In order to study the effect of drought stress and N fertilizer on material remobilization of wheat cultivars, a field experiment was conducted in 2003-2004 at Islamic Azad University of Shushtar. The design was a factorial in completely randomized block with replications. Treatments were wheat cultivars (Chamran, Showa and Falat), N fertiliser in two levels (50 and 150 kg/ha) and 2 levels of drought stress (without stress, stress at anthesis and stress at grain filling). Chamran and Falat were soft and Showa was durum wheat. Results indicated that The highest and lowest contribution of dry matter remobilization to grain were obtained by Falat (26%) and Shova (6%) cultivars respectively. Nitrogen fertilizer increased dry matter remobilization to grain (17%). Dry matter remobilization to grain with drought stress was 4140 kg/ha and in well irrigation was 4830 kg/ha). Potential of photosynthesis material remobilization from vegetative plant parts and efficiency of mobilization to grain were important characters for stability of grain yield in drought conditions. Therefore, this point can be different for drought stress, breeding cultivars and higth in different regions.

Water Water deficit especially after heading is one of the most effective factors of wheat yield loss in Iran and across the world and identifying the physiological traits related to plant resilience is of great importance in screening for tolerant varieties. The objective of this study was to evaluate the variation in stem reserves accumulation capacity and its relationship with remobilization in some wheat cultivars. 22 wheat cultivars were cultivated in a split plot design with three replications, full irrigation and 40% of field capacity being main plots. The amount of accumulation and remobilization was estimated by measuring internodes weight and stem soluble carbohydrates content (WSC). Significant genotypic variation among cultivars was observed under both normal and drought conditions. Maximum accumulation was found in lower internodes followed by peduncle and penultimate using dry weight measurement method. In WSC measurement method, however, maximum accumulation was observed in penultimate followed by lower internodes and peduncle. Cultivars ranking based on accumulation was also different in two methods. Drought stress caused decline in internodes weight, WSC and yield and remobilization efficiency. The specific stem weight had the highest correlation with remobilization. Significant correlation was found between grain yield and remobilization, specific stem weight and WSC.

Background and Objectives: Wheat is the most important crop on the land, which has always been of particular importance since its domestication and has the highest cultivated area among crops. Among the factors that reduce wheat production in the country, weeds are of particular importance and according to the studies,the average weed damage in wheat fields is 23% in Iran. This study was carried out to investigate the effect of weed control on remobilization, yield and yield components in mixed cropping of wheat cultivars and compare it with monoculture. Materials and Methods: In order to investigate the effect of weed control on remobilization, yield and yield components in mix cropping of wheat cultivars, a randomized complete blocks design with three replications was conducted in research field of Agriculture College and Natural Resources of Darab, Shiraz University during 2018-2019 growing season. Experimental treatments included six levels of weed control at tillering, stem elongation, booting, ear emergence, weed-free and weedy check which in each stage, all weeds controlled manually, and cropping system treatments including of Sirvan monoculture, Setareh monocultures and mix cropping of Sirvan and Setareh, which were in a ratio of one to one. Results: Simple effects of weed control and cropping system on assimilate remobilization, percentage of assimilate contribution, weed biomass, plant height, 1000-grain weight, number of spike per square meter and grain yield was significant. Also, assimilate remobilization, remobilization efficiency and contribution of assimilate in treatment of weed control at tillering stage increased by 37. 7%, 57. 2% and 5. 8%, respectively, compared to weed-free control which these traits in mixed cropping of Sirvan and Setareh increased by 29. 7%, 6. 6% and 18. 2%, compared to monoculture of Sirvan, respectively. Results showed that weed biomass in mix cropping treatment compared to monoculture of Setareh and Sirvan decreased 29. 6% and 21. 25%, respectively. Also, the highest grain yield was obtained in mix cropping, which was 22. 8 and 11. 2% more than Setareh and Sirvan monoculture, respectively. Weed control at tillering reduced grain yield as 11. 9%, which had the lowest yield reduction compared to the other weed control treatments, so it may be the best time to weed control in mix cropping system. Conclusion: The results showed that the mix cropping of wheat cultivars could be successful in weed control and competing, so that the weed biomass in the mix cropping had more reduction and this may be due to more canopy shading on weeds in mix cropping of two wheat cultivars. The results of assimilate remobilization showed that the dwarf cultivar of Setareh had a more efficient in assimilate remobilization and tall cultivar of sirvan by suppress the weeds at flowering has less demand for assimilate remobilization in grain filling stage. Also, the highest grain yield was obtained in mix cropping compared to monoculture and mix cropping can be used as an appropriate strategy for optimizing the use of environmental factors to increase production stability.

Five bread wheat (Triticum aestivum L.) cultivars including Kavir, Pishtaz, Niknejad, Omid and Roshan were evaluated in a split plot experiment based on randomized complete block design with three replications. Water stress and well-watered conditions were assigned to the main plots and varieties to the subplots. Water stress was imposed by withholding irrigation at the booting stage. During a period of 45 days, which spanned before and after anthesis, plants were sampled and changes in dry matter of peduncle and penultimate internodes were assessed. An increase in grain weight was accompanied with a decrease in peduncle and penultimate internodes dry matter, which could be attributed to the remobilization of stored, assimilates to grains. Remobilization of stored assimilates was relatively higher under water-stress condition as compared with the well-watered environment. Under water stress condition, tall cultivars remobilized more assimilate than the dwarf genotypes. In the well-watered plots, remobilization percentage from peduncle was more than penultimate internodes in tall varieties as compared with the dwarf varieties. On the other hand, under water stress condition, more assimilates were remobilized from penultimate than the peduncle in dwarf varieties as compared to the tall genotypes. In the dwarf genotypes assimilate remobilization was reduced under water stress conditions while it was increased in the tall cultivars.

Participatory plant breeding initiated in Iran since 2005 and the present investigation was a part of this program. This investigation conducted in farmer’s field with their participation in cropping season 2010-2011 in Mazhin village of Eyvan region, in Ilam province, west Iran.16 bread wheat were planted as RCBD in four replication. Genotypes were evaluated for Grain yield, remobilization of reserved assimulates to grain, Spike photosynthesis rate, plant height, Days to heading and maturity. For assimilate remobilization rate, the superior genotypes were; Azar2, 13, Rijaw and 8. For spike photosynthesis rate, the superior genotypes were; Azar2, Rijaw, 13, 7& 8. For early growth vigor, Rijaw, 5, Sardari were better than the others. For all of the traits related to drougth, 7 was on of the best genotypes and enhanced good score from farmers, therefore can use in breeding programs in future. For farmer s score Rijaw was the superior genotype. For Grain yield, number 6 was better than checks 24, 41 and 61 percent, respectively. Number 12 enhanced better score from farmers in compare to checks.

Background and Objectives: The shortage of oilseeds and the high volume of oil imports in Iran and the limitation of water resources for the many oilseeds production, showed the necessity of identifying species and varieties adapted to these stressful conditions and determining the most sensitive stages. Nowadays, safflower, due to drought resistance, is considered as a plant crop in the Iranian crop rotation. Therefore, with respect to importance of water stress and selection of appropriate planting date in crop production, this research was conducted to investigate the effect of delay cropping and irrigation regime on assimilate remobilization, yield components and yield safflower. Materials and Methods: In order to investigate the effect of delay cropping and irrigation regime on assimilate remobilization rate, yield components and yield of safflower, a field experiment was conducted as split factorial in a completely randomized blocks design with three replicates at Agriculture College and Natural Resources of Darab, Shiraz University, during 2018-2019 growing season. Experimental factors consisted of irrigation regimes in three levels included normal irrigation, Cutting of irrigation at flowering and cutting of irrigation at seed filling, three planting dates (6 December, 26 December and 15 January) and two safflower cultivars (Goldasht and local Isfahan). In this research, dry matter remobilization, remobilization contribution and remobilization efficiency, yield components and yield of safflower were determined. Results: Results showed that the measured traits were affected by irrigation regime, planting date and cultivar, significantly. Cutting of irrigation at flowering reduced number of capitule per plant, number of seeds per capitule, 1000-seed weight and grain yield of safflower cultivars by 21. 86%, 23. 87%, 28. 37% and 33. 74%, respectively compared to normal irrigation. The amount of dry matter remobilization, remobilization contribution and remobilization efficiency in cutting of irrigation at flowering increased 30. 44%, 37. 81% and 25. 37%, respectively compared to normal irrigation. Also, delayed third planting date (15 January) reduced dry matter remobilization (44. 17%), remobilization contribution (22. 72%), remobilization efficiency (17. 88%), number of capitule per plant (%). 14. 57, number of seeds per capitule (20. 65%) and grain yield (13. 31%). Conclusion: Cutting of irrigation at flowering and seed filling treatments decreased 52. 32% and 34. 54% of grain yield in Isfahan local cultivar at second planting date (26 December) compared to the normal irrigation treatment, respectively. However, seed yield in this treatment did not differ significantly with the treatment of cutting of irrigation at seed filling in planting date on 6 December in Isfahan and Goldasht cultivars which seems to be due to increased assimilate remobilization and remobilization efficiency in cutting of irrigation at seed filling compared to normal irrigation. Therefore, selection of optimum planting date (26 December) compared to early planting date (6 December) and early mature Goldasht cultivar by 12. 91% higher yield can be an appropriate strategy to improve and increase safflower seed yield under late season water stress in semi-arid regions.

In order to investigate the effect of types of mulch and sowing depth on partitioning and remobilization of assimilates in chickpea ILC481 cultivar, this experiment was carried out as split plot based on randomized complete block designs with three replications at research farm of Campus of Agriculture and Natural Resources, Razi University of Kermanshah in 2011-2012 cropping year. Main plot were mulch treatments including control treatment, corn stubble mulch, wheat stubble mulch, farmyard manure mulch, soil mulch (using sweep) and supplementary irrigation (one irrigation in order to investigate the effect of types of mulch as well as comparison to the ideal conditions) and sub plot was planting depth (4, 8 and 12 cm). The results of experiment showed that there was significant difference between different sowing depth and mulch treatments regarding to amount of grain yield and number of grain per square meter at main stem. Grain yield at main stem of wheat stubble mulch, soil mulch, corn stubble, farmyard manure and supplementary irrigation increased 43, 24, 23, 22 and 218 percent compared to the control (without mulch), respectively. There was significant difference between different sowing depths regarding to the portion of stem remobilization in yield and the efficiency of stem in the dry matter transition to the grain. The portion of stem efficiency at dry matter transition to the grain in 4, 8 and 12 cm sowing depth was 11.38, 8.2 and 5.11 percent, respectively. In general, the efficiency of remobilization assimilates of stem to grain and the role of remobilization in yield reduced by increasing the sowing depth and using the mulching treatments.

The object of this study was the assessment of assimilate remobilization (AR) in different bread wheat (Triticum aestivum L.) genotypes under rainfed (Rf) and supplemental irrigation conditions (SupIr). For this purpose, 44 winter wheat genotypes were evaluated in a lattice design arrangement (7×7) with two replications in both conditions during the 2018-2020 cropping seasons in the Dryland Agricultural Research Institute (DARI), Maragheh Iran. Results indicated significant year × genotypes interaction effects among the genotypes for grain yield (GY), current photosynthesis rate (CPhR) and photosynthesis efficiency (PhE), AR and assimilate remobilization efficiency (ARE), and AR contribution (P < 0.01). In the first year, maximum GY belonged to genotype 4 (2462 kg ha-1) and genotype 33 (4234 kg ha-1) in Rf, and SupIr conditions, respectively. For CPhR, genotypes 33 (439.05 mg plant-1) and 26 (196.300 mg plant-1) indicated the maximum value in the SupIr, and Rf conditions, respectively. For PhE, genotypes 33 (42.950 mg plant-1), and 21 (17.950 gr gr-1) showed the highest value in the SupIr, and Rf conditions, respectively. Genotypes indicated significant differences in AR contribution (P < 0.01). The highest value for AR contribution (248.200 mg plant-1) was observed for genotype 8 in SupIr, and genotype 4 (201.60 mg plant-1) in Rf conditions. For ARE, genotypes 4 and 8 indicated the maximum value and for AR contribution, genotypes 12 and 8 showed the highest value under the Rf, and SupIr conditions, respectively

Background and Objectives: Wheat is one of the major plants cultivated in arid and semi-arid regions and is number one with respect to planting area and production in the world. Sensitivity of wheat to water stress in not equal in all of the growth stages and flowering stage is very sensitive to water stress, which silicon application could be able to increase the tolerance of wheat to water stress. This research was conducted to investigate the effect of silicon spraying on assimilate remobilization and grain yield of wheat under late season water stress condition. Materials and Methods: In order to investigate the effect of silicon on remobilization and yield of two bread and durum wheat cultivars, under late season water stress, a field experiment was conducted as split factorial experiment in a completely randomized blocks design with three replications at Faculty of Agriculture and Natural Resources of Darab, Shiraz University, Darab, Shiraz University, during 2017-2018 growing season. Experimental treatments consisted of water stress in two levels included normal irrigation and water stress at the end of flowering, silicon (Si) spraying at 0, 1, 2, and 3 mM and two wheat cultivars (Chamran and Shabrang). In this research, dry matter remobilization, remobilization contribution and remobilization efficiency were determined. Results: The results showed that the main effects of water stress, cultivars and silicon had significant effects on dry matter remobilization, contribution efficiency, remobilization efficiency, number of seeds per spike, 1000-grain weight, harvest index, biological yield and grain yield. Foliar application of 3 mM Si increased 12. 7%, 25. 3% and 16% of dry matter remobilization, contribution efficiency, and remobilization efficiency of wheat compared to no Si application, respectively. Also, in the 3 mM silicone under water stress, the number of seeds per spike and 1000-grain weight increased 43 and 13%, respectively. In normal irrigation condition, grain yield had a positive and significant correlation with 1000-grain weight (r = 0. 545**), while in water stress conditions, grain yield was had a positive and significant correlation with 1000-kernel weight (0. 520**), harvest index (0. 404*), biological yield (0. 810**) and contribution efficiency (0. 459**). Conclusion: The foliar application of 3mM Si improved dry matter remobilization and remobilization efficiency by 67. 2 and 38. 7% in Chamran cultivar, respectively, which resulted in 19. 7% increase in grain yield of Chamran cultivar compared to Shabrang when plant exposed to water stress. Overall, foliar application of 3 mM silicon could be a suitable approach in improve and increase the wheat grain yield under late season water stress in semi-arid areas.

Hormones play an important role in grain filling regulation (as a reproductive sinks) and the demand for assimilates from current photosynthesis and remobilization sources as well. The objective of this study was to improve sink strength through GA3 application, measuring remobilization and yield under terminal drought stress. Twenty wheat cultivars were cultivated in a split split plot arrangement based on RCBD design with three replications, full irrigation and 40% of field capacity being main plots, GA3 foliar application (60 μM) and control (No GA3) were regarded as sub-plots and wheat cultivars were sub-sub-plots. Grain yield, biological yield, yield components and remobilization (by internodes) were estimated. Significant variation among cultivars was observed under both full irrigation and stress treatments. However, the response of the cultivars to the gibberellin application was almost the same. Drought stress reduced grain yield (33%), biological yield (20%), 1000-seed weight (14%), number of grains per spike (14%) and remobilization (8%), but application of gibberellin increased these traits under both conditions. Gibberellin foliar application at the wheat pollination stage had a positive effect on sink strength and remobilization, especially under full irrigation conditions. Under drought stress conditions, the positive effect of gibberellin application on the studied traits was less due to the reduction of grain filling period. Based on the results of present experiment, foliar application of gibberellin is not recommended under drought stress conditions.