Effects of nitrogen fertilizer and irrigation regimes on seed yield of calendula (Calendula officinalis L.)

Abstract

This research was conducted in experimental field of Islamic Azad University of Takestan branch in Iran during 2006. The experimental unit was designed by achieved treatment in factorial on the basis of completely randomized block design with four replicates. The nitrogen was applied to the main plots at the rate of non-application, 30, 60 and 90 kg N ha^-1 and the irrigation after 40, 80 and 120 mm water evaporation from evaporation pan assigned factorially to the subplots. The results showed that irrigation had a significant effect on seed yield, thousand seed weight, head diameter and number of seeds per head (P 0.01) such that maximum head diameter (25.67 mm), number of seeds per head (31 seed/head), thousand seed weight (15.18 g) and seed yield (3044 kg ha^-1) were achieved under irrigation after 40 mm evaporation. Nitrogen had a significant effect on all plant characteristics (P 0.01) and highest thousand seed weight (12.66 g), seed yield (1998 kg ha^-1), head diameter (23.96 mm) and number of seeds per head (29.25 seed/head) achieved after application of 90 kg N ha^-1. The results of this experiment showed that nitrogen increased the seed yield and delay of irrigation reduced seed yield of calendula significantly.