Effect of Rhizobium and Phosphate Solubilizing Bacterial Inoculants on Symbiotic Traits, Nodule Leghemoglobin, and Yield of Chickpea Genotypes

A field experiment was carried out during the rabi season of 2004-05 to find out the effect of Rhizobium and phosphate solubilizing bacterial (PSB) inoculants on symbiotic traits, nodule leghemoglobin, and yield of five elite genotypes of chickpea. Among the chickpea genotypes, IG-593 performed better in respect of symbiotic parameters including nodule number, nodule fresh weight, nodule dry weight, shoot dry weight, yield attributes and yield. Leghemoglobin content (2.55？mg？g？1 of fresh nodule) was also higher under IG-593. Among microbial inoculants, the Rhizobium + PSB was found most effective in terms of nodule number (27.66 nodules plant？1), nodule fresh weight (144.90？mg？plant？1), nodule dry weight (74.30？mg？plant？1), shoot dry weight (11.76？g？plant？1), and leghemoglobin content (2.29？mg？g？1 of fresh nodule) and also showed its positive effect in enhancing all the yield attributing parameters, grain and straw yields. 1. Introduction Pulses are the second most important group of crops after cereals. Developing countries contribute about 74% to the global pulses production and the remaining comes from developed countries. India, China, Brazil, Canada, Myanmar, and Australia are the major pulse producing countries with relative share of 25%, 10%, 5%, 5%, and 4%, respectively. In 2009, the global pulses production was 61.5 million tonnes from an area of 70.6 million hectares with an average yield of 871？kg/ha. Dry beans contributed about 32% to global pulses production followed by dry peas (17%), chickpea (15.9%), broad bean (7.5%), lentil (5.7%), cowpea (6%), and pigeonpea (4.0%). India is the largest producer and consumer of pulses in the world contributing around 25–28% of the total global production. About 75% of the global chickpea (Cicer arietinum L.) area falls in India [1]. Chickpea is one of the major post rainy seasonpulse crops in Madhya Pradesh, which occupies 3.09？m ha with production of 3.30？mt and productivity of 1071？kg？ha？1 [2]. The poor productivity of chickpea 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 chickpea productivity [3, 4]. Microbial inoculants are cost effective, ecofriendly, and renewable sources of plant nutrients [5]. 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 P-solubilizing species of Bacillus megaterium biovar phosphaticum, Bacillus