Yield and Some Physiological Characteristics in Maize by Application of Bio and Chemical Fertilizers Under Drought Levels

The effects of bio and chemical fertilizers on yield and some of physiological characteristics in maize under drought stress levels, were studied by an experiment in the research field of agricultural faculty, university of kurdistan in 2011. The experiment was arranged in split plot based on randomized complete block design with three replications. Three irrigation levels containing optimal irrigation (irrigation at soil water potential -3 bar), moderate drought stress (irrigation at soil water potential -7 bar) and severe water stress (irrigation at soil water potential -11 bar) were allocated to main plots and four fertilizer levels including no fertilizer (control), chemical fertilizer, bio-fertilizer and a combination of biological and chemical fertilizer (100% biological 50% chemical) were considered as sub factor. Results showed that water deficit stress had negative effects on yield, and the fertilizer application could not prevent reduction of grain yield under severe drought stress condition. The highest grain yield was obtained under optimum irrigation and application of combinational treatment chemical fertilizer phosphate-biofertilizer nitroxin with an average of yield 13 ton.ha-1 that showed a 257 percent increase in comparison with control. The chlorophyll a content was decreased, but chlorophyll b content was decreased with increasing stress intensity. The results showed that catalase and peroxidase enzymes activity were increased in drought stress conditions more than optimal irrigation condition. The application of fertilizer partly mitigated the effects of drought stress and reduced antioxidant enzymes activity.