低温胁迫对烟苗叶形及生理特性的影响

为了解低温胁迫后烟苗的生理机制及恢复生长后叶形变化规律，以烤烟K326的7叶龄烟苗为试验材料，测定了其在4℃低温胁迫3、6、12、24和48 h后的相关生理指标，并将4℃低温胁迫后的烟苗于25℃（对照）下恢复生长，测量其叶长、叶宽变化。结果表明，随低温胁迫时间增加，相对电导率、脯氨酸含量和可溶性糖含量不断升高；丙二醛（MDA）和叶绿素含量先升高后降低；过氧化氢酶（CAT）活性不断降低；超氧化物歧化酶（SOD）活性和过氧化物酶（POD）活性变化不大。低温胁迫显著抑制叶片长、宽和叶面积，对叶宽的抑制作用强于叶长，从而增大叶片长宽比。低温胁迫后恢复生长16 d，叶片长宽比趋于稳定。不同低温胁迫时间诱导程度为12 h >24 h >6 h >3 h >48 h。

Effects of Low Temperature Stress on Leaf Shape and Physiological Characteristics in Tobacco Seedlings

In order to study the physiological responses of tobacco seedlings to low temperature stress and the change of leaf shape after resuming growth, 7th-leaf stage tobacco seedlings of ‘K326’ were used to measure the physiological indicators of tobacco seedlings at 4℃ and 25℃ for 3, 6, 12, 24 and 48 h. After 4℃ low temperature stress the tobacco seedlings were returned to 25℃ to resume growth. The changes of leaf length and leaf width were measured. The results showed that the relative conductivity, proline content and soluble sugar content increased with the increase of low temperature stress time; the contents of malondialdehyde (MDA) and chlorophyll increased first and then decreased; the activity of catalase (CAT) decreased continuously; the activity of superoxide dismutase (SOD) and peroxidase (POD) had no significant change. After low temperature stress, the leaf length, leaf width and leaf area were significantly inhibited, and the inhibition of leaf width was stronger than that of leaf length, thus increasing the length-width ratio of leaves. After low temperature stress, the length-width ratio of leaves tended to be stable after resuming growth for 16 days. The induction of stress responses of different low temperature stress time was 12 h > 24 h > 6 h > 3 h > 48 h.