Predictions of GCA Model Estimates of Total Leaf Area and Leaf Area Distribution from Leaf Area of Parental Inbreds1

Abstract

The relationships of GCA (general combining ability) for total leaf area per plant and leaf area at leaf positions somewhat distal to the ear leaf to parental total leaf area per plant and leaf area at individual leaf positions were investigated by means of multiple regression procedures applied to data obtained from 10 homozygous inbred lines of corn (Zea mays L.) and the diallel set of crosses among them. In the multiple regression analyses, GCA model estimates of leaf area at leaf positions —4 and 6 (the fourth leaf position below and sixth leaf position above the ear, respectively) and total leaf area were used as dependent variables, while midparent values of leaf area at individual leaf positions and total leaf area were used as independent variables. The regression equations were then appraised for their ability to predict F1 leaf area, based on a GCA effects model, from midparent leaf area values.The results indicated: 1) GCA model estimates of total leaf area could readily have been predicted from midparent total leaf area; 2) GCA model estimates of leaf area at leaf position 6 could have been predicted by a linear function of midparent observations of total leaf area, leaf area at the upper leaf positions, and leaf area at leaf positions near the ear; and 3) GCA model estimates of leaf area at position —4 could have been predicted by a linear function of midparent values including leaf area at and below the ear leaf. However, since GCA model estimates of leaf area at leaf position —4 were poorly and mostly negatively correlated with parental leaf area, prediction of F1 leaf area at the lower leaf positions might generally be tenuous.