Effect of drought stress and application of clinoptilolite on yield and quality of silage corn hybrids

Present study was carried out to evaluate the effects of drought stress and clinoptilolite on the yield and forage quality of silage corn hybrids. The experiment was arranged in a three-replicated split-spilt plot based on randomized complete blocks design (RCBD) with three irrigation regimes including optimum irrigation, moderate and severe drought stress (irrigation after 70, 100 and 130 mm evaporation from standard class A evaporation pan, respectively) as main plots, two levels of clinoptilolite (0, 10 kg.ha-1) as sub plots and three hybrids of silage corn (KSC704, KSC705 and KSC720) as sub sub-plot. Study was conducted at Seed and Plant Improvement Institute in Karaj, Iran during 2013. Results of this study indicated that forage yield in mild (45133 kg/ha) and severe drought stress (38148 kg/ha) compared to normal irrigation regimes (56954 kg ha-1) decreased by 21% and 33%, respectively. Moreover, application of clinoptilolite resulted in 14% more forage yield (P<0.01). Forage quality parameters including water soluble carbohydrates, acid detergent fiber increased and total ash, total digestible nutrition reduced when there was moderate and severe drought stress imposition Application of clinoptilolite only increased total ash and had no significant effect on the rest of forage quality parameters. In this study, KSC704 hybrid produced highest forage yield (52030 kg.ha-1). Moreover, KSC705 had lowest acid detergent fiber content and neutrals detergent fiber content, highest dry matter intake and total digestible nutrition. Effects of irrigation regime and hybrid interaction on water-soluble carbohydrates and neutral detergent fiber of were significant at P<0.01 and P<0.05, respectively.