Atuação do brassinosteróide no crescimento de mamoeiro sobre déficit hídrico

Abstract

Brazil is one of the world's largest producers of papaya (Carica papaya L.). In the Northeast region, more than half of the national production is concentrated. Nevertheless, one of the main limiting factors of the productivity of this culture in this region is the irregularity of the rains. In this context, the objective of this study was to evaluate the brassinosteroid action under the growth characteristics and osmotic mechanisms in the papaya cultivated under irrigation slides. The experiment was conducted in an experimental field at the State University of Paraíba, Catolé do Rocha-PB municipality, using seeds of the cultivar Havaii. Were tested five irrigation slides (60, 80, 100, 120 and 140% of reference evapotranspiration) and three brassinosteroid concentrations (0, 0.5 and 1.0 mg L-1) using a randomized block design, In the 5 x 3 factorial scheme, with four replicates. At 120 days after emergence, the growth and biochemical characteristics were analyzed, being analyzed by F test until (p ≤ 0.05) and for the q uantitative factors polynomial regression analyzes were performed. It was observed that the brassinosteroid influenced the growth of papaya, mainly in the secondary meristem. It was observed that the brassinosteroid influenced the growth of papaya, mainly in the secondary meristem. The content of free amino acids was reduced and there was an increase in soluble protein content with increased irrigation and application of the hormone. Thus, papaya can be irrigated during the vegetative phase, adopting 80% of the reference evapotranspiration when treated with the dose of 0.5 mg L-1 of BR, a fact verified mainly by the analysis of the growth characteristics of stem diameter, leaf area, dry stem mass and root volume. As well as the increase of non-reducing carbohydrates, soluble proteins and the chlorophyll content.