【作者】 南铭；

【导师】 王汉宁；

【作者基本信息】 甘肃农业大学 ， 作物遗传育种， 2010， 硕士

【摘要】 玉米种子是农业生产中最基本的生产资料,玉米种子的安全生产直接影响其质量的高低,进而影响农业生产和粮食安全,关系到农民的切身利益和实际利益。而低温冻害又是影响我国北方主要制种基地玉米种子安全生产的关键环境因子,玉米种子在收获并贮藏过程中极易遭受低温冻害,在我省河西走廊玉米制种基地时有发生,造成了一定的经济损失。本文以新鲜收获的不同粒型玉米杂交种子富农1号(硬粒型)、郑单958(中间型)、辽单565(马齿型)为研究对象,测定了不同粒型玉米种子的发芽率、发芽势、种子发芽指数、电导率、可溶性糖含量及其超氧化物歧化酶、过氧化物酶、淀粉酶活性。系统分析了几项指标与不同粒型玉米种子抗冻性的变化关系。研究结果表明：1.不同粒型玉米种子的发芽率均随温度降低而降低,硬粒型种子相对其它两种粒型在低温冻害下有较高的萌发速率；不同粒型玉米种子的受冻程度与其含水量、冻害温度及时间有关,对发芽率、发芽势和发芽指数均具有显著影响；三种粒型发芽率在-10℃左右变化明显;当籽粒含水量在15%-20%以上时,-10℃以下低温处理使种子发芽率降低；当种子含水量在15%-20%以下时,-10℃以下低温处理不会影响种子发芽率和发芽势,当温度低于-25℃时,三种粒型种子发芽率、发芽势和发芽指数都显著下降。2.低温冻害导致膜孔隙变大,细胞内离子大量外泄,电导率增大。电导率与低温及低温持续期有关,温度越低,低温处理时间越长,细胞膜系统破坏越严重,电导率越大；当籽粒含水量在15-20%以上时,-10℃低温处理前后电导率变化显著;富农1号质膜伤害程度最小,硬粒型种子对低温具有一定的抵御能力,抗冻能力强；辽单565受低温影响严重,马齿型种子抵御低温的能力较差。3.低温冻害造成不同粒型玉米种子内部保护酶系统平衡失调,使玉米种子SOD和POD活性升高。耐低温冻害粒型酶活性比不耐低温粒型酶活性变化显著；酶活性与低温及低温持续期有关,单一因素和多因素互作对酶活性影响极显著;硬粒型种子POD活性和SOD活性均较其它两种粒型强,抗低温冻害能力较强。4.通过低温处理,三种粒型玉米种子可溶性糖含量有不同幅度提高,变化趋势基本一致。不同粒型种子可溶性糖含量受冻害温度及时间和含水量影响；可溶性糖含量越高,玉米种子抗低温冻害能力越强。三种粒型玉米种子抗冻性强弱为富农1号(硬粒型)>郑单958(中间型)>辽单565(马齿形)。5.低温冻害下,种子淀粉酶活性增强,淀粉积累下降。低温及低温持续期对淀粉酶活性影响显著。更多还原

【Abstract】 Seed of maize is the most basic means of production of agriculture, its security of producing affects its quality, thus affects agricultural production and food security, relating to the vital interests of farmers and practical benefits. Low-temperature damage in northern China is a vital environmental factor to impact security of seed production, from which seed is very easy to get hurt during harvest and storage, which happens very often in seed production bases of Hexi Corridor, Gansu province, and causes a certain amount of economic losses. The freshly harvested maize kernels of different grain type of Funongl, Zhengdan958, Liaodan565 were used in this research to measure their germination rate, germinability, seed vitality index, electrical conductivity, soluble sugar content and superoxide dismutase, peroxidase, amylase activity. The relationships of the indicators with variation of freezing resistance of different shapes of maize kernels were analyzed systematically. The results showed as following.1. The germination rate of maize kernels of different shapes decreased as the temperature decreasing, the germination rate of durum maize was higher at freezing injury than other shape of maize. The germination rate decreased with time longer at low-temperature. The freezing injury of maize of different types was positively related to water content, freezing injury temperature and time, which significantly affected germination rate, germination energy and germination index. The seed vigor of maize of these three different types changed significantly at-10℃. The germination rate of maize kernels decreased because of low-temperature damage when the temperature was under-10℃and water content above 15%-20%, and it the low temperature did not affected the germination rate of maize kernels when the temperature was above-10℃and water content below 15%-20% with germination rate and germination energy unaffected, SV and quality of seed unchanged. When the temperature was below-25℃, the germination rate, germination energy and germination index dropped to minimum.2. Freezing injury caused to membrane pore larger, a lot of leakage of intracellular ions, the conductivity increasing. The electrical conductivity was positively correlated to temperature and freezing time, significantly affected conductivity. With temperature lower and the freezing time longer, the conductivity was larger and the cell membrane system was damaged more seriously. The cell membrane of Funongl was damaged at lightest level, which indicated that durum type has a certain resistance to low temperature, relative stability of cell membrane structure, the best antifreezing capability. The anti-freezing capability of Liaodan565 was not very nice.3. Freezing injury caused imbalance and severe damage of the protective enzyme system of seed of different grain type. SOD and POD activity in maize seeds gradually increased, and the variation was not exactly the same. The changes of enzyme activity of low temperature resistant grain type were much more significant than that of low temperature non-resistant grain type. Enzyme activity was positively corelated to the temperature and freezing time. Single and multiple interactions affected enzyme activity significantly, which was possibly caused by the differences of resistance of maize of different grain type. POD activity and SOD activity of Durum-type seeds increased more significantly than those of the other two grain types, indicating that it has a strong resistance to low temperature.4. Treated with low temperature, the sugar content of maize seed of three grain types increased at different degrees and the trend of changes was similar. The accumulation of soluble sugar increased the cell osmotic pressure and water retention, so that materials within cells was hard to be frozen at low temperatures, intracellular metabolic activity kept normal, role resistant to low temperature was played. Seed soluble sugar content of maize of different grain type was positively related to temperature, freezing time and water, and correlation was significant. The higher soluble sugar content of maize seeds, the stronger resistance to low temperature and freezing capacity. Frost resistance strength was FunongNol>Zhengdan958>Liaodan565.5. Under low-temperature damage, the amylase activity of maize seeds was increased, and the starch accumulation was decreased. The factors of low-temperature and low-temperature duration had a significantly effect on amylase activity.更多还原