Fenologia reprodutiva, polinização e reprodução de Dipteryx alata Vogel (Leguminosae-Papilionoideae) em Mato Grosso do Sul, Brasil

Abstract

The reproductive biology of Dipteryx alata was studied from September/2004 through August/2006. Dipteryx alata is a tree that blooms during the rainy season (4-6 months) and fructification peak occurs in the dry season. There are annual variations in the intensity of flowering and fructification. The flowers are zygomorphic, papilionaceous, hermaphrodite, relatively small, odoriferous, diurnal and last up to 10 hours. The calyx has two petaloid lobules and the corolla is formed by the standard, wings and the petals of the keel. Pollen viability is 94.4%. The stigma is covered by a pelicule that prevents pollen adherence and limits the spontaneous self-pollination. Nectar is produced in a chamber, in small quantity (1.45 µL) and with concentration of 25%. Dipteryx alata has keel flowers and the mechanism of pollination is intermediate between the explosive and valvular types. This species is alogamous, has late acting self-incompatibility and high rate of abortion (ER = 0.45). The main pollinator is Xylocopa suspecta (16.6% of visits), which visits legitimately the flowers and presents trap lining behavior, that promotes pollen flow between plants. Although the visitation rate of Pseudaugochlora graminea (15.3%) and Apis mellifera (39.5%) bees are relatively high, they are not good pollinators (pollination efficiency = 3.5 and 0, respectively), because they generally did not accomplish movement between plants. Apis mellifera robbed nectar in 45.5% of visits. The increasing of seed production in natural populations of D. alata depends on the maintenance of effective pollinators (solitary bees), and it is recommended the management of A. mellifera.