Development of microbial consortium for enhancing french bean (Phaseolus vulgaris L.) productivity
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Date
2018-11
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G.B. Pant University of Agriculture and Technology, Pantnagar - 263145 (Uttarakhand)
Abstract
An investigation to develop the microbial consortium for enhancing French bean productivity was carried out in the Central Analytical Laboratory, Department of Soil Science, Glass house (Department of Plant Pathology) in the College of Agriculture and Norman E. Borlaug Crop Research Centre of G.B. Pant University of Agriculture and Technology, Pantnagar, Uttarakhand during the years 2015-2018. Total fifty rhizobial isolates were isolated from the various soils of N-W Himalayan region of Uttarakhand out of which thirty-six were authenticated as French bean rhizobia employing the plant infection technique. Rhizobial isolates were Gram –ve rod and showed various PGP traits and enzymatic activities too. Two rhizobial isolates viz; RK19-2 and RB2-2 possessed all the tested plant growth promoting traits (IAA, GA, ammonia, HCN production and P-solubilization). Great diversity of French bean rhizobial isolates was observed in carbon source utilization in N-W Himalayan region. Out of 36, ten potential multi-trait rhizobial isolates were selected, based on various plant growth parameters which performed better or at par with that of reference strain MTCC 10096, for evaluating their efficiency at varying N-levels. Inoculation with multi-trait rhizobial isolates across the N-levels significantly improved various plant growth and physiological parameters, nutrient accumulation, amount of N2-fixed, quality of produce; and yield of French bean over uninoculated control. All the parameters, except nodulation, improved linearly with increased N-level giving highest at 100 kg N ha-1. Higher levels of nitrogen significantly reduced nodule number and nodule biomass linearly over lower levels. Rhizobial isolate RK3-1 produced highest nodule number at 0 kg N ha-1. RL21, RB8-2 and RA8 at 60 kg N ha-1 produced significantly higher and at par dry shoot biomass than that of MTCC x 100 kg N ha-1 . Highest amount of total N2-fixed was registered due to inoculation with RK3-1 at 100 kg N ha-1. PGPR1 (NAG-K3) with R1 (RD20-3) and R2 (RK3-1); and with R1 (RD20-3) were compatible to grow together in media whereas PGPR2 (CRC-J2) was not compatible with R2 (RK3-1). Inoculation of PGPR isolates namely NAG-K3 and CRC-J2 produced highest plant growth and physiological parameters. Inoculation of French bean with Rhizobium and PGPR, either alone or in combination significantly improved plant growth, physiological parameters, roots acid phosphatise activity, grain yield, amount of N2-fixed and produce quality over uninoculated control. Inoculation of PGPR1 (NAG-K3) along with R1 (RD20-3) and R2 (RK3-1) showed synergistic effect on different plant growth and physiological parameters, grain yield; and quality of produce whereas inoculation of PGPR2 (CRC-J2) with R1 (RD20-3) showed synergistic effect while with R2 (RK3-1) inhibitory effect was noticed. Highest grain yield was produced due to PGPR1 (NAG-K3) along with R1 (RD20-3) and R2 (RK3-1) at 100 kg N ha-1 followed by at 50 kg ha-1. From this investigation it was deduced that consortium comprising PGPR isolate NAG-K3 with rhizobial isolate RD20-3 and RK3-1; and PGPR isolate CRC-J2 with rhizobial isolate RD20-3 has the potential to increase the yield of French bean as well as to fix greater amounts of elemental nitrogen. Further studies are warranted to concretize the findings under field conditions.