Abstract
Leucaena [Leucaena leucocephala (Lam.) de Wit] psyllid resistance was evaluated in three species (7 accessions) and eight hybrids of the genus Leucaena. The results indicated that the species L. pallida (K177 and K376) was most resistant to this psyllid. The widely-planted species L. leucocephala (K8) was found to be susceptible to the insects. The hybrids, L pallida x L diversifolia and L. leucocephala x L. pallida performed better than the other hybrids in terms of psyllid resistance, followed by L. diversifolia x L. leucocephala. The cross L. leucocephala x L. diversifolia, although less resistant, was high-yielding. These hybrids were consequently selected to intensively advanced generations for further study. Four generations of the hybrids were assessed. The results showed that the resistance of F1 plants was intermediate between their parents. From F2 plants to F4 plants, individuals with low damage rating increased, whereas individuals with high scores decreased from generation to generation. The laboratory observation of psyllid resistance in F3 plants and F4 plants was similar. Thus, it is possible to breed for psyllid-resistant leucaena through hybrid selection.
