Gas Exchange and Photochemical Efficiency of Caatinga Plants Submitted to Different Water Management Strategies

Abstract

Water availability is a critical point for dryland recovered on tropical regions of the world. This problem to become higher with the lacking information about the ecophysiologial behavior of the native plants on the initial growth stage under field conditions, mainly when these plants are submitted to different water availability levels. To address this question, we evaluated different water management strategies on the ecophysiological features of the five young native plants establishment in a degraded area located in the Caatinga, a dryland Brazilian forest. The water management strategies effects on native plants were checked by analyzing the photosynthesis rates, gas exchange and photochemistry efficiency in leaves of Crataeva tapia, Erythrina mulungu, Handroanthus impetiginosus, Tabebuia aurea and Ziziphus joazeiro. The experiment had four treatments (waterbox use, bovine manure, hydrogel, bovine manure plus hydrogel) and control. In the initial growth stage and under field conditions, the effects of water stress or water deficiency on the photosynthetic rates, gas exchange and chlorophyll fluorescence a of the T. aurea, H. impetiginosus, C. tapia and E. mulungu, exposed to waterbox and hydrogel, associated or not with bovine manure, were partially or totally mitigated. The Z. joazeiro species has the adaptive intrinsic characteristics that allow them to with stand the most stressful environmental conditions and this naturally allowed presenting greater water use efficiency and absence of damage to the photosynthetic apparatus and high Fv/Fm ratio. In general, the water management strategies studied have alleviated the effects of water stress, totally or partially, on the ecophysiological processes of young native plants under field conditions.