Inducing effects of plant growth regulators on the chilling resistance of sweet pepper (Capsicum annuum)

The inducing effects of plant growth regulator MIX Ⅱ,which is the mixture of coronatine (COR),abscisic acid (ABA) and mineral fulvic acid (MFA),was analyzed on increasing the chilling resistance of five sweet pepper varities.After transplanting for 7 d,seedling roots were watered by 10 mL MIXⅡ per plant,then seedlings were grew under 10-15 ℃ for 60 d,and then were exposed to low temperature (5 ℃) for 48 h.The seedling growth, cytoplasmic membrane permeability,osmoregulation substance,the hydrogen peroxide and antioxidant enzyme activity were measured in different sweet pepper varieties, and the differences of these characteristics were analyzed between the treatments and control.The results showed that the protection effects of MIXⅡon the seedlings growth of different sweet pepper varieties were different.The antioxidant enzymes activities were increased,the injury of oxygen to cytoplasmic membrane and the relative electrolyte leakage were reduced;The content of osmoregulation substance of proline and K+ in seedling leaves were increased,and the cell osmotic potential and the cell metabolism were maintained at normal level.As a result,the chilling resistance of different sweet pepper varieties were improved by MIXⅡunder chilling stress.