Investigation of the effects of planting date and cultivar on physiological traits and grain yield of irrigated wheat (Triticum aestivum L.) in Khorramabad climate

Despite genetic advances, the emergence of limiting factors such as climate, soil and crop management has led to a significant gap in many areas between farmers harvest performance and genetic yield potential. Knowing the limiting factors and proper planning and determining strategies to increase the adaptation of crops to these possible changes, causes the appropriate response of crops to these changes. For this purpose, the present study was conducted to investigate the effect of planting date and cultivar on yield and experimental physiological traits as a split plot in the form of a randomized complete block design with three replications in the crop year 2020-2021 in the Faculty of Agriculture, Lorestan University. The main factor included the four planting dates of 6 October, 21 October, 5 November, 20 November and the secondary factor of the cultivar, which included Chamran 2, Sirvan and Mihan. The results of analysis of variance showed that the simple effect of planting date on all studied traits was significant at one percent probability level and the simple effects of cultivar on photosynthesis rate, grain yield at one percent probability level and mesophilic conductance, stomatal conductance at five percent probability level were significant. Planting date was 6 October due to early sowing and occurrence of growth stages with temperatures lower than plant tolerance and planting date was 20 November due to delay in sowing time reduced seed yield. In general, the appropriate planting date, while increasing the optimal conditions for wheat cultivars, the growth and physiological characteristics of the plant, including photosynthetic components, provide favorable conditions for better plant growth and ultimately increase grain yield. In this study, this planting date of 5 November and Mihan cultivar is recommended as the best planting date and cultivar for Khorramabad region and similar climatic regions, respectively.