Impact of Bacterial Dual Inoculation (PSB and Rhizobium) on Nodulation Behavior and Biomass of Sand Culture Grown Kulthi (Dolichos biflorus)

Out of 135.00 lakh ha (1.35 lakh sq km) area of Chhattisgarh, about 46.02 lakh hectares is under kharif mostly with rice crop while about 12.45 lakh ha only under rabi crops. About 30.00 lakh ha area remains fallow during rabi. Horse gram (locally known as kulthi in Chhattisgarh) is one of the unexploited legumes of the tropics and subtropics grown mostly under dry-land agriculture. It is important pulse crop taken in tribal belt of the Chhattisgarh. In Chhattisgarh total cultivated area of this crop is about 75 thousand hectares, out of this, nearly 37 thousand hectares are situated only in Bastar Divison representing an important kulthi belt in the state. This crop is very popular among the marginal and poor farmers which includes mostly tribal population of Chhattisgarh. The important International Journal of Current Microbiology and Applied Sciences ISSN: 2319-7706 Volume 7 Number 06 (2018) Journal homepage: http://www.ijcmas.com

The present investigation was carried out in green house of Department of Agricultural Microbiology, Indira Gandhi Krishi Vishwavidyalaya, Raipur, Chhattisgarh (India) during the year 2015-16. The co-inoculation of Rhizobium + PSB at 45 DAS significantly increased no. of root nodules per plant, biomass of nodules, shoot biomass accumulation and N accumulated by shoot over control plants. Plants were allowed to grow up to 45 days under sand culture, data of plant biomass revealed that the highest dry shoot weight was (0.156 gm/plant) associated with combination of Rhz-10+PSB-142 followed by isolate Rhz-10+PSB-184 (0.137 gm/plant). Similarly, highest dry wt. of nodules was observed 1.70 mg/plant due to combinations of Rhz-10+PSB-142 followed by isolate Rhz-10+PSB-118 (1.52 mg/plant), while the highest number of nodules (6.33 per plant) associated with combination of Rhz-10+PSB-142 followed by Rhz-10+PSB-118 (5.66 per plant). The shoot N accumulation study of the same sand culture experiment indicated that highest shoot N-uptake associated with combination of Rhz-10+PSB-142 (4.57 mg/plant) followed by Rhz-10+PSB-184 (3.94 mg/ plant). Hence, is concluded that combination of Rhz-10+PSB-142 is the most potent N2 fixer for kulthi cultivation in acidic soils of Chhattisgarh.
kulthi growing districts of Chhattisgarh are Jagdalpur, Kanker and Surguja. Total area, production and productivity of kulthi in Chhattisgarh is 17.70 thousand ha, 5.75 thousand ton and 3.25 quintal per ha respectively (Anonymous, 2009-10). The productivity per unit area of this crop is very low mainly because of sub optimal nutrition including low or ineffective native population of N fixing and P solubilizing microbes 2000a).
The poor productivity of kulthi in this region is mainly due to imbalance application of nutrients and use of traditional varieties. Under such situations, use of Rhizobium and phosphate solubilizing bacteria (PSB) had shown advantage in enhancing kulthi productivity. Microbial inoculants are cost effective, ecofriendly, and renewable sources of plant nutrients (Khan, M.S. et al.,, 2007). Rhizobium and PSB assume a great importance on account of their vital role in N2-fixation and P-solubilisation. The introduction of efficient strains of Psolubilizing species of Bacillus megaterium biovar phosphaticum, Bacillus polymyxa, Pseudomonas striata, Aspergillus awamori, and Penicillium digitatum in the rhizosphere of crops and soils has been reported to help in increasing phosphorus availability in the soil (Gaur, A.C. et al.,, 1990). Since the information on response of nodulation behavior of kulthi to inoculation with Rhizobium and phosphate solubilizing bacterial inoculants is meager under such situation, therefore, an experiment was designed to assess the productivity of kulthi.

Treatments Details and Crop Culture
The experiment was conducted during the kharif season, 2015-16. The experiment was laid out in CRD design with three replications.

Nodulation, Shoot biomass and N accumulation
After 45 DAS the sand culture grown plants were uprooted, then number of nodules per plant and other observations were recorded. The nitrogen accumulated in the plant samples was estimated by Micro-Kjeldahl method as described by Jackson (1973) using auto digestion and distillation system.

Statistical Analysis
Statistical analysis of data was carried out using online statistical analysis pack-age (OPSTAT, Computer section, CCS HAU Hisar, Haryana) for calculation of ANOVA.

Nodulation Study
The data presented in (Table-1) indicated that at 45 DAS, the highest no. of nodules per plant, fresh weight of nodules (mg/plant) and dry weight of nodules (mg/plant) increased significantly due to all treatments over control plant.
Similar observations were also reported by Gupta et al., (2000) and Gupta et al., (2005), Kalita et al., (2006); Garg (2010) and Sharma et al., (2012).They mentioned that the Rhizobium isolate was most effective in respect to increase number of nodules, nodules fresh weight and nodules dry weight in legumes. Saleh et al., (2013) clearly mentioned that Rhizobium inoculation improved nodulation in the varieties of urad bean than that of uninoculated control plant.

N-accumulation study
Data presented in (  Miyan et al., 1989. They clearly mentioned that dry matter yield and N-uptake by rajma legume can be increased by use of specific Rhizobium strains. Based on above results, it can be concluded that combination of Rhz-10+PSB-142 (T 9 ) is superior over the remaining treatments with respect to nodulation, shoot biomass and accumulated N by shoot. However use of Rhizobium and PSB inoculation had also shown advantage over no inoculation. Thus, co-inoculation of Rhizobium and PSB may be recommended to realize higher nodulation of kulthi.