اثر رژیم های آبیاری بر ویژگی ‌های مورفوفیزیولوژیکی و عملکرد هیبرید‌های ذرت علوفه ای

In order to investigate the effect of drought tension on some traits and yield of a number of new forage corn hybrids, this experiment was conducted as split-plots in statistically randomized complete blocks design with three replications at the experimental field of seed and plant improvement research institute of karaj in 2009. in the main plots three levels of normal irrigation, mild tension and sever tension (irrigation after 70, 100 and 130 mm accumulative evaporation from evaporation pan class a, respectively) and in sub-plots 14 corn hybrids was compared. the amount of consumed water was controlled by using power control placed at the beginning of the main faucet. the results showed that hybrids difference in terms of plant height and dry forage yield was significant at five percent probability level and in terms of leaf number, leaf area index and ear dry weight was significant at one percent probability level, while no significant difference between leaf dry weights of hybrids was observed. also, all the investigated traits except the number of leaf in plant react to drought tension and their difference in different tensions was significant at one percent probability level. the interaction irrigation regimes and hybrid was not significant for any one of the traits that indicates the same reaction of the studied hybrids towards applied irrigation regimes conditions. switching the irrigation cycle from normal irrigation treatment to sever tension decreased dry forage yield by 44 percent .hybrid number 4 (ksc700) in terms of more weight of dry ear (771/54 gram) and with dry forage yield (15565 kilogram per hectare) in drought tension conditions was the best hybrid in which the high yield in this hybrid can be due to its longer growth period as provides more time to produce and accumulate materials for plants. with respect to correlation one can conclude that traits plant height, number of leaf, leaf area index, leaf dry weight, shoot dry weight and ear dry weight in forage yield changes in the shortage conditions of soil moisture can have a significant impact.