王馨 易拓 朱杰辉 宋勇

摘  要：為探究低温胁迫对木薯显微结构和光合效率的影响，对木薯耐寒品种‘F200和常栽低温敏感型品种‘华南8号（‘SC8）在人工低温条件下进行4 ℃低温处理，观察处理前和处理3、6、12、24 h下幼苗叶片的扫描电镜、透射电镜及叶绿素荧光参数变化情况，并比较两品种间的差异。结果表明：（1）与‘SC8相比，随着气温的降低‘F200的叶片气孔会逐渐关闭且叶片蜡质形成自我保护机制;（2）低温胁迫状态24 h后，‘F200叶肉细胞内细胞器仍维持工作状态，而‘SC8叶肉细胞基本死亡;（3）2个品种最大叶绿素荧光强度下降且达到最大荧光所需时间均增加，‘F200的最大荧光值高于‘SC8;（4）低温胁迫下，‘F200的各项叶绿素荧光参数应急反应强度低于‘SC8，说明‘F200对于在低温逆境环境中生长的能力强于‘SC8。

关键词：木薯;低温;显微;叶绿素荧光

中图分类号：S533      文献标识码：A

Effect of Low Temperature Stress on Leaf Submicroscopic Structure and Chlorophyll Fluorescence Parameters of Cassava ‘F200 Seedlings

WANG Xin1， YI Tuo1， ZHU Jiehui1，5*， SONG Yong1，2，3，4*

1. College of Horticulture， Hunan Agricultural University， Changsha， Hunan 410128， China; 2. Potato Center of Hunan Province， Changsha， Hunan 410128， China; 3. Engineering Research Center for Horticultural Crop Germplasm Creation and New Variety Breeding， Ministry of Education， Changsha， Hunan 410128， China; 4. Key Labortory for Vegetable Biology of Hunan Province， Changsha， Hunan 410128， China; 5. Orient Science &Technology College of Hunan Agricultural University， Changsha， Hunan 410128， China

Abstract： In order to investigate the effects of low temperature stress on the microstructure and photosynthetic efficiency of cassava， cold resistant cassava variety ‘F200 and low-temperature sensitive cassava variety ‘Huanan 8 （‘SC8） were treated at 4 ℃ under artificial low temperature condition. Scanning electron microscopy （SEM）， transmission electron microscopy （TEM） and chlorophyll fluorescence parameters were observed before and after 3 h， 6 h， 12 h and 24 h treatment， and the differences between the two varieties were compared. The results showed that： Compared with ‘SC8， with the decrease of air temperature， the stomata of ‘F200 leaves gradually closed and the wax in leaves formed a self-protection mechanism. After 24 h of low temperature stress， the organelles in ‘F200 mesophyll cells maintained functioning， while the mesophyll cells of ‘SC8 basically died. The maximum chlorophyll fluorescence intensity of the two cultivars decreased and the time required to reach the maximum fluorescence increased. The maximum fluorescence value of ‘F200 was higher than that of ‘SC8. Under low temperature stress， the emergency response intensity of various chlorophyll fluorescence parameters of ‘F200 was lower than that of ‘SC8， indicating that ‘F200 had a stronger ability to grow in low temperature adversity environment than ‘SC8.

Keywords： cassava; low temperature; microscopy; chlorophyll

DOI： 10.3969/j.issn.1000-2561.2021.07.015

木薯（Manihot esculenta Crantz）大戟科植物[1]，适宜生长在平均温度约为18 ℃以上且全年无霜期最低8个月的地区，当气温低于15 ℃时生长发育逐渐受到抑制，温度低于4 ℃便停止生长[2-3]。中国完全适合木薯生长的地区较少，为扩大木薯的种植面积，保证我国的粮食安全，国家陆续多次出台相关政策，例如：“木薯北移”战略，将湖南等多省份作为适宜木薯种植的北移区域[4]。

不同环境下叶片相应的形态和结构会发生不同的变化[5]。低温的状态下叶片中的细胞器和膜结构反应尤为明显[6]。气孔作为植物与外界进行气体交换和水汽蒸腾的通道与叶片正常的功能运转有着密切的联系[7]。叶绿素对低温较敏感，其含量直接影响光合作用效率和光合产物的合成[8]。……