Effect of plant density on some growth and physiological responses, and antioxidant enzymes activities of chickpea (Cicer arietinum L.) under different irrigation levels

In order to investigate the effect of different levels of plant density and irrigation on some morphologic and physiologic responses and antioxidants activities in chickpea cv. Hashem, an experiment was conducted at Goonbad-e-Kavoos region during 2012-2013 cropping season. Treatments were arranged as split plot in randomized complete block design with four replications. Different irrigation regime levels (rainfed without irrigation, irrigation at flowering stage, and irrigation during pod filling stage) were assigned to main plots and sub-plots comprised of different plant densities (20, 30, 50, and 70 plants/m2). Results showed that different irrigation regimes significantly affected traits except for days to 50% flowering and plant height but plant density factor had significant impacts only on days to 50% flowering, plant height, days to physiologic maturity, seed yield, biologic yield, and leaf chlorophyll index. Results showed that irrigation caused significant increase in leaf relative water content and leaf chlorophyll index while it decreased grain protein content, superoxide dismutase and catalase activities. Maximum and minimum grain protein contents were produced in no-irrigation and irrigation during pod filling stage, respectively. Meanwhile, the maximum and minimum grain yield was gained by irrigation at flowering stage and rainfed without irrigation, respectively. Under plant density levels, the maximum and minimum grain yield was produced in 70 plants/m2 and 20 plants/m2, respectively. Irrigation at flowering stage × 70 plants/m2 had the highest grain yield among all treatments of the study.