15个杜鹃花品种叶片解剖结构与植株耐热性的关系

以15个杜鹃花品种为试材,利用扫描电镜观察叶片17项解剖结构,应用变异系数、相关分析和聚类分析对叶片解剖结构进行筛选,采用隶属函数对各品种的耐热性进行综合评价,探讨杜鹃花叶片解剖结构与植株耐热性的关系,为杜鹃花耐热品种选育、引种栽培及栽培区划分提供细胞学理论依据.结果表明: 杜鹃花叶片为典型的异面叶,表皮细胞垂周壁略呈波浪状,气孔为无规则形,仅分布于下表皮,品种之间有16项解剖结构指标差异达到极显著水平,仅下表皮厚度为显著水平;叶片角质层厚度、气孔密度、气孔宽度、栅栏组织厚度和组织结构疏松度是影响耐热性的主要叶片解剖结构性状,而叶片厚度、气孔长度、孔径、气孔开度、海绵组织厚度、栅海比、上下表皮细胞长度和厚度、组织结构疏松度、中脉厚度与植株耐热性的关系不大.15个品种杜鹃花耐热性存在一定差异,其强弱顺序为:松江大桃红>状元红>绿色光辉>粉珍珠>外国红>蓝茵>笔止>大和之春>国旗红>玉玲珑>红珊瑚>宁波红>套瓣朱砂>爱丁堡>琉球红.15个品种杜鹃花抗热性可划分为4类:松江大桃红、状元红和绿色光辉为抗热类型;粉珍珠、外国红、蓝茵、笔止、大和之春、国旗红和玉玲珑为中度抗热类型;红珊瑚、宁波红、套瓣朱砂和爱丁堡为低抗热类型;琉球红为不抗热类型.杜鹃花耐热性的准确评价需参考形态结构、生理生化、遗传等因素,以及杜鹃花高温受害及受害后恢复状况.

Relationship between leaf anatomical structure and heat resistance of 15 Rhododendron cultivars

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.