苗期喷施外源脱落酸对北方白菜型冬油菜越冬生理的影响

摘要

To improve cold tolerance of winter rapeseed(Brassica rapa L. )in northern China,hormone effect of exogenous abscisic acid(ABA)was investigated on cultivar Longyou 8. ABA(5,10,15,20,25mg / L)were sprayed on leaves from 6 - 7 true - leaf seedlings. Cold tolerance,physiology and biochemistry characteristics were studied before winter(at 15℃)and during winter(at - 5℃). Results showed that ABA spray significantly im-proved overwintering rate. The overwintering rate was 86. 3% under 20mg / L ABA,which was the highest among other treatments,and was 26. 7% higher than water spray(CK). After spray,leaves protective enzymes(SOD, POD,CAT)were activated significantly. Contents of soluble protein(SP),soluble sugar(SS)and free proline (Pro)were significantly increased. Malonaldehyde(MDA)content was significantly reduced. Root vitality and lat-eral roots were significantly increased. Root collar diameter and root weight increased too,but the increase was not significant different from water control. Result showed that 20mg / L ABA spray was the best concentration to im-prove the cold tolerance of Longyou 8. It was benefited by the increase of protective enzyme activity and osmotic up- regulation from the aerial part. Thus the increase of root vitality and lateral root quantity proved a well condition for the seedling to overcome the chilling.%为提高北方寒旱区冬油菜抗寒性，以白菜型冬油菜陇油8号为材料，在冬前幼苗长至6-7片真叶时，分别用5、10、15、20、25mg/ L 的 ABA 溶液喷施叶片，通过调查越冬率，及日最低温度降至约-5℃时叶片生理指标和根的生长，研究 ABA 对白菜型冬油菜抗寒性的影响。结果表明，喷施 ABA 能显著提高白菜型冬油菜的越冬率，20mg/ L 时越冬率达到最高（86.3%），较 CK 增加26.7%。喷施 ABA 后，受冻时（-5℃）叶片 SOD、POD、CAT 活性显著提高，可溶性蛋白（SP）、可溶性糖（SS）、游离脯氨酸（Pro）含量显著增加，较 CK 增加22.1%～451.8%；丙二醛（MDA）的积累显著降低。喷施 ABA 后，受冻时油菜根系活力极显著增强，侧根数极显著增多，根颈粗、根重均有增加，但不显著。结果显示，20mg/ L 的 ABA 溶液喷施效果最好，表现为酶活性最高，渗透调节物质含量最高，MDA 降幅最大，根系活力最强，侧根数最多。说明在北方寒旱区种植白菜型油菜，6-7片真叶时（冬前）喷施20mg/ L 外源ABA 越冬效果最好，其抗寒性的增强主要是通过增加叶片保护性酶活性和渗透调节物质含量，降低 MDA 含量，从而缓解叶片的低温冻害。同时，通过增加根系活力和侧根数抵御冻害，为及时返青提供保障。