Shen Hui Fei, Zhao Bing, Xu Jing Jing
College of Landscape Architecture and Arts, Northwest A&F University, Yangling 712100, Shaanxi, China.
Ying Yong Sheng Tai Xue Bao. 2016 Dec;27(12):3895-3904. doi: 10.13287/j.1001-9332.201612.013.
In this study, 17 anatomical structure indexes of 15 Rhododendron cultivars were mea-sured by scanning electron microscope (SEM). Leaf anatomical structure indexes were screened via coefficient of variation, analysis of correlation and hierarchical cluster analysis, and comprehensive evaluation on heat resistance for each cultivar was conducted by the subordinate function. The results showed that the leaves of Rhododendron cultivars were typical bifacial leaf and the epidermal anticlinal walls showed slightly sinuate. The stomata only distributed in the lower epidermis and the shape was ruleless. The anatomical structure indexes all reached a significant level difference among 15 cultivars (P<0.01), except for lower epidermis thickness (P<0.05). Thickness of lamina corneum, stomatal density, stomatal width, the thickness palisade tissue and looseness of leaf spongy tissue were the main factors related to the hardness, while other indexes, such as stomatal length, stoma aperture, stomatal opening, length and thickness of upper epidermis, length and thickness of lower epidermis, thickness of spongy tissue, the ratio of the palisade tissue to spongy tissue, tightness of leaf palisade tissue, leaf thickness and media thickness didn't show much effect on heat resistance. There were some differences among 15 cultivars in heat resistance, and the order was Rhododendron 'Song Jiang Da Tao Hong' > Rhododendron 'Zhuang Yuan Hong' > Rhododendron 'Lv Se Guang Hui' > Rhododendron 'Fen Zhen Zhu' > Rhododendron 'Wai Guo Hong' > Rhododendron 'Lan Yin' > Rhododendron 'Bi Zhi' >Rhododendron 'Da He Zhi Chun' > Rhododendron 'Guo Qi Hong' > Rhododendron 'Yu Ling Long' > Rhododendron 'Hong Shan Hu' > Rhododendron 'Ning Bo Hong' > Rhododendron 'Tao Ban Zhu Sha' > Rhododendron 'Ai Ding Bao' > Rhododendron 'Liu Qiu Hong'. According to the heat hardiness, the cultivars could be divided into 4 groups: R. 'Song Jiang Da Tao Hong', R. 'Zhuang Yuan Hong' and R. 'Lv Se Guang Hui' with high heat resistance, R. 'Fen Zhen Zhu', R. 'Wai Guo Hong', R. 'Lan Yin', R. 'Bi Zhi', R. 'Da He Zhi Chun', R. 'Guo Qi Hong' and R. 'Yu Ling Long' with medium heat resistance, R. 'Hong Shan Hu', R. 'Ning Bo Hong', R. 'Tao Ban Zhu Sha' and R. 'Ai Ding Bao' with lower heat resistance, R. 'Liu Qiu Hong' without heat resistance. However, the accurate heat hardiness evaluation of Rhododendron still needs to consider other factors, including morphological structure, physiological and biochemical indicators and genetic factor of heat resistance, the harmfulness of Rhododendron, and the recovery state after being injured by high temperature.
本研究采用扫描电子显微镜（SEM）对15个杜鹃花品种的17个解剖结构指标进行了测定。通过变异系数、相关性分析和层次聚类分析筛选叶片解剖结构指标，并利用隶属函数对各品种的耐热性进行综合评价。结果表明，杜鹃花品种叶片为典型的异面叶，表皮细胞垂周壁呈浅波状。气孔仅分布在下表皮，形状不规则。除下表皮厚度差异达显著水平（P<0.05）外，15个品种间各解剖结构指标差异均达极显著水平（P<0.01）。角质层厚度、气孔密度、气孔宽度、栅栏组织厚度和叶片海绵组织疏松度是影响硬度的主要因素，而气孔长度、气孔孔径、气孔开度、上表皮长度和厚度、下表皮长度和厚度、海绵组织厚度、栅栏组织与海绵组织比值、叶片栅栏组织紧密度、叶片厚度和中脉厚度等指标对耐热性影响不大。15个品种的耐热性存在一定差异，其耐热性顺序为：杜鹃花‘松江大桃红’>杜鹃花‘状元红’>杜鹃花‘绿色光辉’>杜鹃花‘粉珍珠’>杜鹃花‘外国红’>杜鹃花‘兰茵’>杜鹃花‘碧芝’>杜鹃花‘大和之春’>杜鹃花‘国旗红’>杜鹃花‘玉玲珑’>杜鹃花‘红珊瑚’>杜鹃花‘宁波红’>杜鹃花‘陶瓣朱砂’>杜鹃花‘爱丁堡’>杜鹃花‘琉球红’。根据耐热性，可将这些品种分为4组：耐热性高的‘松江大桃红’‘状元红’和‘绿色光辉’；耐热性中等的‘粉珍珠’‘外国红’‘兰茵’‘碧芝’‘大和之春’‘国旗红’和‘玉玲珑’；耐热性较低的‘红珊瑚’‘宁波红’‘陶瓣朱砂’和‘爱丁堡’；无耐热性的‘琉球红’。然而，杜鹃花准确的耐热性评价仍需考虑其他因素，包括形态结构、生理生化指标和耐热性遗传因子、杜鹃花的危害性以及高温伤害后的恢复状态等。
