Acacia mearnsii (Fabaceae) reproductive biology:: pollen tube viability and growth

The low seed production in Acacia mearnsii De Wild. populations indicates that narrow genetic variability interferes with the reproduction. The viability of polyads of A. mearnsii trees front a seed production area was evaluated through in vitro germination and the calorimeter method. A high mean germination (73%) and low mean pollen tube growth (23%) were observed in the germplasm. Only tree 30 presented 60% germinated pollen tubes. The other means were less that] 50%. On the other hand, the viability observed by the colorimeter method was high (100% viable polyads in five trees), which indicated that the colorimeter technique overestimated the trite viability. This study showed that the germination ability of polyads was influenced by the genotype, contributing to a limited seed formation.