Microbial-priming of seeds with plant growth-promoting rhizobacteria and arbuscular mycorrhizal fungi for improving cotton (Gossypium barbadense L.) growth, yield and water productivity under drought stress

Cotton is particularly vulnerable to water deficit stress, resulting in substantial reduction in both its growth and yield. Therefore, the aim of the present study was to assess the effectiveness of extending irrigation intervals (to every 30, 45 days) compared to well-irrigated plants (every 15 days). Additionally, in an effort to mitigate adverse effects of water deficit stress, cotton seeds and soil were inoculated with Bacillus amyloliquifaciens, Funneliformis mosseae, either individually or in combination. The study was conducted over two summer seasons in 2021, 2022. Results revealed that extending irrigation intervals had negative impact on mycorrhizal colonization, and various plant growth or productivity parameters, including, plant height, leaf area, dry weight per plant, number of fruiting branches and bolls per plant, lint percentage, seed index, seed yield, fiber quality. Furthermore, physiological, or biochemical characteristics, including chlorophyll pigments (chl.a, b and total) and leaf relative water content were adversely affected by prolonged irrigation intervals. Biopriming of cotton seeds with rhizobacteria that promotes plant growth and arbuscular mycorrhizal fungi was found to improve plant height, leaf area, plant dry weight, number of fruiting branches and bolls/plant, yield and yield component, chlorophyll pigments, as well as enhance efficiency of antioxidant enzyme activity (catalase, peroxidase and polyphenol oxidase), leaf total phenols and proline contents. Biopriming cotton seeds presents hopeful strategy for boosting cotton yield, reducing effects of drought stress and fostering soil fertility.