Effect of Arbuscular Mycorrhizal Fungi and Pink Pigmented Facultative Methylotrophs for Mitigating Water Stress in Black Pepper

Water stress is one of the most apparent abiotic factors limiting black pepper plants' establishment, growth, and production. Many crop plants benefit from arbuscular mycorrhizal fungi (AMF) and pink pigmented facultative methylotrophs (PPFM) that help them withstand water stress. In this study, the beneficial interactions of these microbes are exploited to alleviate the ill effect of black pepper plants, while exposing them to different levels of water stress. An experiment was conducted during 2018–2020 with the Panniyur 1 variety of black pepper and induced water stress under greenhouse conditions. The interaction effect was compared with control plants raised under water stress and normal irrigation without the association of any beneficial microbes. By exposing the experimental plants to various levels of water stress, the extent to which association of each bio agent helps in reducing the quantity of irrigation water without any compromise on plant growth and yield was also studied. In comparison to control plants with and without water stress, the results showed that combining AMF with 25% and 50% water stress and PPFM with 25% water stress considerably improved the vegetative character of the plant (P < 0.05). These beneficial microorganisms maintained a greater relative water status and total chlorophyll content during the whole experimental period. When the water deficit period was extended for three months, the concentration of carotenoid and proline in plants increased exponentially, which assisted in alleviating water stress in black pepper. Contrast analysis of the data revealed that the above water stress mitigating factors were higher in AMF linked plants than PPFM treated plants.