Effect of Boron on Pollen Attributes in Different Cultivars of Malus domestica L.

The effect of varying boron concentrations on in vivo pollen germination and tube penetration in four different apple cultivar crosses among ‘Golden Delicious,’ ‘Red Delicious,’ ‘Gala’ and ‘Fuji’ was evaluated. Boric acid (H3BO3) with two different concentrations: 1000 and 2000 mg L−1, was sprayed on the foliage long before the onset of flowering. Pollen–pistil interaction vis-a-vis pollen germination and tube penetration was evaluated using fluorescence microscopy technique, 72 and 120 h after manual pollination. Among different crosses, ♀Golden delicious × Red delicious♂ treated at 1000 mg L−1 concentration of boric acid showed maximum (27.39%) pollen germination and pollen tubes at different levels inside the style. In control without boron, only 6.49% germination was observed. Interaction of boron conc. × time depicted maximum pollen germination and tube number 120 hap. The present study demonstrates that foliar application of boron beyond 1000 mg L−1 on different apple cultivars reduces germination of pollen and development of pollen tubes down the style.