Metabolismo do carbono em progênies de Cupuaçuzeiro submetida à deficiência hídrica.

Abstract

In the Amazon, rainfall distribution is irregular, and distinct dry periods are common; water stress is known to reduce agricultural production. The objective of this study was to analyze the effect of water deficiency on leaf water potential, starch concentrations, total soluble carbohydrates, and sucrose in T. grandiflorum progenies exposed to 16 days of water restriction. The experiment was conducted in the greenhouse at Embrapa Amazônia Oriental. The seedlings were grown in plastic bags filled with 8 kg of pre-fertilized substrate. The experimental design was completely randomized, using a 2x7 factorial scheme. Each treatment was represented by five replicates, totaling 70 experimental units. An analysis of variance was performed on the results, and when a significant difference occurred, the means were compared using Tukey’s test (p<0.05) with the “SAS” software. Progeny 1074 showed the highest sensitivity to water restriction, with a significant reduction of 2,438% in leaf water potential. However, progenies 32 and 42 showed a significant reduction in starch concentration of 57% and 82% in the leaves, respectively; for the roots, progenies 57, 215, and 1074 showed reductions of 82%, 76%, and 69%, respectively. Therefore, a 16-day water deficit in Theobroma grandiflorum progenies led to a decrease in leaf water potential and starch content. At the same time, there was an increase in the concentration of total soluble carbohydrates and sucrose in all progenies subjected to water restriction.