in a pod, seed and oil yields, and stomatal conductance. The correlations among the traits were significantly positive. According to the results of genotypes grouping, HW101, L183, L73, and L72 having higher pod length, the number of seeds in a pod, stomatal conductance, seed and oil yields, which were recognized as the promising ones. The results of this study indicated that, the pod length, the number of seeds in a pod and stomatal conductance as simple and easy parameters can be used to select late season drought tolerant rapeseed winter genotypes for cultivation in saline areas. Also, the cluster analysis method was able to discriminate productive genotypes. Water deficit during flowering and seed filling stages, decreased the mean of seed yields by 800 and 584 Kg h-1 during the first year and 1764 and 1154 Kg h-1 during the second year of the experiment, of this study respectively. Thus, it was concluded that the evaluated rapeseed genotypes at the flowering stage were more sensitive to drought compared to the seed filling stage.

Phosphorus (P) is a nutrient essential for plant, which its availability in soils changes with aging process, leaching, precipitation processes, and the landform change. There is limited information available on kinetics release of P in calcareous soils. Therefore, the purpose of this study was to investigate distribution of P and the effect of physicochemical properties and clay minerals on its release in some dominant orders of the calcareous soils in Kohgiluyeh-and-Boyer-Ahmad province, using the 0.01 M calcium chloride ( ) extractant. The results showed that the P released rapidly from the soil and continued slowly. After 72 h, the amount of P released in the studied soils ranged between 3.2 and 25.4 mg kg-1. Evaluation of the fitted different equations on P released in the studied soils revealed that the Simple Elovich and power function equations could well predict the P release process in the studied soils. The results of the correlation between soil properties and released P contents showed that P release coefficients (including the slope and intercept in the Simple Elovich equation) have a significant negative relationship with the amount of smectite and vermiculite minerals. Also, the release coefficient of the parabolic diffusion equation had a significant negative relationship with pH and the amount of illite and palygorskite minerals.

ABSTRACT - Tahini is an important product of peeled sesame. As a byproduct of oil extraction from tahini, tahini meal (TM) is a valuable protein source. However, it is only used to feed livestock. TM can be used as an affordable protein source in human diet. In this research work, the effects of extraction pH (10, 11 and 12) and isoelectric pH (4.5, 5.5 and 6.5) on functional and thermal properties of proteins isolated from TM were studied. Functional properties of extracted proteins including water and oil absorption, foaming capacity and foam stability as well as thermal properties were measured. The results showed that the highest protein extraction efficiency (87%) was obtained in extraction pH at pH≥11 and isoelectric pH 6.5. In addition, the highest levels of water and oil absorption capacity were obtained in proteins precipitated at pH 6.5 (p ≤0.05). The highest level of foaming capacity and stability was observed in proteins extracted at pH11 and precipitated at pH6.5. On the other hand, thermal properties of TM protein including onset denaturation temperature (Tm), denaturation peak temperature (Td) and denaturation enthalpy (ΔHd) were affected by sediment pH and pH 6.5 led to the highest thermal characteristics. Since the optimum characteristics of proteins isolated from TM were obtained at isoelectric pH 6.5 and extraction pH 11, these pH values are recommended for the extraction and precipitation of TM proteins, respectively.

Bio-fertilizers are microbial inoculants or a combination of carriers of effective microbial strains with high efficiency to provide one or more nutrients needed by the plant, which are important materials as reducing agents to reduce the environmental damage of chemical fertilizers, to reduce diseases, to improve the soil structure, to stimulate plant growth and to increase the quantity and quality of the crops. This study was conducted to investigate the effect of three commercial bio-fertilizers, including Pseudomonas aeruginosa, P. putida, and P. fluorescens, on some morphological and physiological traits of lettuce under greenhouse conditions. The experiments were held on Nuclear Agriculture Research School in a completely randomized design (CRD) with four replications. The results indicated that inoculation of lettuce at growth stage with these biological fertilizers caused a significant increase in plant growth components such as plant height, leaf number, plant diameter, dry and fresh weights. In the case of physiological indicators, the use of bio-fertilizers increased expression of total protein, and also improved the production of oxidative enzymes (peroxidase and polyphenol oxidase) in the leaf compared to the control. According to the results of this study, it can be concluded that the use of bio-fertilizers contributes to the development of organic agriculture which in turn improves the quantity and quality of the product.

Planting pattern and plant density are efficient management tools for maximizing crop yield by reducing soil surface evaporation and optimizing resource utilization such as light, nutrients, and water. A two-year (2017-18) field trial was conducted to determine the effects of plant density and planting pattern on some agro-physiological and biochemical traits of Tepary bean (Phaseolus acutifolius L.) at the Research Station of Islamic Azad University, Arak Branch, Iran. The experiment was performed as a split-plot arranged in a randomized complete block design with three replications. The treatments were two planting patterns (one-row and two-row plantations) and three plant densities (30, 40, and 50 plants per m2). The results showed that that one-row planting pattern and 40 plants per m2 improved seed yield by 75% and 65% compared to 30 and 50 plants per m2 in one-row planting pattern in the second year, respectively. The plant chlorophyll content increased by 20% with two-row plantation and medium plant density compared to high and low plant density in the first year. The highest accumulation of seed carbohydrates (38.26 mg. g-1 FW) was obtained with two-row cultivation and medium plant density in the second year. The relative seed water content significantly decreased with one-row plantation and low plant density compared to a two-row plantation and medium plant density. The least malondialdehyde and proline aggregation (3.2 and 225 µ mol. g-1 FW, respectively) was achieved with two-row plantation and medium plant density. Finally, a two-row planting pattern with medium-density cultivation is recommended to obtain optimal Tepary bean seed yield in the region.