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Vegetative growth and fruit characteristics were monitored for two years after pruning the roots of 13year-old Seibel 9110 grapes (Vitis spp.). Roots were pruned on March 1, 1990, on two sides at 15, 30, 60, and 90 ㎝ from the trunk and to a depth of 30 ㎝. Shoot length, the amount of pruned canes, and dry weight of the excavated vines were reduced in proportion to the severity of root pruning. The effect of root pruning at 60 and 90 ㎝ was not significantly different from that of the controls. The amount of pruned canes and dry weight of a vine were about one-third and one-half of the controls, respectively, when root-pruned at 15 ㎝. Trunk circumference, trunk cross-sectional area, and trunk dry weight were not affected by pruning seventies. Concentrations of leaf K and Mn declined as the severity of root pruning increased. The weight of fruit clusters and the yield per vine were severely affected when root-pruned at 15 ㎝. Root pruning did not affect the concentrations of total soluble solids. The severer the degree of root pruning, the lower the concentrations of N in the roots and the trunk. Concentrations of other elements were not significantly altered and, when the changes were significant, they were not related with the pruning severity. Root pruning at 15 em reduced the contents of carbohydrates and N of the shoots to one-eighth and one-sixth of the controls, respectively. The aerial parts of a vine contained more carbohydrates, K and Ca than the roots. About twice as much N was found in the roots than in aerial parts. As the severity of root pruning increased, K and Ca increased in the aerial parts of a vine. Pruning the roots the previous year at 15 ㎝ reduced the increase in trunk circumference, the weight of clusters, and the yield. However, no carry-over effect of root pruning was apparent when pruned at 60 or 90 ㎝. It was concluded that root pruning at a 60 ㎝ distance on two sides of the trunk and to a depth of 30 ㎝ was effective in controlling vegetative growth without affecting either the yield or fruit quality.
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