The breeding system of Inga edulis Mart. and Inga stipularis D.C. was studied in an area of forest, located in the UFAM Experimental Farm, Manaus, AM, from November/2006 to November/2007. The results showed that both species do not set fruit from self-pollination and that the percentage of fruit set proceeding from cross-pollination in I. edulis (5%) and I. stipularis (21%) is superior to the natural pollination (control), 1% and 7%, respectively. The analyses of pollen tube, originating from self-pollination and cross-pollination, reveal that a small fraction reaches the ovules of I. edulis after 8 and 12 hours, and in I. stipularis 24 hours after pollinations. In addition there is a greater percentile of tubes penetrating in the ovules of I. edulis. The arrival speed of the tubes in the ovules deriving from self-pollination and cross-pollination is similar in both species. The low indices of fruit set in I. edulis and I. stipularis probably is a result from the raised index of geitonogamy promoted by the pollinators and the late-acting self-incompatibility.
Inga; pollen tube; late-acting self-incompatibility; Amazon rain forest
