Effects of Ca²⁺ on in vitro pollen germination of three Acacia species

We investigated the effects of Ca²⁺ on in vitro pollen germination of Acacia auriculiformis, Acacia mangium, and Acacia crassicarpa under different concentrations of Ca²⁺ (50 mg.L⁻¹, 100 mg.L⁻¹, 150 mg.L⁻¹, 200 mg.L⁻¹, 250 mg.L⁻¹, 300 mg.L⁻¹, 350 mg.L⁻¹ and 400 mg.L⁻¹) in the present study. Our results revealed that Ca²⁺ could stimulate the pollen germination percentage and the pollen tube growth of A. auficuliformis and A. crassicarpa under a certain concentration. In vitro pollen germination of A. mangium did not require exogenous Ca²⁺. With high Ca²⁺ concentration, the pollen germination of A. auriculiformis, A. mangium, and A. crassicarpa were obviously inhibited. With the rise of Ca²⁺ concentration, the percentage of pollen germination, the pollen tube length, the pollen tube growth, and the number of pollen tube were increased. However, the pollen germination percentage decreased with high Ca²⁺ concentration.