Breeding of eleven artificial mulberry hibrids by stimation of some parameters

Abstract

The main objective of this work was to evaluate the phenotypic and genetic variation of the yield of mulberry leaves and of some other important sericicultural traits, as well as to make comparisons of the potencial of selected hibrids with a widely used commercial variety, in the State of So Paulo. In addition, a critical study was made abouth the adequacy of the experimental design used, which is very common in our conditions. The following traits were considered: a) weight of leaves; b) weight of branches; c) length and with of leaves and dl length of petioles. The experiment was in a randomized complete block design, with four replications, four plants per plot and twelve treatments, namely: eleven previously selected hybrids and variety Calabresa as check. Data were collected from individual plants in three cuttings, with a three month interval. Moo, therefore, were split in time- The experiment was conducted in the Posto Experimental de Sericicultura, Limeira, Estado de São Paulo, and began in March, 1976. It could be verified that leave characters were less affected by environmental effects than yield of leaves. Therefore, in a breeding program developed to increase leaf area those characters are expected to give better response to selection the yield. Genotypic differences among hybrids could be detected, indicating that previous selection, to select the ones here studied, were not totally efficient. In relation to the check variety, the most promising hybrids were 13/6 and 19/13, ranking number 19/1 as the poorest. This kind of conclusions, however, was very weakened by the high coefficients of variation observed, mainly for yield. A significant treatments by cuttings interaction indicated that early selection, basal cri few number of cuttings, should not be recommended. It was concluded also that experimental precision of the selection unit can be partly improved by planning experiments with more replications and less plants per plot, for a given experimental area.