Leucaena diversifolia and its hybrids for the highlands.

Abstract

Data published earlier on 24-month-old heights of Leucaena leucocephala K8 and L. diversifolia K156 at sites in Hawaii and the Philippines with mean annual temperatures between 19.4 and 28.1°C, are used to demonstrate that height growth is substantially reduced as av. temperatures fall. Regression coeff. of 0.533 m/yr per °C for L. leucocephala and 0.326 m/yr per °C for L. diversifolia are calculated. Since L. diversifolia ('red leucaena') is more cold tolerant than L. leucocephala a trial was undertaken to evaluate the growth and psyllid [Heteropsylla cubana] tolerance of several highland tetraploid accessions of L. diversifolia and its hybrids, in comparison with varieties of L. leucocephala and L. pallida, at a site on the island of Hawaii. The site has an av. ambient temp. of 16.6°C, and av. soil temp. of 14.4°C. The tallest plots at 10.5 month old consisted of 5 plots of L. diversifolia or its hybrids and a cross of L. pallida (K376, also a highland tetraploid) with L. leucocephala K8. Psyllid tolerance of these varieties/hybrids was also good. Most varieties of L. leucocephala tested performed poorly and were less psyllid tolerant. The use of the best performance varieties in kikuyu grass [Pennisetum clandestinum] pastures is suggested.