Response of Sweet Pepper Varieties to Low-Input Conditions and Microbial Biostimulant Application

The excessive use of irrigation water and fertilizers in agriculture raises serious environmental concerns, emphasizing the need for more sustainable practices. Screening genotypes with reduced nutrient and water requirements, combined with favorable responses to plant growth-promoting rhizobacteria (PGPR), offers a promising strategy for developing more sustainable farming systems. Seven sweet pepper genotypes (Capsicum annuum L.) were evaluated under six treatments, involving two fertilization levels (100% and 50% standard dose), two irrigation regimes (100% and 75% full irrigation), and PGPR inoculation applied under reduced fertilization. Yield, fruit weight, rhizosphere enzymatic activities, and soluble sugars in green and red fruits were evaluated. The genotype effect contributed significantly to all traits. Combined reductions in fertilizer and irrigation decreased average yield by 21.7%, while PGPR did not fully compensate for these losses. Alkaline phosphomonoesterase activity increased by 22.9% under low fertilization, whereas averaged catalase and dehydrogenase remained relatively stable regardless of PGPR. In green fruits, PGPR inoculation under combined stress conditions increased glucose and fructose concentrations by 11.6% and 13.9%, respectively, compared to uninoculated stressed plants, although sucrose decreased. At fully ripe stage, sugar composition was less responsive to treatments. These findings underscore the importance of genotype evaluation and the exploitation of genotype × treatment interactions in peppers breeding for sustainable farming.