Effect of Drought Stress and Bio-fertilizer on Yield and Yield Components of Guar Cyamopsis tetragonoloba (L.) Taub.

The effect of four different levels of irrigation periods, including normal irrigation, irrigation after 100, 150, and 200mm evaporation, with three different bio-fertilizer including control, Mycorrhiza, and Rhizobium were investigated on morphological and yield traits of guar. The experiment was conduct in form of split-plot design with irrigation periods as main plots and bio-fertilizers as sub-plots with three replications in research farm of Sarayan agricultural college-University of Birjand in2016.The results of analysis of variance showed significant effect of investigated irrigation periods on plant height, wilting, root length, pod length, number of pods per plant, grain yield, and biological yield at 1% probability level, and on chlorophyll content, height of the first branch, stem diameter, number of secondary branch, number of seeds per pod, and harvest index at 5% probability level. The interaction effect of drought stress xbio-fertilizers of bio-fertilizers was significant on wilting at 1% probability level and on chlorophyll and pod length at 5% probability level. The results of means comparison analysis revealed that the highest mean of wilting was achieved in severe drought stress induction in control, and application of both Mycorrhiza, and Rhizobium bio-fertilizers. Increasing levels of drought stress led to significant reduction in grain yield and harvest index of guar. Application of Mycorrhiza, and Rhizobium bio-fertilizers did not show significant effect on yield traits of guar under drought stress condition; however the protein percentage of guar's seeds was increased in moderate drought stress and inoculation with Rhizobium. Based on the results of simple correlation analysis biological yield and harvest index had the highest positive and significant correlation with grain yield of guar and can used as selection criteria under drought stress condition.