The components of variation in an intervarietal cross in Leucaena leucocephala (Lam.) de wit

Abstract

An intervarietal cross in Leucaena leucocephala between the contrasting varieties Bald Hills and Guatemala was studied in an experiment incorporating .the two parental varieties, an F2 population, and 37 F3 families. Characters examined were length of main stem and stem number. Phenotypic variances for the F2 population were low in relation to the estimated non-genetic variance. In length of main stem 3 months after planting, genetic variance accounted for 21.9% of the total variance, and partition of variation showed the presence of strong non-genetic and additive genetic components, and absence of any non-additive genetic component. In length of main stem at the end of the season and in stem number, no genetic variance could be demonstrated. Polysomic inheritance is suggested as an explanation of this restricted segregation. Differences between F3 family means were highly significant in each of the characters measured. Length of main stem and stem number were highly correlated (r = 0.5 and 0.7), which suggests that these characters are not inherited independently but are both related to plant vigour. Applications to plant breeding are discussed.