In order to identify the correlations and relationships between different traits in the bread wheat, 30 genotypes were investigated as sub-factors under the split plot experiment in the completely randomized design in greenhouse and the randomized complete block design in the field with three replications under the normal irrigation and post-anthesis water stress conditions. The results of the canonical correlation analysis showed that at both normal and moisture stress levels, there was a significant correlation between the pair of canonical variables obtained from the phenological traits and the yield components. Under the normal conditions in the greenhouse, to increase the spike density and length, the number of days to 50% flowering can be considered as a suitable selection criterion. According to the results of canonical correlation analysis, under the stressed conditions in greenhouse, to increase the spike length, the number of days to the heading, maturity and 50% of flowering were among the important and effective factors. Under the optimum irrigation conditions in the field, the number of days to maturity was considered as one of the factors influencing the seed weight per spike. The results of canonical correlation analysis under the field stress conditions showed that to increase the 1000-seed weight, the number of days to maturity can be considered an appropriate selection criterion.

This study was conducted during summer and winter of 2018- 2019 in the agricultural research field of Shahid Chamran University. Experimental design was split- plot based on RCBD with three replications. The main plot was the type of agricultural system in three levels including conventional (Conv), organic (Org) and sustainable (Sust) (integrated between Conv and Org) and sup- plot was the type of pre- cultivated crop in sequence with wheat including cultivation of mung bean (M- W), corn (C- W), sesame (S- W) and fallow (F- W). Yield quantity (yield and its component) and quality (grain protein), an estimate of photosynthesis matter transfer index of wheat and soil organic carbon (SOC) after one double-cropping were measured. The result showed that the highest (545.04 g/m2) and the lowest (409.28 g/m2) seed yields were obtained in Conv and Org respectively. In contract, with the changing type of system from Conv to Org, grain protein was increased significantly (from 8.3 to 9.6 %). In addition, the highest (535.47 g/m2) yield of wheat was obtained from M- W double cropping. On the other hands the highest remobilization and current photosynthesis matter were obtained in the organic agricultural system with M- W and conventional with M- W double cropping. The situation of SOC showed that the highest (33.18 mg/g) SOC was obtained in the organic agricultural system with C- W double cropping. The reason for improving SOC in the organic and sustainable agricultural system was application of organic matter (compost and vermicompost) and crop residue management. Totally, from the crop ecology point of view, sustainable agricultural method with a sequence of M- W was the most desirable system.

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.

One of the ways to increase wheat yield is using new cultivars. In this evaluation, an experiment was conducted in a randomized complete block design with three replications in Saqhez in Kurdistan province at 2017-2018. New cultivars included Homa, Baran, Ohadi, Hashtrood, Azar 2 and cross Azar 2 (Dari 1), which were compared with Sardari variety. The results showed that Baran cultivar had the highest grain yield (2793 kg/ha) and Sardari cultivar had the lowest grain yield (803 kg/ ha). Maximum (37. 33 g) and minimum (32. 62 g) of 1000 seed weight belonged to Homa and Sardari cultivars, respectively. The highest plant height (121. 7 cm) belonged to Cross Azar cultivar (Dari 1) and the lowest plant height (96. 67 cm) belonged to Sardari cultivar. Although there was no statistically significant difference between cultivars in terms of seed number per spike, but Hashtrood cultivar had the highest value (27) of it and Ohadi cultivar had the lowest value (23) of it. Also, Maximum spike number per m2 belonged to Hashtrood cultivar.

In order to study the growth rate, yield and yield components of four wheat cultivars under rainted conditions and two irrigation regimes (I-at planting time and ear emergence, 2-planting time, ear emergence and grain filling), a factorial experiment on the basis of randomized complete blocks design with three replicates was conducted in Dryland Agriculture Research Institute at Maragheh during growing season of 1997-98. In this experiment wheat cultivars of Sabalan/1-27-56-4, Anza/3/Pi/Nor//Hys/4/sefid, 4493-P.1533-Bez and Sabalan were used. Several traits such as crop growth rate, relative growth rate, dry matter accumulation Per unit area, number of ears per unit area, number of grains per ear, 1000 grain weight, biological yield, grain yield, harvest index and productivity degree were determined. The results showed that drought stress led to the reduction of dry matter production, crop growth rate and relative growth. rate. There were no significant differences between wheat cultivars, regarding green cover percentages, crop growth rate and relative growth rate. All traits (except grains per ear and harvest index) were affected by water deficit. However, irrigationx variety interaction was not significant for any trait. Considering traits studied in this research, no significant differences were found between two and three times of irrigation. Green cover percentage, plant height, crop growth rate, biological yield and productivity degree were significantly correlated with grain yield. Among these traits, mean green cover had the highest positive correlation with grain yield. Since this index could be determined easily and rapidly, it can be recommended as a suitable index for evaluating field performance of different crops.

One of the main problems in crop production in Iran is the difference between actual yield and attainable yield which is called yield gap. Thus, identifying yield constraints and yield gap are important. To do this, a study was conducted in 95 farms Gorgan of in five villages, during two years 2007 and 2008. In this study, all of the information about management operations, soil and crop characteristics were recorded and measured (including 200 variables). Then, relationships between variables and yield were considered (using stepwise regression). The results showed there is a 2348 kg/ha difference (gap) between actual yield (average farmers' yield) and attainable yield (maximum farmers' yield). It was identified that rate of potassium fertilizer before planting, rate of nitrogen fertilizer after planting, leaf area index at anthesis, leaf chlorophyll index at anthesis, total nitrogen uptake at maturity and the length of vegetative growth period were responsible in creation of yield gap with contribution of about 20, 18, 19, 10, 14 and 19%, respectively. Data investigations revealed that leaf area index at anthesis, leaf chlorophyll index at anthesis and total nitrogen uptake at maturity were controlled by nitrogen fertilizer management. Also, the length of vegetative growth period was controlled by planting date. Thus, it was then concluded that rate of applied potassium, nnitrogen nutrition management and planting date are the most important responsible factors in creating yield gap with contribution of about 20, 61 and 19%, respectively. Optimizing of these factors could be increase wheat yield in Gorgan up to 2348 kg/ha.

Background and objectives: Given the increasing demand for food supply due to human population growth and the limited arable land, the role of plant breeding in increasing crop production is evident. Wheat (Triticum spp. ) is known as an important food source in the world because of its adaptation to different environments. Triticale (X. Triticosecale Witmack) has high adaptability to biotic and abiotic stresses and is able to produce efficiently even in poorly fertilized soils and low input farming systems. Heterosis is a natural phenomenon that depends on the species and genetic variation and is called the increase in hybrid vigor of parents, which can be explored to increase crop production. Since the exploitation of heterosis is promising in wheat, the employment of putative hybrids for sustainable food supply has potentially increased. Hence, the aim of this study was to estimate heterosis and to evaluate the coefficients of phenotypic and genetic variation as well as heritability estimates. Materials and methods: A total of 79 genotypes including 19 common wheat, 3 durum wheat, 4 triticale along with their 53 F1 hybrids were used, in this study. Morphological traits including yield and yield components viz. plant height, number of spike per plant, number of grains per spike, grain weight per spike, 1000 grain weight and grain yield per plant were measured. The heterosis estimates in the studied hybrids were calculated based on the mid-parent and better-parent. After analysis of variance, coefficients of phenotypic variation, coefficients of genetic variation and general heritability were estimated. Results: The results of analysis of variance showed significant differences among the genotypes for the studied traits. Mean squares of parents versus hybrids were significant for all traits, indicating heterosis in the studied traits. F1 hybrid derived from Long Spike 2 × Sirvan cross had the lowest heterosis compared to the mid-parent and superior parent for plant height. The highest percentage of heterosis for grain yield per plant belonged to the hybrid derived from the cross between Long spike 5 × Roshan. The estimated heterosis for grain yield based on mid-parent value showed a range of 25. 34 to – 25. 41, indicating the high genetic diversity of the parents used to produce the 53 F1 hybrids studied. Conclusion: Given the genetic diversity observed in this study indicating heterosis in the studied traits as well as high heritability in the traits, the diversity can be explored either by hybrid breeding strategy or advancing segregating generations toward developing new cultivars.

In order to investigate the possibility of quinoa producing in Garmsar, Iran, a factorial experiment conducted in randomized complete block design with three replications in 2018-2019 growing season at Garmsar Agricultural Research Station. The factors were planting date at three levels (March 6th, April 1st and April 6th) and the three genotypes of quinoa (Q26, Q29 and Titicaca). Results showed that the effect of planting date was significant for all studied traits except the harvest index. Also, all studied traits were significantly different in all genotypes. Titicaca planted on March 6th had the highest yield (2276 kg.ha-1).The grain yield and yield components decreased with the delaying the planting date. Compared to early plantings, Latest date, April 6th, led to reduction of all traits, especially grain yield (about 50%). The results of simple phenotypic correlation between the studied traits showed that grain yield per hectare had the highest correlation with plant yield (0.877) and then with leaf area index (0.832), panicle weight (0.815) and number of branches per plant (0.745) that was significant at the 1% probability level.

A robust crop model can assist in genetic improvement and cultural management of the crop. The objectives of this study were to describe a wheat (Triticum aestivum L.) model and to report results of its evaluation. The model simulates phenological development, leaf development and senescence, crop mass production and partitioning, plant nitrogen balance, yield formation and soil water and nitrogen balances. The model includes responses of crop processes to environmental factors of solar radiation, temperature and nitrogen and water availability. Parameters are inputted in describing physiological processes so that these can be varied to define genotypic differences. The model uses a daily time step and readily available weather and soil information. The model was tested using independent data and indicated an acceptable performance for important crop attributes as compared to observed results including days to anthesis (CV=4.5%; r=0.98) and maturity (CV=5.6%; r=0.96), crop LAI (CV=11.8%; r=0.80) and dry mass at anthesis (CV=9.3%; r=0.72) and total crop mass (CV=9.5%; r=0.82) at maturity and grain yield (CV=8.4%; r=0.89). It was concluded that the model can be used in simulation studies of wheat yield and its limitations in response to environmental conditions, management inputs and genetic factors.

In order to determine the effects of optimal fertilizer application on wheat yield quantity and quality relative to farm reference values, this study was conducted in 2016-17 as a research-extension pilot over a control plot of 5000 m2 and an equal plot of optimal nutrition treatment on four farm fields in the four provinces of Khuzestan, Fars, Sistan, and Golestan. Prior to wheat cultivation, soil samples from a depth of 0-30 cm were taken from each field using the combined sampling method and fertilizers were applied on the treatment plots based on soil test results. Other farm operations (including tillage, irrigation, cultivation, and cultivar selection as well as pest, disease, and weed control) were carried out following local farmer practices. Using the quadrant sampling method, three samples were taken from each wheat plot in each region (both treatment and control) to measure such traits as plant height, number of grains per panicle, panicle length, weight of one thousand seeds, biological yield, and grain yield. It was found that optimal nutrition of wheat cultivations based on soil test results had positive effects on panicle length, biological yield, and grain yield but no significant effects on other traits. Specifically, grain yield in experimental treatments across the four provinces showed a significant mean increase of 21. 3% relative to those measured in farms under local farmer practices. It may be concluded that combined application of basic fertilizers, biofertilizers, and growth stimulants in accordance with diets based on soil test results should be practiced in the study regions if reduced use of chemical fertilizers, improved cost-effectiveness, and increased wheat grain yield are sought.