Effects of Water and Nutrient Application Frequency on Yield, Root Growth and Water Usage by 'Brookfield Gala' Apple Trees

摘要

Effects of water and nutrient application frequencies on fruit yield, root growth and water usage were studied in a 'Brookfield Gala' apple orchard in Greyton, South Africa. Two irrigation systems, micro sprinkler and drip, were used to apply water atthree different frequencies. In the micro sprinkler treatment, nutrients were applied manually. In the drip treatments water containing nutrients was applied once or twice a day (daily), or several times each day (pulsed). In all cases the nutrient supply per tree, per phonological stage, was the same. Fruit yields were determined at harvest in 2005/06 (third leaf), 2006/07 (fourth leaf) and 2007/08 (fifth leaf). Root studies were carried out after harvest in 2007/8. Daily and pulsed drip irrigation promoted significantly higher yields, increased the proportions of thin (< 3 mm diameter) to thick (> 3 mm) roots, and used 35% less water than micro sprinkler irrigation.