No abstract

Interaction of plant growth promoting microorganisms (PGPMs) with plants involves interplay at physical, physiological and molecular levels. Proliferation and root colonization of PGPMs manipulate the rhizosphere to optimize plant functions. This benefits plant by nutrient enrichment and induction of plant vigor and defense system. The present work aims to decipher the rhizosphere modulations promoted under different fertilization regimes by an organic acid producing Trichoderma koningiopsis strain (NBRI-PR5). Chickpea was selected as the host plant for the study since it responds well to the application of in/organic fertilizers and PGPMs. Microbial communities associated with the rhizosphere were studied by determining culturable population of heterogeneous microflora, and rhizosphere functions were studied by determining the soil enzyme activities and HPLC profiles of organic acids in root exudates. Application of NBRI-PR5 induced changes in rhizosphere in consent with the amendments. The changes observed in microbial populations were found to be associated with the rhizosphere enzymes. The inhibitory effect of chemical fertilizers on rhizosphere microflora was evident from least bacterial CFU observed in the NPK treatments. No detection of alkaline phosphatase enzyme in all the treatments with NBRI-PR5, with organic or inorganic amendments evidently represents the acidified rhizosphere. Similarly, an opposite trend in DHA and protease enzyme activities in the rhizosphere of FYM and FYM+PR5 treated plants showed that NBRI-PR5 had reframed microbial activities to facilitate nutrient uptake in plants rather than fix in the microbes. It is concluded from the study that NBRI-PR5 fatefully modulates rhizosphere activities, specific to different fertilization regimes by varying the enzyme activities to maximize the utilization of available nutrients.

No abstract

Sodic soil is increasing due to intensive cropping and imbalanced use of agrochemicals. Therefore, the objective of the present study was to reduce the soil sodicity in agricultural fields using sustainable resources. The 'microbe-residue-soil' interaction is hypothesized to foster the structural and functional changes during sodic soil reclamation. To elucidate the hypothesis, rice straw (RS) assimilation in sodic soil was instated in the presence of synergistically interacting Trichoderma koningiopsis NBRI-PR5 (PR5) and T. asperellum NBRI-K14 (K14) consortium. The interaction of the 'microbe-residue-soil' was investigated in-vitro and in sodic fields. Our studies included estimation of soil physicochemical properties, enzymes, CO 2 efflux using LI-COR, microbial population, scanning electron microscopy, and Fourier-transformed infrared spectroscopy (FTIR) analysis. The compatibility and synergism of PR5 assisted the K14 to produce laccase enzyme at high pH condition (pH 8) to degrade RS in sodic soil. For in vitro and field applications, Trichoderma were colonized on RS (TrichoRS) and applied at 25 t ha À1 . Impact of TrichoRS on soil was evident from decreased soil pH (9.6 to 7.8), exchangeable sodium percent (19.6 to 9.9%), increased soil porosity (~53% from 38%), and cation exchange capacity (~twofold). The FTIR showed differences in the stretching of O-H bonds at 3750-34500 cm À1 indicating the presence of more kaolinite-type silicates after TrichoRS amendment. Field application of TrichoRS increased the total organic carbon and water-holding capacity from 0.37% to 1.3% and 34% to 57%, respectively. Increased microbes and urease, protease, and phosphatase activity by 2.72-, 0.94-, and 0.88-times, respectively, ensured nutrient availability. The improved soil properties and ~30% increased production justify the hypothesis in providing sustainable reclamation solution for reviving fertility of sodic and intensively cultivated fields.

No abstract

No abstract

Intensive cropping is a major cause of depleting soil organic carbon (SOC) eventually leading to soil infertility. Restoration of depleted SOC requires renewable sources of organic amendments. Crop residue (CR), mostly lost due to burning in many parts of the world, is a generously available renewable source of organic carbon (OC) that can be used for soil recarbonization. The study presents an overview of the OC losses and pollution due to residue burning in India and explores the perspective of using surplus CR to restore SOC and promote ecosystem services for sustainable agriculture. We reviewed and quantified the magnitude of CR generated, and its fertilization potential in the Indo-Gangetic Region (IGR), an intensively cultivated region of India where rice straw burning is prevalent. A novel concept of interconvertible carbon triangle (ΔICC) is proposed based on the three carbon pools, SOC from the soil, CO2,/CO from the atmosphere and organic carbon (OC) from plant biomass to assess the instability of an agricultural land and estimate the SOC requirements based on the crop production data. The study reviews the availability of OC and other nutrients in CR and professes the need of technologies to divert the surplus CR to improving soil fertility and mitigate environmental pollution due to agricultural burnings.

No abstract