Heterosis and combining ability in a half diallel cross of kenaf ( Hibiscus cannabinus L.) in south Italy

Abstract

The occurrence of heterosis has been evaluated in 45 F 1 combinations derived from ten parental genotypes of kenaf ( Hibiscus cannabinus L.) according to a diallelic scheme. In addition studies have been conducted to assess the combining ability for yield components, using method 2, model I, of the Griffing diallel analysis. The characteristics analyzed were: plant height, basal diameter, fresh and dry weight of bark and core of the useable stalk portion. Dry bark/dry woody core weight was evaluated also. The highly significant F-test values demonstrated the existence of variability for general combining ability (GCA) and specific combining ability (SCA), and for all the characters analysed. Mean squares of GCA were always (except for basal diameter) higher than those of SCA. However, when compared in terms of the average squared effects (components), the effects of SCA were greater than those of GCA, indicating the importance of non-additive genetic effects in determining the expression of yield components. Lines HC 625, HC 622 and HC 602 were the best general combiners for the most important characters. Heterosis for dry bark weight was highest in HC 602×HC 726.