Effect of regulated deficit irrigation on vegetative growth, yield, fruit quality, and reserves accumulation of superior seedless

Abstract

Superior Seedless is a table grape cultivar mainly produced in San Juan. It has a short productive cycle (120 days) and a long lasting period between harvest and leaf fall (90 days), the consumption in this period is 45% of the total water required. The aim of this work was to develop a regulated deficit irrigation (RDI) strategy during post harvest, to reduce water and energy consumption, without affecting yield, fruit quality or reserves accumulation on next season. The treatments applied between harvest and leaf fall, were various fractions of estimated vineyard evapotranspiration (ET_c): control (C): 100%, T1: 50%; and T2: 25%. Midday water potential of T2 differed from the control. Values obtained during the application of the treatments ranged from -0.9 to -1 (C), -1 to -1.3 (T1) and -1.1 to -1.5 MPa (T3). The amounts of water applied after harvest to leaf fall were 775.97 mm (C), 408.06 mm (T1) and 234.31 mm (T2). Irrigation treatments did not affect starch and total nitrogen content in roots however in trunk, starch content was lower, and total nitrogen was higher in T2.  Pruning weight, budbreak percentage, shoot growth rate, yield and fruit quality were not affected by irrigation treatments, in the following season. It is possible to save water (up to 24%), applying regulated deficit irrigation after harvest (50% ET_c) without affecting yield, fruit quality or reserves accumulation in Superior Seedless.