Interrelationship of yield and its morphological components in annual ryegrass

Abstract

The potential for genetic improvement of annual ryegrass (Lolium rigidum L.) yield through selection based on morphological factors such as leaf elongation rate has been suggested. Field experiments were conducted to study the relationship between forage yield and the morphological characters of the plants. The influence of using such characters in improving forage yield was also determined using one cycle of recurrent restricted phenotypic selection. Among plants a positive correlation (r = 0.64) existed between yield/tiller and leaf elongation rate, and negative correlation (r = - 0.53) existed between yield/tiller and rate of tillering. Path coefficient analysis showed that both yield/tiller and leaf elongation rate had large positive direct effects on total yield/plant. The direct effect of yield/tiller on yield/plant was about 2.1 times as great as the direct effect of number of tillers/plant. Using leaf elongation rate as selection criterion, and the recurrent restricted phenotypic selection procedures resulted in increasing forage yield of this grass 39% over that of the original population in the selection direction for high leaf elongation rate. The data suggest that leaf elongation rate can be an efficient selection criterion in improving forage productivity of this crop.