Water application for optimum yield, quality, and mineral partitioning in apples under different irrigation systems

In a long-term study, use of crop evapotranspiration (ETc), when a precise crop coefficient (Kc), ground shading, and canopy maturity were used, a reliable tool for determination of water requirement for 'Fuji' apples was achieved. Each tree during a growing season received 5617 to 6461 L in full sprinkler (FS) and 2921 to 3996 L in full drip (FD) systems during the first 4-year cycle of 2004-2007. Using a partial root zone-drying regime through a micro sprinkler system (PRS) reduced fruit size but improved fruit color. Trees with FS and FD had higher yield and fruit weight than those with other irrigation treatments during the 2008-2011 period. During this period, trees in both FS and FD treatments had about 14% more cumulative yield, resulting in about 14% less fruit weight as compared to the first 4-year period. Over 2008-2011, fruits from trees with a FD system had better color than those with FS and 65% drip (65% D) systems. Trees with FS and FD systems had the softest but those with 50% sprinkler (50% S) had the firmest fruit. Fruits with 50% drip (50% D) and 65% D had the highest starch degradation pattern (SDP). Skin russet in the fruits from trees with FS and FD treatments was higher but sunburn was lower than those on other treatments during 2008-2011. Fruit from trees receiving 40 g N tree(-1) had better fruit color than those receiving 80 g N tree(-1).