Gas exchange, chlorophyll fluorescence and stem water potential preliminary analysis of jujube tree in a semi-arid region of Sergipe, Brazil

Abstract

This work aimed to perform an preliminary analysis of the gas exchange, chlorophyll fluorescence and stem water potential of jujube tree (Ziziphus joazeiro Martius) under field conditions in a region in Alto Sertão (dry land) in the State of Sergipe, in order to understand the survival strategies used by this species to the local climate, with low rainfall and high levels of temperature and solar radiation. Thus, we evaluated: the efficiency of photosystem II (Fv / Fm and Fv/F0 ratio), the area of the OJIP curve and performance index (PI), besides the photosynthetic rate, stomatal conductance, transpiration and stem water potential. The fluorescence data showed that individuals had normal rates indicating no stress condition. The rate of photosynthesis (A) was higher in the morning, where the stomata are open and fully functional photosystem and decreased gradually throughout the day until reaching negative values in the afternoon, where stomatal conductance (gs) and transpiration rate (E) were also lower thereby avoiding excessive loss of water. The stem water potential (Ψw) varied throughout the day, being more negative in the morning. It was concluded that this species presents efficient strategies for survival, keeping your tissues hydrated at times with higher temperatures and lower relative humidity and assimilate at times when conditions are more favorable, thus avoiding excessive loss of water.