不同化学型油用樟树叶片解剖结构特征及其抗旱特性

Relationship between leaf anatomical structure and drought resistance of different chemotypes oil-used camphor trees

【目的】分析不同化学型油用樟树叶片解剖结构特征及其抗旱性,为樟树品种选育及引种栽培提供理论依据。【方法】以1年生的9种化学型油用樟树(1号~9号)叶片为试验材料,观测其解剖学结构和气孔特征,采用主成分分析结合隶属函数法综合评价各化学型油用樟树的抗旱性。【结果】1号樟树(桉叶油素型)的叶片厚度最厚,为141.16μm,显著高于其他化学型油用樟树(P<0.05,下同);6号樟树(龙脑型)的叶片厚度最薄,显著低于其他化学型油用樟树。1号和2号樟树(芳樟醇型I)叶片的栅栏组织厚度较厚,分别为65.55和65.67μm,二者差异不显著(P>0.05,下同),但显著高于其他化学型油用樟树;6号樟树叶片的栅栏组织厚度最薄,为45.37μm,4号樟树(黄樟油素型)次之,二者差异不显著,但显著低于其他化学型油用樟树。4号和9号樟树(柠檬醛型II)的叶脉密度较大,分别为8.86和8.14 mm/mm^2,二者差异显著,且显著大于其他化学型油用樟树;7号樟树(柠檬醛型I)的叶脉密度最小(2.14 mm/mm^2),显著小于其他化学型油用樟树。气孔密度较大的是1号和3号樟树(芳樟醇型II),分别为430.0和436.0个/mm^2,二者差异不显著,但显著大于其他化学型油用樟树;气孔密度最小的是7号樟树,为227.0个/mm^2,显著小于其他化学型油用樟树。在保卫细胞长度方面,7号和8号樟树较大,2号和3号樟树较小。综合评价结果表明,桉叶油素型的1号樟树、芳樟醇型I的2号樟树和芳樟醇型II的3号樟树抗旱性较强,黄樟油素型的4号樟树抗旱能力最弱。【结论】叶片厚度、中脉导管直径、栅栏组织厚度和气孔密度可作为评价樟树抗旱能力的叶解剖结构特征指标;桉叶油素型、芳樟醇型I和芳樟醇型II樟树抗旱性较强,可在我国长江以南地区引种栽培,黄樟油素型的抗旱能力最弱,不宜引种。

【Objective】In order to provide a theoretical basis for variety breeding,introduction and cultivation of camphor tree,the relationship between camphor tree leaf anatomical structure and drought resistance of different chemotypes oil-used camphor trees was explored in this paper.【Method】Taking one-year-old leaves of nine chemotypes oil-used camphor trees(numbers were 1-9)as materials,anatomical structure and stomata characteristics were determined.Combined with principal component analysis,the drought resistance of the trees were evaluated by membership function method.【Result】The results showed that,the leaf thickness of camphor tree No.1(cineole-type)was the maximum,up to 141.16μm,which was significantly larger than other chemotypes oil-used camphor trees(P<0.05,the same below).The leaf thickness of camphor tree No.6(borneol-type)was the minimum,which was significantly smaller than other chemotypes oil-used camphor trees.Palisade tissue thickness of camphor tree No.1 and No.2(linalool I-type)were large(65.55 and 65.67μm),there were no significant difference between the two(P>0.05,the same below),but they were significantly larger than other trees.The minimum palisade tissue thickness belonged to No.6(borneol-type)(45.37μm),followed by camphor tree No.4(safrole-type).There were no significant difference between the two,but they were significantly smaller than other trees.Camphor tree No.4(safrole-type)and No.9(citral II-type)had thick vein density(8.86 and mm/mm^2),the difference between the two was significant,and they were significantly larger than other trees.However the minimum vein density(2.14 mm/mm^2)belonged to No.7(citral I-type),which was significantly smaller than other chemotypes oil-used camphor trees.The large values of stomatal density were camphor tree No.3 and No.1(linalool IItype),up to 436.0 and 430.0 stoma/mm^2.The difference between the two was not significant,and they were significantly larger than other trees.The minimum stomatal density was camphor tree No.7(227.0 stoma/mm^2),it was significantly smaller than other trees.camphor tree No.7 and No.3 had short guard cell length.The results of comprehensive evaluation showed that,camphor tree No.1(cineole-type),camphor tree No.2(linalool I-type)and camphor tree No.3(linalool IItype)had stronger drought resistance,and camphor tree No.4(safrole-type)had the weakest drought resistance.【Conclusion】According to statistical analysis,the main anatomical structure indexes affecting drought resistance are leaf thickness,diameter of vessel in midrib,palisade tissue thickness and stomatal density.The three varieties with the strong drought resistance arecineole-type,linalool I-type and linalool II-type camphor trees,they can be introduced to the southern region of Yangtze River.Safrole-typecamphor tree has the weakest drought resistance and should not be introduced.