In vitro germination and pollen tube growth of maize (Zea mays) pollen. II. Pollen source, calcium, and boron interactions

摘要

Pollen grains from six single cross hybrids (Wf9ensp;times;ensp;H55, Wf9ensp;times;ensp;H50, H49ensp;times;ensp;H55, H49ensp;times;ensp;H50, Ky49ensp;times;ensp;Ky27, and K64ensp;times;ensp;K55) ofZea maysL. were cultured on an artificial medium containing 15 sucrose and 0.6 bacto-agar supplemented with all possible combinations of two levels (0.00 and 0.03) of calcium nitrate (Ca) and two levels (0.00 and 0.01) of boric acid (B). The effect of Ca and B on germination percentage was found to be dependent on the genetic source of the pollen. At the 0.00 levels of Ca and B, the germination percentage of the hybrids ranged from 26.6 for Ky49ensp;times;ensp;Ky27 to 58.1 for K64ensp;times;ensp;K55. With either Ky49ensp;times;ensp;Ky27 or K64ensp;times;ensp;K55 pollen, the addition of Ca and B to the medium resulted in a lower germination percentage whereas the addition of Ca and B increased the germination percentage of the other hybrids. The addition of B in the absence of Ca sharply reduced the germination percentage in all hybrids while in the presence of Ca, the effect of B varied with the hybrid involved. For pollen tube length, highly significant interactions between hybrids and levels of Ca and B were found. However, maximum pollen tube lengths were obtained for all hybrids with both Ca and B in the medium. The addition of B in the absence of Ca reduced the pollen tube length of all hybrids whereas the addition of B in the presence of Ca increased pollen tube length. In general, the addition of both Ca and B increased the rate of pollen tube growth especially in the period 2 to 3 hours after inoculation.