Effect of defoliation and on morphophysiological characteristics under drought stress condition in Sorghum (Sorghum bicolor L.)

In order to investigate effect of drought stress and defoliation on sorghum an experiment were conducted in form of split plot based on randomized complete block design with four replications at field of Islamic Azad University, Varamin branch in 2011. Treatments are include drought stress in three levels (irrigation after 50, 90 and 130 mm evaporation from pan class A) and defoliation in three level (Control, Defoliation 33 and 66). The results showed that drought stress had significant effect on leaf area at floury stage, Biological yield, grain yield, harvest index, lead fresh and dry weight at flowering stage, stem fresh weight at flowering stage, leaf dry weight at floury stage, stem fresh and dry weight atfloury stage, flower dry weight at floury stage, stem length at floury stage, thousand seed weight, panicle length at floury stage,stem diameter, dry weight at physiologic maturity. Defoliation showed significant difference on leaf area at flowering and floury stage, biologic yield, grain yield, harvest index, flower fresh and dry weight at flowering stage, stem dry weight at flowering stage leaf fresh and dry weight at floury stage, stem fresh and dry weight at flowering stage, flower fresh and dry weight at floury stage, thousand seed weight, panicle length at floury stage, stem diameter, dry weight at physiologic maturity. Chlorophyll amount, EC,biological yield, panicle length at flowering and flouring stage under drought stress in contrast to normal irrigation decreased respectively 5, 36, 5, 3 and 3. By increasing in water deficit and Defoliation decreased plant morphologic and physiologic characteristics.