Gas exchange and water use efficiency in seedlings of tree species from caatinga under water levels and potassium

Abstract

This study aimed to evaluate the effects of water availability and potassium on physiological aspects of Myracrodruon urundeuva, Libidibia ferrea, and Mimosa tenuiflora seedlings. The experiment was conducted in a completely randomized design, factorial scheme 3 x 3, with three potassium doses [0, 97.5 and 195 mg dm-3 K] and three water levels [100%cv (control), 50%cv (moderate deficit) and 25%cv (severe deficit)]. The plants were kept in plastic bags containing 5 kg of substrate. Relative water content (RWC), transpiration (E), stomatal conductance (gs), net photosynthesis (A) and intrinsic water use efficiency (WUEi) were evaluated. The water deficit did not affect the RWC of L. ferrea and M. tenuiflora seedlings, but caused changes in the gas exchange in the species studied. During the initial phase of growth, M. urundeuva, L. ferrea and M. tenuiflora seedlings can be kept under conditions of low water availability in the soil. The M. urundeuva seedlings showed greater WUEi, even under severe water deficit. The use of K made it possible to maintain high E and A values, being able to be used to mitigate the effects of the water deficit, and we recommended using 195 mg dm-3 K.

Keywords

• anacardiaceae
• fabaceae
• mineral nutrition
• stomatal behavior
• water deficit