Morphology, pollen viability, and meiotic index of nance (Byrsonima cydoniifolia [A.] Juss)

Byrsonima cydoniifolia (nance), a forest species from the Malpighiaceae family, is widely distributed across Brazil, predominantly in the North, Northeast, and Central-West regions. This study aimed to analyze pollen morphology, viability, and the meiotic index in different native populations of nance in the eastern region of Mato Grosso state. For each population, five individuals were selected, and floral buds were collected during various developmental stages. The morphological characterization of pollen grains was conducted using the acetolysis protocol, followed by photography, measurement, and classification based on size, shape, ornamentation, and polar area index. The meiotic index was determined by counting post-meiotic products. Pollen grains were found to be spheroidal, small, 3-colporate, with a colpus, identified as tricolporate grains with a large polar area. The exine in the polar area was microreticulate. The meiotic index varied among populations and individuals, exceeding 95%. Pollen viability tests effectively distinguished between viable and non-viable pollen, with viability rates over 90%. The pollen grains contained starch and lipids as reserve substances. The species demonstrated high stability and meiotic regularity. The findings from this study contribute to our understanding of the ecology, conservation, dispersal, and propagation potential of nance, which supports the reproductive success of the species.