| Seventeen studies in four subject areas were described, the first and major one being interspecific hybridization. Fully 98% (118/120) of all possible combinations in a 16 x 16 diallel among fifteen Leucaena species were tested with hand pollinations of 49,157 florets. Ninety-one (76%) matings produced seed. Polyploidy in Leucaena probably buffers hybridization in interploidal (74%) and intra-tetraploid matings (100%).;The second area was botanic (morphological studies of leaves and pollen, and seed production and tree growth). Leaf morphology (pinnule length, width, pinnules per pinna, pinnae per leaf) of hybrids was geometrically intermediate between parents, sensitive to chromosome dosage, and probably controlled by developmental genes that control the number of cell division cycles. Pollen stainability in hybrids ranged widely (1 to 100%). Fifty-two hybrids flowered and 24 remained essentially seedless, of which 14 were triploid.;The third area was agronomic (genetic inheritance, resistance to psyllid insects, seedling vigor, and forage digestibility). In L. lanceolata, green pinnule color was incompletely dominant to red and probably controlled by one locus. Narrow branch angle was partially recessive to wide angle and probably controlled by two loci in L. lanceolata. Psyllid resistance was not strictly related to pinnule size in F;The fourth area was technological innovation. This included floral and pod bagging, seed cleaning, pollen storage and irradiation, and selection of inflorescences for meiotic analysis. |
