Sele??o de matrizes e tipo de propágulo na enxertia de substitui??o de copa em Ilex paraguariensis

摘要

The objective of this research was to evaluate the technique of topgrafting in Ilex paraguariensis. For that reason, the influence of the position of the graft in the stock plant, the age and the stock plant, as well as, the definition of the best time for grafting evaluation and vigor of the grafts were evaluated. 13 years old trees located in Colombo - PR were submitted to the cut at 10 cm above the soil for sprouts induction, on which the grafting was accomplished by top cleft grafting. The grafts were collected from 10 year-old mother trees and from seven trees older than 80 years. From the selected trees grafts were taken from the top, medium and basal position inside the mother tree. The experiment was installed with three replications and 42 treatments, in a hierarchical factorial design 2 x 7 x 3 (two ages, seven mother trees for each age and three collection positions). The variables of interest were percentage of survival and number and length of sprouts. A differentiated performance of the mother trees when in different collection positions was observed. The individual heritability of the genotipic effects, estimated for the survival of the grafts, was superior to 74%, for all the evaluation periods, which is considered very high. The coefficient of genetic variation was 34%, for the observed periods same or superior to 90 days, indicating good genetic gain perspectives for the improvement of the genetic material. The coefficients of experimental variation, obtained for that same periods were between 78% and 94%. It can be observed that there were no differences among the genetic parameters indicating the possibility of evaluation of the survival of the grafts after 90 days. Based on those results it can be concluded that the Ilex paraguariensis topgrafting directly in the field is technically viable; better survival of grafting are obtained for young trees and with apical sprouts; mother trees have shown differentiated responses in respect to survival of grafting.