A retrospective early test of Pinus sylvestris seedlings grown at wide anddense spacing

Stored seeds from 30 open-pollinated families that had been field tested fo r 28 years provided a retrospective opportunity to assess the efficiency of early testing in Scots pine (Pinus sylvestris L.). Seedlings height at the end of first (HGP1), second (HGP2) and third growth period (HGP3), and in the third growth period, leader length (LEADER3), basal stem diameter (DIA3 ), number of stem units (NSU3), mean stem unit length (MSUL3), aboveground fresh weight (AGFWT3), stem dry weight (STDWT3), and shoot and needle dry w eight (SHNDWT3) were studied under wide and dense spacing. Families differe d at the 1 or 0.1% level of probability. Differences between spacing were s ignificant at the 0.01% level of probability for all traits measured in the third growth period. Families interacted significantly with spacing for HG P2, HGP3, LEADER3, AGFWT3, SHNDWT3 and MSUL3. Interactions were due to rank changes and the interaction component of variance varied from 26 to 96% of the family variance. Estimates of h(i)(2) over wide and dense spacing rang ed between 0.23 +/- 0.11 (HGP2) and 0.51 +/- 0.14 (NSU3). Spacing did not a lter the variance structure, h(i)(2) for each trait under wide or dense spa cing were similar. However, spacing affected the phytotron-field genetic co rrelations. The average of 80 genetic correlation estimates was 0.52 under wide spacing and 0.29 under dense spacing. Averaged over eight field traits , the efficiency of indirect juvenile selection for the field traits indire ct-direct selection percentage ranged from -15% for NSU3 under dense spacin g to 99% for HGP3 under wide spacing.