Exploring Crop–Microbiome Interactions Towards Improving Symbiotic Performance of Chickpea ( Cicer arietinum ) Cultivars Using Cyanobacterial Inoculants

The significance of integrated nutrient management practices is well established in improving the productivity of chickpea ( Cicer arietinum ); however, the effects of the inoculation of cyanobacterial inoculants on nodule metabolism, microbiome and associated genes are less explored. In the present investigation, cyanobacterium Anabaena laxa ( A. laxa) and biofilm developed using Anabaena torulosa , with Mesorhizobium ciceri as a partner ( An-M. ciceri ), were evaluated along with Mesorhizobium ciceri (M. ciceri ) alone, in three chickpea cultivars. Microbial inoculation led to 40–70% enhancement in nitrogen fixation, leghaemoglobin and ureide content, and two- to threefold increment in nitrate reductase and phosphoenolpyruvate carboxylase activity of the nodules. An enhancement of 30–50% in the soil available macro- and micronutrients and plant growth attributes was also observed. A significant correlation between the soil microbiological and plant parameters was recorded, particularly in relation to the nitrogen dynamics. Increases in the leghaemoglobin content in nodules due to An-M. ciceri, A. laxa and M. ciceri ranged from 18 to 40%, particularly in chickpea cv. BG372 in which 60–80% enhancement was recorded. Whereas the nifH gene copies in the nodule tissues ranged from 5.00 × 10 6 to 3.35 × 10 7 g −1 , the application of A. laxa led to higher abundances of nifH gene copies in desi chickpea cv. BG372 and kabuli BG1053 cultivars. An-M. ciceri , followed closely by A. laxa , was the top-ranking treatment, and chickpea cv. BG372 was the best performing cultivar; An-M. ciceri —chickpea cv. BG372 proved to be the superior combination for higher plant growth and soil nutrient-related traits.