Study on the effect of seed size on agronomic characteristics, grain yield and drought tolerance of chickpea

Seed size has been known role as one of the important and effective traits on yield, growth and development in many field crops. In order to study the effect of chickpea genotypes seed size on drought tolerance an experiment carried out as split-split plots based on randomized complete blocks design during three cropping seasons (2010-2013). Drought stress levels as main plots were one time irrigation at planting, two and three times (each one after one month from planting date) and four chickpea genotypes ("Arman", "Azad", "ILC 482" and a "landrace from Turkey") were in sub plots and three seed sizes (large seeds with > 8 mm, medium seeds with 6-8 mm and small seeds with less than 6 mm in diameters) were in sub plots. Date to flowering and maturity, grain filling period, growth vigor (in start of flowering and maturity stages), plant height, one hundred seeds weight, dry biomass and grain yields were noted and analyzed. Drought tolerances of seed sizes and genotypes evaluated by using of different stress tolerance indices (Stress Susceptibility Index, Stress Tolerance Index, Tolerance Index, Mean Productivity Index and Geometric Mean Productivity Index) and based on grain yields and with using from traits ranking method. Results showed that the highest grain yields belonged to medium and large seed sizes (900 kg ha-1). In conclusion and based on drought tolerance indices and traits ranking method, "Azad" cultivar was tolerated to drought stress. The small and large seeds were susceptible and tolerated to drought stress, respectively.