Differential tolerance to water deficit in two açaí (Euterpe oleracea Mart.) plant materials

Two acai plant materials (BRS-PA cultivar and Hideo ecotype) were subjected to differential irrigation to examine its potential tolerance to water deficit. Seedlings were grown for 45 days under irrigation replacing different volumes of water required to the soil reaches field capacity (FC). The irrigations replaced 100% FC (control treatment), 70% FC, and 40% FC (water deficit treatments). The Hideo ecotype showed more significant decreases in leaf water potential than BRS-PA. The former showed lower net CO2 assimilation rate (A), stomatal conductance (gs), transpiration and instantaneous water use efficiency, particularly under irrigation of 70% FC. In Hideo, the decreases in A mediated by water deficit were coupled to chlorophyll (Chl) degradation. In BRS-PA, the A and Chl content were decreased only under 40% FC. Starch content was unchanged between plant materials irrigated with 70% FC; however, it was decreased in Hideo seedlings irrigated with 40% FC. Accumulation of total soluble carbohydrates, glucose, and fructose has occurred in Hideo ecotype under 70% FC and in both plant materials under 40% FC. The water deficit caused more striking decreases in Hideo growth than in BRS-PA, especially by reducing leaf dry matter, root dray matter (under 70% FC), and both total and specific leaflet areas. Under irrigation with 40% FC, plant material differences in growth variables were negligible. The results indicate that BRS-PA cultivar tolerate mild water deficit (70% FC) more satisfactorily than Hideo; however, both plant materials were equally sensitive to more severe water deficit (40% FC).