Pollen morphology and availability of pollen and stigma in Syzygium (Myrtaceae)

Abstract The present study aimed to describe the pollen morphology in three species of Syzygium, to test pollen availability and stigma receptivity. The pollen was analyzed by light and scanning microscopy to show the detailed ornamentation of the pollen grains. Pollen availability was measured according to two protocols. Stigmatic receptivity was tested at different stages of flower development. There are differences among the pollen morphology for the species studied; when the polar and equatorial diameters are measured in the equatorial view of the pollen grains, it is observed that S. jambos is the largest species concerning the two values of the diameters, S. malaccense is the smallest species and S. aqueum, the largest species in relation to the polar diameter in the equatorial view. For the equatorial diameter in equatorial view, S. aqueum showed the smallest diameters and S. malaccense, the major diameters, but the two species overlap in the values of the measured diameters. There are variations in the number of apertures in the pollen grains. Alexander’s stain is more sensitive to estimate pollen availability and the species S. aqueum and S. jambos have the same schedules of pollen availability and stigma receptivity.

摘要 本研究旨在描述3种蒲桃属（Syzygium）植物的花粉形态，并检测花粉可利用性与柱头可授性。研究通过光学显微镜与扫描显微术对花粉粒的精细纹饰特征进行分析。花粉可利用性依据两套实验方案进行测定，柱头可授性则在花发育的不同阶段开展检测。所研究的三个物种的花粉形态存在差异：以花粉粒赤道面观测的极轴与赤道轴直径为指标时，就两项直径参数而言，洋蒲桃（S. jambos）的数值均为最大，马来蒲桃（S. malaccense）为最小；而水翁蒲桃（S. aqueum）在赤道面观测下的极轴直径为最大。而就赤道面观测的赤道轴直径而言，水翁蒲桃的直径最小，马来蒲桃的直径最大，但二者的测定直径存在重叠区间。不同物种的花粉粒萌发孔数量存在变异。亚历山大染色液（Alexander’s stain）在评估花粉可利用性时灵敏度更高，水翁蒲桃与洋蒲桃的花粉可利用性与柱头可授性节律完全一致。