低温冻害对玉米种子发芽特性及其内部超微结构的影响

以玉米杂交种‘富农1号’的成熟鲜果穗为试验材料,在一定水种子含水量的条件下,通过0、-2、-4、-6、-8、-10℃不同低温和4、6、8h不同时间的处理,研究低温冻害对玉米种子发芽特性及其内部超微结构的影响.结果表明:当玉米种子含水量处于29～31%时,随着温度的降低和时间的延长,种子的发芽势和发芽率都明显下降,且发芽势的下降幅度明显大于发芽率;当温度降到-6℃并持续6h或者当温度降到-8℃并持续4h会使玉米种子的发芽率降到85%以下,不符合国家规定的玉米种子发芽率标准;在-6℃下持续8h后,玉米种子内部的局部淀粉结构发生明显变化,出现微小裂纹,角质淀粉比粉质淀粉更容易被破坏,同时附着于粉质淀粉粒上的部分基质蛋白降解,使淀粉粒表面变得光滑而彼此裸露孤立;低温冻害还会使玉米种皮、糊粉层和胚乳之间以及胚和胚乳之间产生平移断层.

Effects of freezing injury on the germination characteristics and inner ultrastructure of maize hybridize seeds

Mature ears(without husks)of hybridize maize(Zea mays L.)'Funong No.1' was used as material.Germination characteristics and inner ultrastructure of seeds were studied after treated with low temperature of 0℃,-2℃,-4℃,-6℃,-8℃,-10℃and different time of 4h,6h,8h under the given content of moisture.The results showed that when the moisture content of seeds were between 29% and 31%,the germination rate and the germination percentage decreased markedly as the temperature decreased,and the dropping degree of germination rate was higher than germination percentage.In the treatment of -6℃ and 6hor-8℃ and 4h,the germination percentage dropped to 85% which falled short of the acceptance criterion.In the treatment of-6℃ and 8h,the farina ultrastructure had changed evidently,and there was rimula occurred.The damage degree of corneous farina was higher than the farinaceous farina,and the farina matrix protein around the farinaceous farina had partially decompounded.Meanwhile,the displacment fault occurred either between seed coat,aleurone layer and endosperm or embryo and endosperm.