One of the main challenges in pepper production is to enhance seed germination energy and germination, and to grow healthy nursery plants with strong root system. Trichoderma species colonize roots as they grow and provide season-long benefits to plants, which is why Trichoderma species are widely used as plant growth promoter agents and promoters of plant defence mechanisms. This study evaluated the effectiveness of seed biopriming with Trichoderma isolates for growth promotion of pepper plants in early stage and their effects on seedling physiology. Nine out of ten Trichoderma isolates positively affected root weight of pepper seedlings, while three out of ten positively affected shoot weight. Root and shoot lengths were mainly unaffected. Germination energy was positively affected by five isolates with up to 40% increase compared to the control, while germination was significantly enhanced by two isolates with up to 22% increase. Considering seedling physiology, two different strain-dependent modes of actions were expressed. Promising Trichoderma isolates induced formation and accumulation of reactive oxygen species (ROS) which acted as signal molecules that increased germination energy and germination. Positive correlation was found between pyrogallol peroxidase, superoxide dismutase, catalase activity and germination in plants treated with these isolates.

We examined the effect of drought-tolerant Bacillus safensis SS-2.7 and B. thuringiensis SS-29.2 strains on the response of four (133, 274, California Wonder—CalW, and Matica) sweet pepper genotypes to water deficiency conditions. Pepper seeds were sown in pots with (treated) and without (control) bacterial strain inoculation. After four weeks of growth under controlled conditions and regular watering, drought was imposed by completely withholding watering for seven days. Under conditions of normal watering, genotype 274 showed better seedling establishment than genotype 133 and CalW, while the slowest was genotype Matica. Antioxidant enzyme activity under drought conditions was genotype and bacterial treatment-dependent. The best response to bacterial treatment in order to cope with severe drought was found in the CalW genotype, while in genotype 133, we determined even faster plant decay during water deficiency in treated seeds. Inoculated seeds of the Matica genotype did not show different antioxidant enzyme activity under normal and drought conditions. According to the obtained results, we concluded that under drought conditions, the most susceptible was genotype 274, moderate susceptibility was detected in genotype 133, and CalW and Matica were the most tolerant genotypes. Our study demonstrates (1) that drought-tolerant Bacillus strains showed a plant growth-promoting effect on some selected pepper genotypes; (2) that there were genotype-dependent antioxidant enzyme activities under drought conditions in response to treatment with a particular bacterial strain; and (3) that we could expect a genotype-dependent response during biostimulant application, especially under stress conditions.

Pepper is very popular vegetable crop in Southeast Europe and in Serbia as well. Wide genetic variability is essential in pepper breeding programs. The aim of this study was to evaluate variability for the most important fruit traits and differences between 28 sweet pepper genotypes from the working collection from the Institute of Field and Vegetable Crops (Novi Sad, Serbia). The following traits were analyzed: fruit weight (g), fruit length (cm), fruit diameter (cm), fruit index, number of locules, number of apexes, pericarp thickness (mm), and total soluble solids (?Brix). Results confirmed great variability in evaluated pepper fruit traits. Genotypes were separated into individual groups based on fruit characteristics. According to our research, hierarchical cluster analysis represented differentiation among groups of genotypes more clearly than PCA, but not comparing to k-means. Hierarchical cluster analysis showed the similarity between genotypes, but k-means clustering did not. Genotypes from group 3 will be used in breeding for higher fruit weight and group 6 for thicker pericarp.