Influence of Fruit Spacing on Fruit Quality and Mineral Partitioning of ‘Redchief Delicious’ Apple Under Full Crop Conditions

Abstract

Yield, fruit quality, and mineral partitioning in fruit and leaf tissues of ‘Redchief Delicious’ apple ( Malus domesticaBorkh.) on M.9/MM.106 and M.9/MM.111 with five levels of fruit spacing (thinning) at harvest and after six months of storage were studied under full crop conditions. Fruit weight in the trees thinned at 18 cm spacing was higher, but yield was lower than those of both 5 and 10 cm spacings. Trees thinned at 36 cm spacing had a higher return bloom and yield in the following year. Fruit spacing greater than 10 cm increased fruit color and soluble solids concentration (SSC) both at harvest and after storage. Fruit firmness at harvest was not affected by fruit spacing, but fruit from 18 and 25 cm spacings had significantly lower firmness than all other spacings after storage. Fruit spacing greater than 10 cm decreased N but increased K expressed at mg K/100g fresh weight in both leaf and fruit tissues. Trees thinned at 5 and 10 cm spacings had similar levels of fruit Ca, and both had significantly higher fruit Ca than those thinned at 18, 25 and 36 cm spacings. All quality and mineral composition factors considered, thinning fruit to a 10 to 18 cm spacing is beneficial, depending an the market demands and objectives of production. Thinning at distances greater than 18 cm between fruit is not advisable, as yield was drastically reduced without gaining additional fruit color or firmness. ‘Redchief Delicious’ trees on M.9/MM.106 had a higher yield, but lighter fruit color and lower SSC than those on M.9/MM.111, although fruit on both interstock/rootstock combinations had similar weights. Fruit from trees on M.9/MM.106 had higher Cu, Mn and Mg than those on M.9/MM.111.