Effects of biopreparations based on Bacillus and Trichoderma, combined with mineral and organic fertilization and a Pisum sativum L. forecrop on improving the tolerance of Maize plants to drought stress

The increased frequency of extreme weather phenomena, such as heat waves and drought, adversely affects the condition of plants. The need to strive for more sustainable methods of growing plants requires undertaking researches that focus on strengthening the immunity of plants using methods that have a positive impact on both crops and the natural environment. The aim of the study was to assess the effectiveness and compare the effects of selected microbiological preparations based on Bacillus bacteria and Trichoderma symbiotic fungi, combined with mineral (NPK) and organic fertilization (manure) and a Pisum sativum L. forecrop on improving the tolerance of maize plants to drought stress. The pot experiment was carried in 2023 as a two-factor experiment in three replicates. Physiological parameters were assessed based on measurements of photosynthetic efficiency (A - CO2 assimilation rate, E - Transpiration Rate, Gs – Stomatal Conductance) and chlorophyll content (CCI) and fluorescence (F0 - initial fluorescence, Fm - maximum fluorescence, Fv/Fm - maximum photochemical efficiency of PSII, Yield - quantum yield of the photochemical reaction in PSII, ETR – electron transport rate, NPQ - Non - Photo-chemical Quenching), as well as soil respiration (NCER- Net CO2 Exchange Rate, W flux- Net H2O Exchange Rate, Ce- Soil Respiration) and biometric measurements (dry mass of shoots and roots).The measurement of photosynthesis efficiency under drought stress clearly indicated the highest, significant effect caused by Trichoderma preparation with both fertilizers. In the control, CO2 assimilation was practically inhibited due to drought (98% drop), while in the plants in which the Trichoderma preparation was used together with half dose of NPK and manure, there was only a slight decrease (1% and 13% respectively). A greatest, significant improvement in the DM of roots under drought was noted in plants in which the Pisum forecrop was applied together with NPK and manure (230% and 168% respectively). Pisum forecrop and treatments with microbiological preparation containing Trichoderma, make it possible to reduce the fertilization dose by at least half. This is particularly important in view of the global trend of increasing drought stress and efforts to improve soil quality.