Abstract

The aim of this study was to investigate the effects of terminating irrigation at different developmental stages and Azospirillum inoculation on quantitative yield of black cumin (Nigella sativa L.). The experiment was conducted during the growing season of 2011 at the Experimental Station of the Research Institute of Forest and Rangeland, Damavand, Iran. Treatments consisted of irrigation with three levels (W₁ = normal irrigation from emergence to harvest (control), W₂ = irrigation terminated at the start of budding and W₃ = irrigation terminated at the start of flowering) and Azospirillum inoculation at four levels (A₁ = non-inoculated, A₂ = seed inoculated and A₃ = spraying on the plant base at stem elongation stage, A₄ = seed inoculated + spraying on the plant base at stem elongation stage). The present results have shown that irrigation terminated at the start of budding caused significant reduction in number of follicles per plant, biomass production and seed yield.Azospirillum had positive effects in all measured traits, especially when it used at two times (at seed inoculated + spraying on the plant base at stem elongation stage or A₄ treatment).

Key words: Irrigation, Nigella sativa, yield, biofertilizer.