水稻种子低温萌发生理机制的初步研究

 以粳稻品种USSR5、Hatanishiki和籼稻品种密阳23、N22为材料，研究了水稻品种间种子低温发芽力的差异，并进一步从内源植物激素含量、种子对激素的敏感性及淀粉酶等方面对耐低温发芽的机理进行探讨。结果表明，来自前苏联的USSR5和来自日本的Hatanishiki低温发芽力高，而籼稻品种N22、密阳23低温发芽力弱，这可能与种子对赤霉素（gibberellin, GA）、脱落酸（abscisic acid, ABA）敏感性更强有关，且低温增加了这种敏感性；低温和外源激素处理可能主要通过影响淀粉酶酶带3的活性而起作用；在整个低温萌发过程中，USSR5种子中内源激素ABA含量在相当长的时间内保持较高水平，其GA1/ABA值始终低于N22，这也可能是其低温发芽率高的原因之一。

Physiological Mechanism of Seed Germination ( Oryza sativa L.) Under Low Temperature

High germination rate at low temperature (low temperature germinability, LTG) is an essential characteristic of rice varieties adapted to direct seeding culture. To determine the difference of LTG among the varieties and its physiological mechanism of seed germination under low temperature, Japonica cultivars USSR5, Hatanishiki and Indica cultivars Miyang23 and N22 were used to study the mechanism of seed germination. The results showed that USSR5 came from the former Soviet Union and Hatanishiki came from Japan had higher seed germinability under low temperature, while Miyang23 and N22 with weakly low temperature germinability. The main reasons were that Miyang23 and N22 were more sensitive to GA3, ABA, and low temperature. Furthermore, it was revealed that low temperature and exogenous hormone might affect the seed germination through regulating the activity of amylase type 3 by electrophoresis. During the seed germinating, the USSR5 seed with high LTG contained higher level of endogenous ABA under low temperature than normal, and the ratio of GA1/ABA was lower than that of N22 under low temperature, this may be one of the main reasons of USSR5 with high LTG.