UV-B辐射对植物花粉萌发率和花粉管生长的累积效应

研究了19种植物花粉在不同UV－B辐射强度和辐照时间下其萌发率和花粉管伸长的变化，结果表明，UV－B辐射增加显著抑制大多数植物花粉的萌发率和花粉管生长；与对照相比，较高强度的UV－B对花粉的抑制作用大于较低强度；几个种的花粉萌发率及花粉管生长对UV－B增强不敏感，甚至被UV－B辐射所促进；辐射时间越长，对花粉抑制作用愈大，说明具有辐射累积效应，由此可知，植物花粉的萌发过程对UV－B的敏感性变化在自然条件下将会产生严重的生态学后果。

Cumulative effect of solar ultraviolet-B radiation on pollen germination and tube growth of 19 species in vitro

In order to determine the response of pollen to UV-B irradiation and the cumulative effects of UV-B exposure time on pollen germination and tube growth of plants, 19 species were investigated in vitro by exposing their pollen grains to two levels of enhanced ultravioet-B(UV-BBE) (280-320 nm, 350 and 500 mW/m2 biologically effective UV-B radiation), simulating 8% and 21% stratospheric ozone depletion in Lanzhou, China (36.04 degrees N, 1550 m), and to no UV-B (control group). Compared with the control, enhanced UV-B radiation significantly inhibited pollen germination and tube growth in most species. Higher UV-B flux rate caused greater inhibitory effect than lower UV-B radiation level. Several test plants exhibited insensitivity, even stimulation of pollen germination and tube growth to UV-B. The reduction in pollen germination rate and tube growth increased with exposure time, which indicated a cumulative effect of UV-B radiation. It is concluded that changes in pollen susceptibility to UV-B would have a serious ecological consequence under natural conditions.