Appraisal for organic amendments and plant growth‐promoting rhizobacteria to enhance crop productivity under drought stress: A review

Abstract

Plants are sessile organisms, frequently face unfavourable growth conditions such as drought, salinity, chilling, freezing and high‐temperature stresses, inhibiting growth and development, and ultimately reducing crop productivity. Among these stresses, drought stress has been a major challenge for sustainable crop production and a hot area of research under the current climate change scenario. Organic amendments such as biochar (BC) and compost along with plant growth‐promoting rhizobacteria (PGPR) could be a sustainable strategy to improve crop growth and productivity under drought stress environment. There are several reports about compost, BC, and PGPR application as a single or combined treatment to enhance crop productivity under drought stress. Compost and BC act as conditioners to improve soil physicochemical and biological properties thereby enhancing water holding capacity (WHC) and nutrient retention and availability to the plants. Both BC and compost also serve as carbon sources and suitable environment for PGPR and endogenous microbes to enhance their growth promotion activities under drought stress. PGPR alleviate drought stress via ACC‐deaminase and P‐solubilizing activities, production of phytohormones, secretion of organic acids, acting as biocontrol agents,etc. In the present review, the individual and combined effect of compost, BC, and PGPR to alleviate drought stress in plants has been critically summarized. Moreover, research gaps and future research directions have been identified and discussed in depth.

Comparative Analysis of Plant Growth-Promoting Rhizobacteria (PGPR) and Chemical Fertilizers on Quantitative and Qualitative Characteristics of Rainfed Wheat

“…PGPR are eco-friendly efficient biotechnological tools to improve plant water uptake and growth in various, especially stressful, conditions [18]. PGPR application is a sustainable strategy for increasing crop production under drought stress and replacing chemical fertilizers [29]. In the present study, the yield components of the Azar-2 rainfed cultivar, including biological yield, grain yield, straw yield, and 1000-seed weight, were significantly affected by the applied F, B, N1, and N2 PGPR as seed-inoculated plants showed higher means than noninoculated controls.…”

Comparative Effects of Bio-Wastes in Combination with Plant Growth-Promoting Bacteria on Growth and Productivity of Okra

“…The results of our study are in agreement with the findings obtained by Ahmad et al [52], who reported that co-inoculation of Rhizobia and PGPR can enhance root length and cause an increase in the uptake of water from deeper soil regions. Ullah et al [53], Mumtaz et al [54] and Fatawi et al [55] argued that the use of rhizobacteria and organic amendments (compost and biochar) increases the root surface area, root length and stomatal conductance, that, in turn, improve the absorption of water from deeper regions and ultimately result in an increase in RWC. Co-inoculation of PGPR and Rhizobium possessing ACC-deaminase activity promotes roots elongation that aids the plant to absorb more water from soil [49].…”

Biochar for the Management of Nutrient Impoverished and Metal Contaminated Soils: Preparation, Applications, and Prospects

“…Healthy soil is essential for plant growth in the natural environment. In the recent past, various environmental and ecological issues such as soil contamination, soil degradation, fertility loss with a decline in crop yield, water shortages, and climatic change have led to an increased trend in biotic and abiotic stresses that ultimately pose a threat to food security (Gregory et al 2014;Ren et al 2016;Albert et al 2021;Saffeullah et al 2021;Ullah et al 2021). Soil contamination through inorganic and organic contaminants is a well-known problem; therefore environmentally safe and economically viable remediation techniques are urgently needed (Ren et al 2016;Mehmood et al 2019).…”