Improvement of some growth indices of common bean using mycorrhiza and rhizobium under different levels of starter nitrogen fertilizer

Abstract

To evaluate the effect of using mycorrhizae and rhizobium at different levels of nitrogen starter fertilizer on some important growth indices of a common bean cultivar, a factorial experiment was conducted in a randomized complete block design with three replications in 2016 at Bu-Ali Sina University research farm. The factors included two bio-fertilizers of mycorrhizae (Glomus mosseae) and rhizobium (Rhizobium phaseoli) each one with two levels (used and non-used) and nitrogen starter fertilizer with three levels (0, 30, 60 kg ha−1) from urea as the third factor. The studied factors caused significant changes in growth indices. The maximums of leaf area index (5.9), total dry weight (860 g m−2) and crop growth rate (44 g m−2 day−1) were observed in the simultaneous application of both bio-fertilizers plus use of 60 kg ha−1 N. This superior treatment compared with no bio-fertilizer + 60 kg ha−1 N treatment increased maximums of LAI, TDM and CGR, 115, 68 and 60%, respectively. Also in superior treatment, the two indices of net assimilation rate (NAR) and relative growth rate (RGR) on 60th day after planting were 25 g m−2 day−1 and 0.046 g g−1day−1, that were respectively 116 and 17% higher than no bio-fertilizer + 60 kg ha−1 N treatment. Therefore application of mycorrhiza and rhizobium simultaneously in addition to 60 kg ha−1 N as starter fertilizer is an appropriate treatment in common bean to maximize the growth indices.