花椰菜种子活力和抗氧化酶活性及幼苗光合色素对NaCl胁迫的响应

以花椰菜银农70天自交系种子为材料，研究了7个NaCl胁迫浓度（0、34、68、102、136、170、204 mmol?L-1）对种子活力和抗氧化酶活性及幼苗光合色素的变化特点。结果发现：① 随着NaCl胁迫浓度的增加，种子发芽率、发芽势、发芽指数、幼苗叶绿素a/b（Chla/Chlb）和类胡萝卜素/叶绿素（Car/Chl）值呈线性降低趋势，丙二醛（MDA）含量呈线性增加趋势。② 种子超氧化物歧化酶（SOD）活性、幼苗干鲜质量以及Chla、Chlb、Chl和Car含量随NaCl胁迫浓度增加呈“钟形”抛物线变化规律，在68～136 mmol?L-1 NaCl胁迫下出现最大值|相对盐害率变化相反，呈“倒钟形”变化特点，在34 mmol?L-1 NaCl胁迫下出现最小值。③ 种子过氧化物酶（POD）和过氧化氢酶（CAT）活性均随NaCl胁迫浓度增加呈多项式变化规律，即在中度NaCl胁迫（136 mmol?L-1）下活性升高，而重度NaCl胁迫（204 mmol?L-1）下降低。综合分析表明，种子相对盐害率、抗氧化酶（SOD、POD和CAT）活性及幼苗Chla、Chlb、Chl和Car含量不仅能较好地指示NaCl胁迫对花椰菜种子活力及相关生理生化的伤害程度，并且可反映其受NaCl胁迫伤害的强度水平，但发芽率、发芽势、发芽指数、Chla/Chlb和Car/Chl值则无法指示|102～136 mmol?L-1 NaCl胁迫浓度是花椰菜种子活力及相关生理生化代谢受到伤害的盐胁迫阈值。

Response of Cauliflower Seed Vigor,Antioxidant Enzyme Activity and Seedling Photosynthetic Pigment to NaCl Stress

The seed vigor,antioxidant enzyme activities and photosynthetic pigment of cauliflower(Brassica oleracea L.var.botrytis L.)’Yinnong 70 tian’were studied under NaCl stresses with concentration as 0,34,68,102,136,170,204 mmol·L-1.It was found that the seed germination percentage,germination energy,germination index,Chla/Chlb and Car/Chl ratio were reduced linearly under NaCl stresses,while malondialdehyde(MDA)content was just the opposite with NaCl stress.The parabola curves in superoxide dismutase(SOD)activity,seedling fresh and dry weight,Chla,Chlb,Chl and Car contents were observed with increasing NaCl stresses and the highest values were obtained under 68-136 mmol·L-1 NaCl stresses;while pattern of the relative ratio of salt disease was the opposite and the lowest value was obtained under 34 mmol·L-1 NaCl stress.The patterns of the peroxidase(POD)and catalase(CAT)activities were displayed different response to salt stresses.Specially,the activities of POD and CAT increased under moderate salty stress,while decreased under severe stress(204 mmol·L-1).It was suggested that the relative ratio of salt stress(136 mmol·L-1),SOD,POD,CAT activities and Chla,Chlb,Chl and Car contents were sensitive indicators that could effectively reflect the response pattern of the physiological and biochemical activities of cauliflower seeds under NaCl stress,but the germination percentage,germination energy,germination index,Chla/Chlb and Car/Chl ratios could not.For cauliflower seeds,the 102-136 mmol·L-1 NaCl was the threshold at which the negative effect of salt stress on seed vigor and some physiological and biochemical characteristics.