INFLUENCE OF FRUIT SPACING ON FRUIT-QUALITY AND MINERAL PARTITIONING OF REDCHIEF DELICIOUS APPLE UNDER FULL CROP CONDITIONS

Yield, fruit quality, and mineral partitioning in fruit and leaf tissu es of 'Redchief Delicious' apple (Malus domestica Borkh.) on M.9/MM.10 6 and M.9/MM.111 with five levels of fruit spacing (thinning) at harve st and after six months of storage were studied under full crop condit ions. Fruit weight in the trees thinned at 18 cm spacing was higher, b ut yield was lower than those of both 5 and 10 cm spacings. Trees thin ned at 36 cm spacing had a higher return bloom and yield in the follow ing year. Fruit spacing greater than 10 cm increased fruit color and s oluble solids concentration (SSC) both at harvest and after storage. F ruit firmness at harvest was not affected by fruit spacing, but fruit from 18 and 25 cm spacings had significantly lower firmness than all o ther spacings after storage. Fruit spacing greater than 10 cm decrease d N but increased K expressed at mg K/100g fresh weight in both leaf a nd fruit tissues. Trees thinned at 5 and 10 cm spacings had similar le vels of fruit Ca, and both had significantly higher fruit Ca than thos e thinned at 18, 25 and 36 cm spacings. All quality and mineral compos ition factors considered, thinning fruit to a 10 to 18 cm spacing is b eneficial, depending an the market demands and objectives of productio n. Thinning at distances greater than 18 cm between fruit is not advis able, as yield was drastically reduced without gaining additional frui t color or firmness. 'Redchief Delicious' trees on M.9/MM.106 had a hi gher yield, but lighter fruit color and lower SSC than those on M.9/MM .111, although fruit on both interstock/rootstock combinations had sim ilar weights. Fruit from trees on M.9/MM.106 had higher Cu, Mn and Mg than those on M.9/MM.111.