Bacillus subtilis LPM1 differentially promotes the growth of bell pepper (Capsicum annuum L.) varieties under shade house

AbstractBacillus subtilis strain LPM1 was previously documented as a plant growth-promoting rhizobacterium under open field conditions. For deeper understanding, the present study was established in a shade house with three different commercial varieties of bell pepper (Prosperity RZ, Valkiria RZ, and Sven RZ) treated prior to transplanting with the B. subtilis LPM1. The trial was performed as three parallel experiments (one per variety) comparing treated (LPM1 inoculated) against untreated (control) plants, with four replicates each. At three different times i.e. 30, 45, and 60 days after inoculation (DAI) biometric parameters, including total dry biomass, foliar area, plant height, stem diameter, and total yield were measured. Physiological parameters such as photosynthetic rate (µmol CO2 m−2 s−1), stomatal conductance (mol H2O m−2 s−1), and transpiration rate (mmol H2O m−2 s−1) were also evaluated. In the vegetative stages, the rhizobacterium B. subtilis LPM1 significantly promoted some plant traits of bell pepper varieties, such as stem diameter and total dry biomass (30, 45, and 60 DAI). However, the fruit number and yield in bell pepper varieties did not show differences between treatments under shade house conditions