evaluation of yield and yield components of black cumin (nigella sativa l.) under different plant density and limited irrigation condition

research on crop response to deficit irrigation is important to reduce agriculture water use in areas where water is limited resource. using drought resistant landraces with irrigation scheduling based on phenological stages in semi-arid and arid regions may provide an opportunity to optimize irrigation efficiency and water savings in these regions. in order to evaluate of yield and yield components of black cumin under different plant density and limited irrigation condition an experiment was conducted in research farm of islamic azad university of damghan during growing season of 2007-2008. the experimental treatments were arranged in split plots based on a complete randomized block design with three replications. the limited irrigation (based on phenological stages) treatments were included: cutting irrigation at blooming (folded flowers), cutting irrigation at flowering stage, cutting irrigation at seed formation and normal weekly irrigation (control) were allocated to the main plots and different plant density: 100, 150, 200 and 250 plant per square meter (m2) were allocated to sub plots. the results showed that the effect of limited irrigation, plant density and their interaction on plant height, number of follicle, follicle weight, number of seed, 1000 seed weight, seed yield, biological yield and harvest index black cumin. the highest yield and yield components was obtained in normal irrigation (control) and 200 plant density and the lowest yield were obtained when irrigation cut at the blooming stage and 250 plant density. there was a significant correlation between seed yield and number (r=0.90), 1000 seed weight (r=0.95) and biological yield (r=0.97). optimum plant density of black cumin was decreased under limited irrigation treatments. under normal (control) and limited irrigation, optimum plant density was 200 and 150 plant per (m2) respectively.