TREND OF WITHIN FAMILY-PLOT SELECTION PRACTISED IN THREE SEEDLING SEED ORCHARDS OF <em>EUCALYPTUS</em> <em>PELLLTA</em> IN INDONESIA

Abstract

LEKSONO, B. & KURINOBU, S. 2005. Trend of within family-plot selection practised
in three seedling seed orchards of Eucalyptus pellita in Indonesia. A trend of within
family-plot selection was examined by applying a retrospective selection index to the
result of the selection in three seedling seed orchards of Eucalyptus pellita in South
Sumatra, Indonesia. The orchards were established in randomised complete block
designs with five-tree row plot. Within family-plot selections were conducted twice
with selection intensities of around 40% at the first selection (36 months after planting) and 50% at the second selection (58 months). The results were analysed with the retrospective selection index using data on height, diameter and stem form measured before each selection. In terms of standardized index weight, diameter was found to be the highest priority trait throughout the two stages of selection in all the orchards. Height was considered as a second priority trait at the first within family-plot selection, whereas relative priority of stem form was increased at the second selection. Expected gains from within family-plot selection were positive for all of the traits in both selection stages and mean cumulative gains were 2.7% for height, 3.9% for diameter and 1.7% for stem form.