the effect of drought stress and different rates of animal manure with super absorbent polymer on grain yield and yield components of corn (zea mays l.)

to investigate the effects of drought stress and different combinations of animal manure with super absorbent polymer on yield and yield components of corn, a split plots design was conducted based on a randomized complete block design with 3 replications in fars agricultural research center in 2007. irrigation treatments were assigned as the main factor in three levels: 70, 105 and 140 mm evaporation from pan class a. different combinations of animal manure and super absorbent polymer application were assigned to the sub plots in six levels, namely, s1: control, s2: 100% animal manure (40 t/ha), s3: 100% super absorbent polymer (200 kg/ha), s4: 50% animal manure + 50% super absorbent polymer, s5: 35% animal manure + 65% super absorbent polymer, and s6: 65% animal manure + 35% super absorbent polymer. the results showed that, kernel number per ear, 1000 grain weight, grain yield and biological yield decreased by drought stress and increased with animal manure and super absorbent polymer application. higher levels of drought stress decreased the grain yield. the maximum yield (12.43 t/ha) was detected in control irrigation. yield and yield components were significantly increased by using of both animal manure and super absorbent polymer compared to other treatments. the results showed that, the combinations of animal manure and super absorbent polymer application (s6 treatment), significantly increased the grain and biological yield by 15.97 and 8.95 percent compared to control, respectively.