EVALUATION OF BIOLOGICAL FERTILIZER ON PROTEIN CONTENT AND ENZYMATIC ACTIVITIES IN MAIZE (HYBRID 704 VAR.) UNDER WATER STRESS CONDITIONS IN TWO YEARS
To evaluate the effect of integrated phosphorous fertilizer on the trend of biochemical variations in maize (hybrid 704 var.), an experiment was conducted during 2011 and 2012. The experiment was conducted in a split plot design based on randomized complete block design with three replications. The main factor was drought stress in three levels (control (no drought stress), moderate drought stress and severe drought stress) and subplot factor was phosphorus fertilizer in five levels (control (no fertilizer application), 100% required triple super phosphate (according to soil test), 75% triple super phosphate+biological fertilizer, 50% triple super phosphate+biological fertilizer and 25% triple super phosphate + biological fertilizer). Yield and growth parameters including fresh and dry forage yield, total protein, as well as enzyme components like catalase enzyme, super oxidase, and super oxide dismutase were measured. The results showed a significant effect of phosphorous fertilizer on all measured parameters. The interaction effect of fertilizer and drought stress conditions were only significant on forage yield, catalase, and super oxidase enzymes. The highest fresh forage yield was obtained from 100% triple super phosphate in both experimental years. The catalase, super oxidase, and super oxide dismutase enzymes activities in plant tissue increased as the phosphorous concentration in P fertilizer increased. However, in integrated fertilizer treatments, the enzyme activities were significantly lower. Biological fertilizer application modified the adverse effect of drought stress through decrement of these enzymes activities in the plant tissues. There was a significant and negative correlation between fresh forage yield and all three enzymes activities at drought stress conditions. The highest correlation existed between fresh forage yield and super oxide dismutase enzyme activity in plant at drought condition.