紫外光B辐射对水稻生长和生长素水平影响的初步研究

EFFECTS OF ULTRAVIOLET-B RADIATION ON GROWTH AND IAA LEVEL OF RICE (ORYZA SATIVA L. )

2个水稻品种IR68和Dular生长在室外条件下，在以自然条件、13．0和19．1kJ·m－2．d－1（分别模拟臭氧浓度下降20％和40％时的UV－B强度）的紫外光B（UV－B280～320um）进行2和4wk的照射处理，以研究UV-B对水稻生长的影响．结果表明：UV-B强度增加能使2个水稻品种的株高、叶面积和叶m（DW）下降，而对分蘖数没有影响；随着UV-B处理强度的增加，IR68和Dular叶片IAA含量显著下降．在4wk处理的条件下．19．1kJ·m-2·d－1的UV-B使IR68和Dular叶片的IAA含量分别下降了48．7％和46．2％．值得注意的是．UV-B处理提高了2个水稻品种叶片内的IAA氧化酶的活性．初步推测UV-B使水稻叶片IAA氧化酶活性提高导致IAA含量的下降．从而抑制了水稻的生长．

Two rice cultivars IR68 and Dular were grown under outdoor conditions and treated by 13. 0 and 19. 1kJ. m-2. d-1 (stimulating 20% and 40% ozone depletion) of biologically effective ultraviolet - B (UV-B)for two and four weeks to study the effect of supplemental UV-B radiation on the growth of rice. The results showed that plant height, leaf area, leaf dry weight except tiller number of both cultivars were reduced by enhanced UV-B radiation. IAA contents in the leaves of IR68 and Dular were decreased dramatically with the increase of UV-B treatment dose. After four weeks treatment, the reduction rate of IAA content in the leaves of IR68 and Dular subjected to 19. 1 kJ·m-2·d-1 UV-B radiation reached 48. 7% and 46. 2%,respectively. It was necessary to point out that IAA oxidase activities in both cultivars were promoted by UV-B treatment. It was discussed that the promotion of IAA oxidase activity in ice leaf induced by UV-B radiation resulted in the destroy of IAA and in turn to cause the inhibition the growth of rice.