The effect of water deficit stress and nitrogen fertilizer on yield and water use effeciency of Calendula officinalis L

In order to study the effect of water deficit stress and different nitrogen levels on seed yield, yield components and water use effeciency of Calendula officinalis L., an experiment was conducted as split plot design based on randomized complete blocks with three replications, at research field of Islamic Azad University of Birjand branch in 2009. In this research water deficit stress set as main factor with three levels (irrigation after 60, 120 and 180 mm evaporation from pan class A) and nitrogen set as sub factor with four levels (0, 60, 120 and 180 kg N ha-1). The results showed irrigation trearments had significant effect (α=1%) on seed yield and it,s components, biological yield, harvest index and water use efficiency for seed and biomass. With incereasing of irrigation intervals from 60 to 180 mm evaporation from pan class A, seed number per capitul, number of capitul per m2, 1000-seed weight, seed yield, number and dry yield of flower decereased 26.6, 49.5, 39.6, 79.3, 65.6 and 72 percent, respectively. The highest biomass yield and weight of one capitul was releated to irrigation after 60 mm evaporation treatment, but irrigation after 60 mm evaporation treatment had the highest WUE. Also the results showed that nitrogen fertilizer trearment affected significantly (α=1%) all traits except capitul number per m2 nitrogen fertilizer application increased these traits, significantly. Interaction of irrigation and nitrogen on all traits was not significant. In conclusion, irrigation after 120 mm evaporation with 120 kg N ha-1 had suitable seed yield with the highest WUE for seed.