Ecofisiologia do algodoeiro sob estresse hídrico variando a fase fenológica e a suplementação de piruvato.

Abstract

Cotton is one of the main crops explored, commercially in the semi-arid region of Brazil, moving several sectors of the economy, generating employment and income. In rainfed cotton farming, production, in general, is low, due to climatic factors, resulting from the low and irregular distribution of rainfall, which highlights the importance of studies aimed at minimazing the effects of drought on its cultivation. This work aimed to evaluate the ecophysiology and water stress tolerance of naturally colored cotton, cv. BRS Jade, in germination and varying the phenological phase, with pyruvate supplementation. The experiment was carried out in a protected environment, belonging to the Agricultural Engineering Academic Unit of the Federal University of Campina Grande. Two forms of seed pre-soaking were studied (distilled water and calcium pyruvate solution), two hydric availability (water deficit and irrigated) and application of calcium pyruvate in three phenological phases (vegetative, flowering and vegetative plus flowering), plus an absolute control (without pre-imbibition, full irrigation and without application of pyruvate) in a randomized block experimental design, 2 x 2 x 3 + 1 factorial scheme. Combined, the factors resulted in 13 treatments, with three replications and two plants per plot, totaling 39 experimental units. Emergence, growth, physiology and production components were evaluated. It was found that there was no difference between the forms of imbibition and that water stress in the flowering and vegetative plus flowering phases reduced the gas exchange of cotton plants. However, the exogenous supply of pyruvate, from calcium pyruvate, at a concentration of 100 mM, attenuated the effects of water deficit in the vegetative phase, notably in the variables of growth, mass accumulation and production, increasing the mass of full boll, mass of lint with seed and boll number of cotton cv. BRS Jade. Calcium pyruvate supplementation also reflected in better water use efficiency (1.32 g L-1) in cotton plants, thus being indicated to the producer.