Ecofisiologia de genótipo de algodoeiro sob déficit hídrico e aplicação de ácido pirúvico.

Abstract

Water deficit is an important abiotic factor that negatively affects crop growth and productivity. Pyruvic acid participates in the process of breaking the glucose molecule into two molecules of pyruvic acid, essential in the metabolism of the Krebs cycle and in the respiratory chain, resulting in the production of ATP molecules, vital for the development of plants, however, the studies on the effects of its exogenous application on plants are scarce. In this context, the objective was to evaluate ecophysiological parameters of cotton genotypes cultivated under water deficit and application of pyruvic acid varying the phenological phase of the crop. The research was carried out in a greenhouse, in pots with 25 dm3 of soil. For this purpose, three cotton genotypes (BRS Seridó, CNPA 7MH and FM 966) were tested and submitted to four treatments (C – control, full irrigation, C+P – Control + application of pyruvic acid, E – water deficit and E+P – water deficit and application of pyruvic acid) evaluated in two phenological phases (vegetative and flowering), distributed in randomized blocks in a factorial scheme (3×4) with 3 replications. The effects of treatments on cotton were evaluated using: analysis of gas exchange, chlorophyll fluorescence and growth variables, water productivity and production components. In the vegetative phase, pyruvic acid is efficient in reducing the effects of water deficit on gas exchange and water productivity. Plants of the BRS Seridó genotype under full irrigation, when pyruvic acid is applied, obtain higher seed cotton production, while the variable fluorescence, maximum fluorescence, boll mass and seed cotton production of the FM 966 cotton plant reduces with water deficit. In the flowering phase, the water deficit decreases with greater intensity the number of bolls, boll mass, seed cotton production and water productivity in cotton FM 966 compared to BRS Seridó and CNPA 7MH. Foliar application of pyruvic acid reduces the deleterious effects of water deficit on maximum PSII quantum efficiency (Fv/Fm) and PSII photochemical efficiency (Fv/Fo) in plants of the CNPA 7MH genotype. Cotton plant water productivity under full irrigation increases with foliar application of pyruvic acid. The water deficit in the vegetative phase is less harmful to the cotton crop than in flowering.