桉树抗桉树枝瘿姬小蜂理化因子的多元回归分析

Multiple Regression Analysis of Physicochemical Factors on Resistance of Eucalyptus against Leptocybe invasa

关键词:  桉树  抗虫性  桉树枝瘿姬小蜂  多元回归分析

Key words:  Eucalyptus  insect resistance  Leptocybe invasa  multiple regression analysis

摘要:

[目的]通过对桉树抗桉树枝瘿姬小蜂(Leptocybe invasa)相关的多个理化指标进行多元回归分析,确定与抗虫性最紧密关联的关键因子,为筛选抗虫桉树品系提供理论指导。[方法]首先比较了窿缘桉Eucalyptus exserta(EA)、巨圆桉Eucalyptus grandis×Eucalyptus tereticornis(DH201-2)和巨尾桉Eucalyptus grandis×Eucalyptus urophylla(G9)3个桉树品系对桉树枝瘿姬小蜂的抗性强弱,同时测定了桉树品系间叶片含水率、叶片厚度、比叶面积(Specific leaf area,SLA)、叶片C含量、N含量、C/N比、总酚、缩合单宁等8个理化指标,最后通过多元逐步回归分析筛选出与抗虫性紧密关联的理化因子,并建立回归方程。[结果]桉树枝瘿姬小蜂不能在G9上产生虫瘿,在DH201-2上的样枝平均虫瘿数显著高于EA。3个桉树品系叶片厚度间无显著差异;DH201-2叶片含水率显著高于EA和G9;N含量表现为DH201-2 > EA > G9;G9叶片C含量、总酚和缩合单宁含量显著高于EA和DH201-2。通过多元逐步回归分析,最终进入模型的是缩合单宁(X₂)和C含量(X₃);建立了以抗性得分为因变量(Y),缩合单宁含量(X₂)、C含量(X₃)为自变量的回归方程:Y=-20.671+2.095X₂+0.433X₃(复相关系数R=0.770,校正相关指数R²=0.578,显著水平P<0.001)。[结论]缩合单宁和C含量是影响桉树对桉树枝瘿姬小蜂抗性强弱的关键因子,且两个因子与抗虫性正相关;所建立的回归方程可以很好地预测桉树抗虫性与两个化学指标间的相关关系,为今后选育桉树抗虫优良品系提供理论依据。

Abstract:

[Objective] Using multiple regression analysis to drive the relation between multiple physicochemical indexes and resistance of eucalypts against Leptocybe invasa, this study aims to identify primary factors that closely relate to herbivore resistance of eucalypt species, and to provide valuable scientific guidance for screening herbivore resistant hybrids through crossbreeding in future.[Methods] Three Eucalyptus species[E.exserta, DH201-2 (E.grandis×E.tereticornis) and G9 (E.grandis×E.urophylla)]were selected, and the resistance of three species against L.invasa was compared. Eight leaf physicochemical indexes including thickness, water content, specific leaf area, C, N, C/N ratio, total phenolics and condensed tannins were comprehensively measured. Multiple stepwise regression analysis were performed to screen main factors related to herbivore resistance, and a regression equation was established.[Results] L.invasa could not induce galls on G9, while gall number on DH201-2 was significantly higher than that on EA.Leaf thickness of the three species were similar to each other. The water content in the leaves of DH201-2 was significantly higher than that in the leaves of G9 and EA. Similarly, N content in the three species was DH201-2 > EA > G9. C content, total phenolics, and condensed tannins in G9 were significantly higher than those in EA and DH201-2.Condensed tannins and C finally entered into the model through stepwise multiple regression analysis. Using the herbivore resistance score (Y) as dependent variable and condensed tannins (X₂) and C content (X₃) as the independent variables, the regression equation was established as Y=-20.671+2.095X₂+0.433X₃ (multiple R=0.770, adjusted R²=0.578, P<0.001).[Conclusion] Our results showed that condensed tannins and C content were key factors which positively influenced the resistance of Eucalyptus against L.invasa.The change of above chemical indexes would provide scientific guidance for the determination of the breeding index of high resistant Eucalyptus varieties in future.