Effects on Cold Tolerance of Winter Rapa(Longyou 8)Under Exogenous ABA

In order to study effects on cold tolerance of winter rapa under exogenous ABA,the experiment was carried out in the field before the wintering,Longyou 8 as the material,spraying ABA by different concentrations(0,5,10,15,20,25 mg· L- 1),and in different periods(3 leaf stage,5 leaf stage,6 leaf stage,7 leaf stage),the changes of MDA,soluble sugar( SS) content,soluble protein( SP) content,wintering rate and yield of rapa were determined and analyzed. The results showed,after spraying ABA on leaves,the MDA content of winter rapa decreased,while the content of soluble sugar,the content of soluble protein,winter survival rate and yield increased. According to the results,it was suggested that the best time to spray ABA on winter rapa was between five leaf stage and six leaf stage,and the best concentration should be 15 to 20 mg·L- 1,because it could effectively improve the cold tolerance of winter rapa. The research provides a technological support to the safety wintering of winter rapa.