Study On Agronomic Traits For Increasing Grain Yield Of Wheat In Cold Dryland Areas

In order to study the effects of agronomic traits on grain yield of wheat and determine the best criteria for selection of high yielding and adaptable genotypes in cold dryland areas, 385 advanced wheat genotypes were evaluated in Dryland Agricultural Research Institute (DARI) at Maragheh in 1997-98 cropping season. Nine experiments, each with 24 lines in RCBD with four replications and one preliminary yield trial in simple lattice design with two replications were conducted. Results showed highly significant differences for grain yield, days to heading, days to maturity, plant height and 1000 kernel weight among the lines. The classification of genotypes for days to heading indicated that the highest grain yield was obtained from the early heading group with average grain yield of 1790 k ha-1, and the lowest grain yield was harvested from the very late heading group with 710 k ha-1. The classification of genotypes for plant height indicated that tall and early heading genotypes produced higher yield than the short and late heading genotypes in rainfed areas. The results also showed that correlation coefficient between days to heading and plant height was negative and significant (r=-0.30*) in the late heading groups. In early heading group, plant height had positive and highly significant correlation (r=0.57**) with grain yield which indicated the importance of selection for earliness and tallness in dryland areas. Meanwhile, high and low 1000 kernel weight were obtained from early and late heading group, respectively. The classification of genotypes for growth habit, indicated that winter types had higher yield, higher plant height, higher 1000 kernel weight, and also had more tolerance to cold than facultative and spring types. Overall, the results of this study revealed that, the selection of earliness, winter type and high plant height could increase grain yield in wheat improvement program in cold dryland areas.