Eficiência de Gluconacetobacter diazotrophicus no aumento da tolerância de arroz vermelho à deficiência hídrica na fase inicial de desenvolvimento

Abstract

Drought is an of the main constraints to food production worldwide, as well as in the cultivation of red rice, which in Brazil is currently restricted to small areas of the northeastern semiarid. The water stress affects virtually all aspects of plants growth and development, with consequent reduced productivity. In this sense, the use of cultivars resistant to water stress is required, and the plant-microbe interaction, beneficial to plant growth and promote increased tolerance to biotic and abiotic stresses. According to the above, this study aimed to evaluate the agro nomic and ecophysiological aspects of red rice plants inoculated with Gluconacetobacter diazotrophicus under water stress in vegetative stage of development. The experiment was conducted under controlled conditions, with a completely randomized design in a factorial 2x4, with two conditions of inoculation, four water restriction levels (100, 70, 50 and 30% of field capacity), a rice genotype red (405 Embrapa Meio Norte), totaling eight treatments with four replications each. Each experimental plot consisted of a drainage lysimeter, which were planted 70 seeds, which after thinning was a total of 60 plants per plot. Water stress was imposed in the vegetative stage of development between stages V3 and V5, in a period of 15 days. The evaluations were performed after 15 days of water stress, growth variables were evaluated (leaf area, biomass), ecophysiological (gas exchange and chlorophyll a fluorescence) and productive (1000-grain weight and total mass of production). It was found that there was interaction between plants and G. diazotrophicus with positive responses, where possibly the endophytic bacteria used their growth promoting mechanisms and induction of tolerance to drought, as shown by increases in biomass and shoot as well as higher rates of photosynthesis and photochemical efficiency and increases in total productivity of plants inoculated with the bacteria. The results indicate that the inoculation was beneficial plants, and that the plant inoculation with G. diazotrophicus suppressed various water stress deleterious effects.