effect of polyethylene and organic mulches in different intervals of irrigation on morphological characteristics and grain yield of sunflower (helianthus annus l.)

in order to investigate the effects of polyethylene and organic mulches in different irrigation intervals on morphological characteristics and seed grain of sunflower (helianthus annus l.) hybrid azrgol, an experiment was conducted in split-plot design based on randomized complete blocks with three replications at research farm of college of aboureihan, university of tehran during year of 2009. main factor was three irrigation interval including of 7, 12 and 17 days and sub-factors were treatments without mulch as control and different types of mulch (polyethylene, cow manure including of 8.5 t.ha-1,17 t.ha-1, 25 t.ha-1, wheat stubble mulch in three levels of 2.5, 5.5 and 7.5 t.ha-1). plant height, head diameter, seed number in each head, 1000-seed weight, seed yield, oil yield, harvest index were investigated. the results indicated that the effect of irrigation period and the effect of mulches for all measured traits were significant. highest seed yield with average of 2.965 t.ha-1 was obtained from 7 days irrigation and also polyethylene mulch and stubble mulch level three in different irrigation periods, had the highest yield. the overall results showed that, using mulches by reducing irrigation water use can increases the quality and quantity seed yield. regarding the results of the study and non-toxic effects of stubble mulches in agriculture, we suggest their usage.