Effect of irrigation regimes on yield and quality of forage maize (KSC 704) in Rasht region in Iran

To investigate the effect of deficit irrigation on dry forage yield, protein and fiber content of maize (KSC 704), a field experiment was conducted using complete randomized block design with four treatments and three replications in 2007 and 2008 at research farm of faculty of agricultural science of University of Guilan in Rasht,Iran. The experimental treatments included; 50% (I3) full irrigation as the control, 75% (2) and 100% (I1) of Total Available Water (TAW) depletion, and non-irrigated (I0) or rainfed conditions. Results of combined analysis of variance showed that irrigation regime significantly affected the dry forage yield, total protein content and irrigation water productivity index (P<0.01) and stem dry weight proportio (P<0.05). Mean comparison showed that dry forage yield, ear dry weight proportion (%) and total protein content increased by decreasing irrigation, however, I3 and I2 were not significantly different. The mean dry forage yield and total protein content of I3, I2, 100%I1 and I0 treatments were 15984.4, 14948.9, 12165.3 and 10418.4 kg.ha-1 and 5.0%, 4.7%, 5.3% and 6.0%, respectively. The water productivity index also differed in different irrigation regimes, and the highest water productivity index (9.4 kg.m-3) was observed I1 and the lowest 3.7 kg.m-3) in I3. Considering the results of this experiment, it can be concluded that application of 75% (2) of total available water depletion will be adequate for producing dry forage of maize with desirable quality in Rasht region in Iran.