Vegetative Growth and Mixed-Bud Development of ‘Fuji’ Apple Trees as Influenced by Rootstocks and Microsprinkler Fertigation

Abstract

The influence of five rootstocks, B.9, M.9 NAKBT337, O.3, M.26 EMLA, and M.7 EMLA, and five nutrition treatments applied through a microsprinkler system, on growth characteristics of ‘BC-2 Fuji’ apple trees ( Malus domesticaBorkh.) was evaluated for two years. Nutrition treatments consisted of 22.4 kg nitrogen (N)/ha (low N), 89.7 kg N/ha (medium N), 156.9 kg N/ha (high N), 89.7 kg N/ha in combination with 78.5 kg potassium (K)/ha, and 156.9 kg N/ha in combination with 78.5 kg K/ha. Trees on M.7 EMLA had larger trunk cross-sectional areas (TCA) and longer limbs and terminal shoots than those on other rootstocks. Trees on B.9 had the smallest TCA and the shortest limbs and terminal shoot. The density of non-flowering spurs in the scion trees increased with the vigor of rootstocks. Trees on B.9 had significantly higher density of fruit spur without bourse shoot than those on other rootstocks in 1998. Bud break in the mixed-buds of trees on of M.7 EMLA was slower than those on B.9 and O.3 in both years. Over all, trees on B.9, M.9 and O.3 were less vigorous than those on M.7 EMLA and can be used for high-density orchards. Trees receiving high N had significantly longer terminal shoot than those with low N treatment in both years. Nutrition treatments showed little effect on other growth characteristics of scion trees.