Seedling-selection effects on morphological traits of mature plants in red clover.

Knowledge of the correlation between juvenileand mature-plant traits is critical in determining the opportunities for early stage selection. The effects of early stage selection on mature-plant performance have rarely been quantified. This study was conducted to identify seedling traints in red clover (Trifolium pratense L.) that correlate to mature-plant traits and to evaluate the effect of seedling selection on forage yields and other mature-plant traits. The results showed that relationships between most seedlingand mature-plant traits were weak (r ranged from 0.170 to 0.239). Nevertheless, selecting the top 10% seedlings for petiole length, days from emergence to full expansion of the 4th leaf (D4LE), or leaves per seedling, produced a mature-plant population with higher individual plant dry weight (IPDW1) and higher annual yield in 1993 (Y93). Selection for leaves per seedling increased IPDW1 by 23.2%. Selection for petiole length and the smallest D4LE increased Y93 by 15.7% and 13.8%, respectively. Furthermore, substantial expected genetic gains were obtained for IPDW1 and Y93 when selecting for some seedling traits. We conclude that plants and families with low potential yield can be eliminated at the seedling stage in red clover. This will allow breeders to increase the number of superior plants to be field tested or to conduct a more rigorous evaluation of the selected plants. Among the five selection schemes tested for direct selection of mature-plant traits, mass selection produced the largest genetic gain.