Aspectos fisiológicos e bioquímicos de plantas de catingueira e pereiro em função da sazonalidade sob condições semiáridas.

Abstract

The Caatinga biome, located in the Northeast of Brazil, is characterized by a semiarid climate, high solar incidence and low precipitation, which generates an environment of accentuated water deficit. The vegetation of this biome is composed mainly of trees and shrubs that adapt to adverse conditions, such as the Cenostigma nordestinum Gagnon & G. P. Lewis(catingueira) and the Aspidosperma pyrifolium Mart. & Zucc (pear tree). The study aimed to analyze the physiological and biochemical behavior of plants of these species during the dry and rainy periods, in the field, in the Brazilian semiarid region. The experiment was conducted on trees present at the Experimental Farm of the Núcleo de Pesquisas para o Trópico Semiárido (NUPEARIDO), of the Federal University of Campina Grande (UFCG), in Patos, Paraíba, Brazil, adopting a completely randomized design, 6 x 2 factorial scheme, referring to six months of evaluation (March to May - rainy season; July to September - dry season) and two years (2022 and 2023), with 4 replicates. The parameters relative water content (RWC), transpiration rate (E), stomatal conductance (gs), photosynthesis rate (A), intrinsic water use efficiency (A/gs) and foliar concentrations of organic solutes (total soluble sugars and total amino acids) were evaluated. The species presented different behavior between years, due to the variation in rainfall between them, developing different physiological strategies. During the dry period, in both years evaluated, catingueira plants presented values of E, gs, and A rate higher than those observed in pear plants, indicating more efficient stomatal behavior. The osmotic adjustment resulting from greater accumulation of soluble sugars and total amino acids during the dry period ensured greater cellular hydration in pear plants, enabling greater leaf RWC and greater control over gas exchange.