New arboreal Leucaena leucocephala accessions.
Trials are reported of 40 'giant' provenances of L. leucocephala previously identified at the Waimanalo Research Station, Hawaii. The trees were planted at 1×1 m spacing in Apr. 1983 and ht. and d.b.h. measured periodically over 48 months. The rainfall was unusually low during this period. Growth in the first year was about half that normally recorded, but growth data at 15 month old showed only 6 provenances to be slightly above average in performance, suggesting no major variation in drought tolerance. Psyllid [Heteropsylla cubana] attack occurred late in 1984, and some provenances showed high susceptibility immediately. There was no growth in 1985 (apparently due to the combined effects of drought and psyllids). Psyllid tolerance was best in K584 and K636, but neither of these provenances was resistant. Some other provenances also showed higher psyllid tolerance, and some trees with high tolerances segregated from various other less tolerant provenances. Mean ht. at 48 month old (in 1987) was 5.1 m (about half the normal growth) with a range of 3.15 to 7.16 m, and with psyllid tolerant provenances averaging 7.0 m; psyllid populations had fallen by this time. The results suggest that these giant provenances have only a low genetic variation.