The preventive impact of vermicompost on bell pepper (Capsicum annuum L.) salinity resistance: An evaluation

This work aims to identify the impacts of vermicompost leachate (VCL) toward its salt resistance stress in plants. Young Capsicum annuum L seedlings were subjected to salinity (160 mM NaCl added to a nutrient solution) over a course of seven days during or following the adding of 7 mL L−1 VCL. The exposure to salt stress resulted in a notable decrease of dry and fresh leaf weights, K+ concentrations, and leaf water content; whereas leaf and root Na+ concentrations were remarkably increased. Furthermore, the salt stress yielded reduced instantaneous transpiration, net photosynthesis, maximum PSII photochemistry efficiency, stomatal conductance (gs) in the state of photochemical quenching, dark adaptation, and photochemical efficiency of PSII (ΦPSII). Moreover, VCL application in the state of salt stress led to an increase of leaf fresh weight and gs, while the leaf osmotic potential remained consistent regardless of the proline content increase seen in the salt-treated plants. Meanwhile, it minimized the Na+ concentration in the leaves by 21.4%, and increased in the roots by 16.9%. Accordingly, a pre-treatment regiment with VCL and the ensuing salt stress yielded higher efficiency compared to its concomitant application with salt stress due to the pre-treatment recording the highest osmotic adjustment. VCL pre-treatment resulted in sugar concentration in the roots (9.3 µmol g−1 FW) and the maximum level of proline in the leaves (51 µmol g−1 FW). Additionally, the fluorescence-linked parameter reaffirmed superior outcomes for the PSII stability and efficiency in the case of VCL pre-treatment on salt-stressed plants in contrast to those subjected to concurrent VCL salt stress exposure. Hence, VCL is proven to be an effective defense medium towards enhancing the property of salt-stress resistance in bell peppers.