高原地区太阳UV-B增加对燕麦有效光合叶面积及灌浆的影响研究

Effects of Enhanced Solar UV-B Radiation on the Effective Photosynthetic Leaf Area and Milking Phase of Oat under Natural Field Condition in Qing Tibetan Plateau

由于大气的污染造成大气层臭氧层变薄,从而导致来自太阳紫外线-B辐射量增加,青藏高原UV-B增加量为全球第二,主要集中在6～9月份,正是植物生长、繁殖期,因此对植物可能产生一些负面影响。试验在大田条件下通过采用人工UV-B灯管模拟来增加太阳光辐射量5%和10%,进行对燕麦(Avenasativa)叶片衰老及灌浆期处理研究。结果表明:UV-B强度增加对有效光合面积和叶绿素含量下降的速率并无显著的影响,也未出现提前结束灌浆及早衰的趋势。表明在大田群体条件下,UV-B增加并未显著加速灌浆期燕麦的衰老过程。换言之,在青藏高原上来自太阳紫外辐射量的增加不会造成对草地显著影响。

Stratospheric ozone depletion occurs mainly over polar regions during the spring when the solar ultraviolet B-band （280-315 nm, UV-B） radiation is most intense in a year,but over the Qing Tibetan Plateau region, the intensity is highest from June to September when the amount of UV-B radiation reaching the regions is more than that in the adjacent areas lying in the same latitude by 10%. From June to September is just the time of plant＇s germination, development, and reproduction in the alpine region. The enhanced UV-B radiation may alter the rate of senescence in the forage plant, oats （Arena sativa ）, which plays the vital role in developing indigenous herdsman＇s animal husbandry industry. In the trial the authors enhanced the UV-B radiation by using lamp bank of florescent lights to increase the ambient levels of UV-B radiation in the field, we treated 3 groups under nature solar radiation, solar＋0. 50 W · m^2 , and solar＋1. 00 W · m^2 respectively, and surveyed the rate of senescence by measuring the rate of lessening in the effective photosynthetic leaf area, the concentration of the chlorophyll, and the milking phase of oat phenology. The results proved that the effect of the enhanced UV-B radiation on the rate of senescence of oats is caused by reducing the effective photosynthetic leaf area per plant by 21.5%, accelerating the rate of the loss of the chlorophyll compared with that of the controlled by an average of 7. 6 % and shortening the milking phase by an average of 2 days in the treated groups compared with the rate in the controlled, but there were not statistically significant differences from those of the non- treated group in these index of oaths senescence. All the results evidenced that the enhanced solar UV-B radiation has no significantly ominous consequence on the oat ecological characteristics concerning annual plant reproduction in Qing Tibetan plateau.