GENETIC PARAMETERS AND EFFICIENCY OF EARLY SELECTION ON Pinus ayacahuite EHREN. VAR. ayacahuite

Abstract

To evaluate the efficiency of early selection in Pinus ayacahuite Ehren. var. ayacahuite, genetic control and age-age genetic correlations for total height and diameter at ground level were assessed on trees at ages 3 to 13 years. Populations from southern Mexico and from Central America, with a total of 42 open-pollinated families were included in this trial. Both traits showed broad genetic variation between groups of populations and among families within groups. Individual-tree heritability for height and ground-leves diameter ranged from 0.31 to 0.54, whereas family heritability ranged from 0.71 to 0.83, both increasing with age. At age 13, height and diameter showed a strong genetic correlation (r_Gxy = 0.90), so that any of them could be used as selection criterion for growth. Age-age correlations for both traits were high and increased with age (they ranged from 0.72 to 0.78 for height and 0.75 to 0.85 for diameter at ground level). These results suggest that early selection (at 3 years of age) would be about 60 % as efficient as the response from direct selection at age 13.