Using of tolerance indicators to determine the best method for resistance to drought stress of forage corn S.C.540 in different levels of phosphorus fertilizer

To investigate integrated effect of biofertilizer and chemical fertilizer to tolerance forage corn (Single Cross Hybrid 540) under drought stress, an experiment was conducted as line source based on completely randomized block design with three replications in Agricultural Education Center of Shahid Naseri, Karaj, during 2012 - 2013. The implementation of line source was applied four levels of irrigation (not stress, mild stress, moderate stress, severe stress). Phosphorus factor was used in five levels including the application of 100% triple super phosphate fertilizer without biofertilizer, 75% recommended chemical fertilizer + biofertilizer, 50% recommended chemical fertilizer + biofertilizer, 25% recommended chemical fertilizer + biofertilizer, biofertilizer without chemical fertilizer. Results of experiment showed that GMP, MP, Harm and STI had positive and significant correlations with grain yield in both stress and non stress conditions in two years. The results of principal components analysis showed that two principal components approximately explained 100% of the total variance of yield in the both first and second years. Totally, results of stress tolerance indices in this research showed that application of the 75% recommended chemical fertilizer together with biofertilizer not only increased yield but also resistance of experimented variety to drought stress.