五种含笑属植物叶片抗寒结构指标的筛选与抗寒性评价

Screening of leaf cold-resistant structural indexes and cold-resistance evaluation of five Michelia species

为筛选醉香含笑(Michelia macclurei)、‘丹霞’含笑(Michelia‘Danxia’)、紫花含笑(M.crassipes)、‘玉霞’含笑(Michelia‘Yuxia’)和云南含笑(M.yunnanensis)的抗寒结构指标,该文从叶片解剖结构角度评价这五种含笑属植物的抗寒性,分别测定常温、自然降温和低温越冬三个温度节点五种植物的叶片厚度等9项结构指标。通过聚类分析和主成分分析这两种方法筛选抗寒结构指标,并运用隶属函数法来评价五种含笑属植物的抗寒性。结果表明:(1)不同降温阶段聚类分析筛选出的抗寒结构指标不同,常温下,栅海比、海绵组织和下表皮厚度为代表指标;自然降温阶段则是栅海比、海绵组织和角质层厚度为代表指标;而到了低温越冬时期,代表指标变为栅栏组织、海绵组织和上表皮厚度,隶属函数分析显示三个时期五种含笑属植物的抗寒性排序完全不同。(2)主成分分析筛选出的指标为上表皮厚度、栅海比与细胞结构疏松度。隶属函数评价五种含笑属植物的抗寒性排序为醉香含笑>紫花含笑>‘丹霞’含笑>云南含笑>‘玉霞’含笑,与田间观测和生理生化评价结果一致。综上结果表明,以单一时期的叶片结构指标为依据进行聚类分析来筛选抗寒结构指标评价抗寒性的方法存在一定的不足,通过主成分分析筛选指标来进行抗寒性评价的方法更具有参考价值。

In order to screen the cold-resistant structural indexes of five Michelia species(Michelia macclurei,Michelia‘Danxia’,M.crassipes,Michelia‘Yuxia’and M.yunnanensis)and evaluate their cold-resistance according to the leaf anatomy,nine structural indicators such as thickness were measured at three temperature nodes(normal temperature,natural cooling and low-temperature wintering).We selected cold-resistant structural indexes by clustering analysis and principal component analysis,and used the membership function method to evaluate the cold-resistance of five Michelia species.The results were as follows:(1)Cold-resistant structural indexes selected by cluster analysis at different cooling stages were different.At normal temperature,the ratio between palisade tissue and spongy tissue(P/S),sponge tissue(TS)and lower epidermis thickness(TL)were representative indicators;at natural cooling stage,P/S,TS and cuticle thickness(CT)were representative indicators;and in the low-temperature over wintering period,thickness of palisade tissue(TP),TS and thickness of upper epidermis(TU),and the orders of cold-resistance in three periods were completely different according to membership function analysis.(2)The indicators selected by principal component analysis were TU,P/S and looseness of palisade tissue(SR).The cold-resistance of five Michelia species evaluated by membership function was M.macclurei>M.crassipes>Michelia‘Danxia’>M.yunnanensis>Michelia‘Yuxia’.The results were consistent with the field observation and physiological and biochemical evaluation results.It could be concluded that clustering analysis on screening cold-resistant structural indexes and evaluate cold-resistance based on the leaf structure indicators at a single period had certain defects,while the principal component analysis on evaluating cold-resistance by screening indexes had more reference value.