Growth and quality of apples as affected by different irrigation treatments

Abstract

SummaryGranny Smith apple trees were irrigated at four levels of total available soil water (TAW)* in the soil, viz. 85%, 65%, 45% and 25%. The treatments were applied during each of four phenological phases of the trees for four years. Soil water potentials at the time of irrigation were – 19 kPa and – 1189 kPa, respectively, for the 85% and 25% TAW levels. Total irrigation amounts varied between 570 mm and 850 mm, the recommended amount being 600 mm of water. A significant linear increase in fruit circumference growth with an increase in TAW level was observed for phenological phases 2 and 3. The main part of total growth was completed during phase 2. The tendency for fruit growth to decrease over years was probably due to increased yield loads. Most shoot extension growth was completed during phase 1. More vigorous shoot growth took place during phase 2 for an 85% TAW level as compared to a 25% TAW level. Trunk growth was completed mainly at the end of phase 2 for the higher TAW levels (85% and 65%), b...