physiological characteristics of chickpea (cicer arietinum l.) cultivars under drought stress and nitrogen fertilizer as starter

drought stress is the most important factor that reduces yield in crops including chickpea and causes some changes in seed composition. this study was performed in order to evaluate the effects of drought stress and starter nitrogen fertilizer on four cultivars of chickpea. experiment was performed in a split-factorial using randomized complete block design with three replications. drought stress treatment stand as main plots in three levels consist of no drought stress (complete irrigation), moderate drought stress (irrigation at planting and early flowering) and severe drought stress (no irrigation). nitrogen fertilizer in two levels (0 and 25kg n/ha) and cultivar treatment (four cultivars azad, bivanij, hashem and ilc482) allocated in sub plots. the results showed that effects of drought stress treatments were significant on proline content, amount of soluble sugar, membrane stability index (msi), relative water content (rwc), chlorophyll-a, chlorophyll-b, total chlorophyll and excised-leaf water loss (rwl). application of nitrogen fertilizer treatment only significantly increased membrane stability index (msi). effect of cultivar treatment was significant on proline, soluble sugar, membrane stability index (msi), chlorophyll-a, total chlorophyll, relative water content (rwc) and excised-leaf water loss (rwl). results showed that with increase of drought stress level amounts of chlorophyll-a, chlorophyll-b, total chlorophyll, relative water content (rwc) and membrane stability index (msi) decreased while proline content and soluble sugar increased by three and two-fold compared to control, respectively. this osmoprotectant accumulation probably explains increase in plant tolerance to drought stress.