Growth, leaf mineral nutrition, and leaf water status of mature apple trees subjected to various crop loads and soil water conditions
1989
Erf, J.A. | Proctor, J.T.A.
Mature fruiting and defruited 'McIntosh'/M.26 apple (Malus domestica Borkh.) trees were exposed to natural rainfall or to no rainfall with the use of under-canopy tent-like covers. With covers present, fruit diameter tended to be less and, on one occasion, soluble solids concentration and fruit firmness increased. Trunk growth was reduced more by fruit than by covers. Trunk growth of fruiting trees did not respond to covers, whereas trunk growth of defruited trees was reduced by covers. Fruit load and reduced soil water content did not affect terminal shoot length. In one experiment, specific leaf weight (SLW) was less for fruiting trees than for defruited trees. Fruiting increased foliar N, P, Ca, and Mg and decreased K concentration. On a leaf-area basis, K was again lower in cropping trees while other nutrients remained mostly unchanged. With tent covers, trees generally had less foliar N, P, and K based on either concentration or amount per unit of leaf area. Leaf water potential was lower for trees with fruit and tended to be lower for trees with tent covers. Leaf stomatal conductance was higher for fruiting trees than for defruited trees and higher for trees without tent covers than for trees with tent covers.
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