PEG处理对连香树种子萌发与芽苗生长的影响

以连香树种子为试验材料,研究不同质量浓度PEG对种子萌发的影响.结果表明:适宜质量浓度(140～301 g·L-1)的PEG预处理连香树种子,能促进种子萌发和芽苗生长,增加渗透凋节物质如可溶性蛋白、可溶性糖和脯氨酸的含量,提高保护性酶SOD,POD和CAT的活性,降低MDA含量,修复膜系统损伤,提高其抗旱性.在干旱胁迫下,伴随PEG质量浓度的增加,连香树种子萌发和幼苗生长受到抑制,可溶性蛋白含量先升高后降低,可溶性糖、脯氨酸和MDA含量升高,保护性酶SOD和CAT的活性升高及POD活性下降.连香树对干旱胁迫较为敏感,PEG质量浓度≥95 g·L-1对种子萌发、芽苗胚轴和胚根生长产生抑制作用.

Seed Germination and Seedling Growth of Cercidiphyllum japonicum with PEG Treatment

The morphological, physiological and biochemical indexes associated with seed germination and seedling growth of Cercidiphyllum japonicum were measured under treatments of seven different polyethylene glycol ( PEG) mass concentrations from 95 to 345 g·L~(-1). The results showed that the suitable PEG concentration was in a range from 140 to 301 g·L~(-1) . In this range, the membrane-repair capacity and the drought resistance of seeds were improved, accompanied with the changes of the following indicators. The contents of three osmoregulation substances soluble protein, sugar and proline) and the activities of three protective enzymes (superoxide dismutase (SOD) , peroxidase (POD) and catalase (CAT)] were increased, and the content of a final product of lipid peroxidation, malondialdehyde (MDA) was decreased. However, seed germination and seedling growth were inhibited in higher PEG mass concentrations under water stress. With increasing PEG mass concentrations, the contents of soluble sugar, proline and MDA, and the activities of two enzymes (SOD and CAT), were continuously raised, and the enzyme activity of POD was strongly inhibited. In addition, the content of soluble protein was increased first and then decreased in the condition. These results indicated that the seed germination and seedling growth were inhibited under the high PEG mass concentration (≥95 g·L~(-1)) . The results suggest that C. Japonicum seed is sensitive to drought stress.