Variabilidade genética para caracteres morfométricos de matrizes de castanha-do-brasil da Amazônia Mato-grossense

Abstract

The goal of the study was to detect genetic variability in Brazilian nuts parent trees through parameters estimation and genetic gains for the following indexes: fruit weight (g) seed weight per fruit (g) and number of seeds per fruit at species pre-improvement. Ninety (90) open pollination parent trees were used, 30 of which being of each type, locally called "rajada", "mirim" and "rosa" at the Cotriguacu municipality, Northeastern of Mato Grosso State. A completely randomized design was used, with 90 treatments (parent trees) and six fruits per parcel with their respective seeds. Variables were analyzed using the method of mixed univariate additive linear model from the software SELEGEN-REML/BLUP. Individual heritability coefficients in the broad sense for total genotypic effects (0,21, 0,14 e 0,34) for fruit weight (g) seed weight per fruit (g) and number of seeds per fruit (g) respectively, are considered moderate for the two first indexes and high for number of seeds per fruit, suggesting substantial genetic control. Selection of the 10 best provenances and parent trees showed predominance of the "rosa" type, allowing substantial genetic gains of at least 24,16% for fruit weight (g), 27,44% for seed weight per fruit and 16,92% for the number of seeds per fruit. The remarkable values for the "rosa" type suggest utilization of such germoplasms in genetic improvement programs of this species in the following evaluations. The results also point out the possibility of obtaining intraspecific hybrids for desirable characteristics.