低温胁迫对不同西葫芦品种幼苗生长与生理特性的影响

在昼/夜温度为10℃/5℃的低温胁迫下,对‘特早’、‘早青’、‘冬宝’3个西葫芦(Cucurbit pepoL.)品种的幼苗生长和生理生化指标的变化规律进行研究。结果表明,随着低温处理时间的延长,幼苗单株叶面积、单株干重均有一定程度下降,叶绿素总含量也呈下降趋势;各品种的根系活力显著下降,电导伤害率均明显升高;丙二醛含量在处理9 d时有所下降但整体呈现缓慢上升的趋势,脯氨酸含量呈现逐渐上升的趋势,且处理6 d是脯氨酸和丙二醛两指标测定的理想时期;处理幼苗的POD活性呈"V"字形变化趋势,抗寒性强的品种酶活性也较高,CAT和SOD活性则呈现出先上升后下降的趋势,三者活性均显著高于相应对照,且以处理6 d时酶活性受影响最大。各测定指标间表现出一定的交叉适应和协调性。研究发现,西葫芦耐冷性强弱可根据幼苗电解质渗透率结合根系活力或干物质积累来综合评判,品种‘冬宝’对低温具较强耐受性。

Growth and Physiological Characteristics of Different Pumpkin Cultivars under Low Temperature Stress

The growth and physiological and biochemical indexes of three different pumpkin(Cucurbita pepo L.) cultivars were studied under low temperature and normal temperature.The results indicated that with the time of low temperature treatment increase,the leaf area and dry weight of seedling decreased dramatically.However,the content of chlorophyll presented the slow rise tendency.The root vigor of Tezao,Zaoqing and Dongbao pumpkin variety remarkably dropped after low-temperature treatment,while the electric conductivity rate obviously increased.MDA content increaseed slowly in the whole level but it rose more slowly at 9 days treatment.The proline content showed gradually rise trend.Six days is better treatment time about MDA and the proline content changes.The activity of POD showed as "V" letter and the strong chilling tolerance variety had higher POD activity.The activities of CAT and SOD increased first and then decreased.The activities of the two enzymes was more sensitive with 6 days treatment.The indexes display certain overlapping adaptation and the coordination with each other.The chilling tolerance of seedings could be properly evaluated by comprehensive indexes of electrolyte penetration coefficient combined with root vigor and dry weight accumulation."Dongbao" adapted low temperature stress better among three varieties.