Bioestimulante em plantas e na qualidade pós-colheita de Capsicum annuum L. submetidas ao estresse salino

Abstract

Peppers are a vegetable of great socio-economic importance worldwide. It is one of the main vegetables produced in the world due to its ease of cultivation in small areas and its short cycle. The effect of salinity on plant growth and development is one of the biggest problems in arid and semi-arid regions, as these regions have an irregular rainfall regime and a high evaporation rate, with water generally having high salinity, thus leading to a reduction in agricultural production and even the death of plants. Alternatives to minimize the impacts of saline stress on plants involve the application of plant biostimulants, which are natural substances that improve nutritional efficiency, responses to abiotic stresses, productivity and crop quality. The aim of this study was to evaluate the efficiency of biostimulants in mitigating salt stress in bell pepper plants (Capsicum annuum L.). The experiment was conducted in pots in a greenhouse, using a randomized block design, in a 5 x 3 factorial scheme, with the factors being salinity levels (0.5; 1.5; 2.5, 3.5 and 4.5 dS m-1) and the application of the biostimulant in doses of 0, 0.3 and 0.6 mL L-1 of distilled water, with 5 repetitions. The parameters evaluated were: growth, productivity, gas exchange, relative leaf water content, chlorophyll index, chlorophyll fluorescence, dry matter accumulation, osmoregulators, antioxidant enzymes, oxidative damage and post-harvest physical and chemical analysis. The data was subjected to analysis of variance using the F test and, when significant, the treatments with the biostimulant were subjected to the Tukey test and the salinity concentrations to regression. The results showed that increasing salinity levels caused morphological changes in the plants, but weekly foliar application of the biostimulant alleviated the harmful effects of salinity stress on gas exchange, improved the balance of leaf water status and helped maintain photosynthetic pigments, reducing the damage caused to the photosynthetic apparatus of bell pepper plants under salinity stress. In addition, the biostimulant improved the growth, development, productivity and fruit quality of peppers under these stressful conditions. Both the 0.3 mL and 0.6 mL doses of the biostimulant proved to be effective in mitigating the effects of salinity on these plants. Therefore, the use of biostimulants can be considered a promising strategy for sustainable agricultural production in arid and semi-arid regions.