菊花近缘种属植物幼苗耐阴特性分析及其评价指标的确定

以龙脑菊、菊花脑、野菊等15个菊花近缘种属植物幼苗为材料,对其进行不同梯度遮荫处理(全光照,遮光率60%,遮光率78%,遮光率95%),从形态和生理等方面的22个指标进行测定,以各项指标的耐阴系数作为衡量耐阴性的指标,利用主成分分析、回归分析和聚类分析法对其耐阴性进行综合评价。结果表明:遮光率78%时的植物茎粗(X2)、叶片厚度(X10)、叶绿素含量(X16),遮光率60%时的植物叶绿素含量(X15),以及遮光率95%时的植物叶面积(X13)、相对含水量(X14)和胞间二氧化碳浓度(X21)8个指标可作为菊花近缘种属植物耐阴性评价指标,建立菊花近缘种属植物耐阴性评价的数学模型:Y=82.876-0.153X2+0.094X10+0.741X13+0.084X14+0.054X15-0.087X16-0.472X2,(R2=0.998),预测精度大于0.97。13份材料的耐阴性极强,矶菊的耐阴性较差,即多数菊花近缘种属植物具有较好的耐阴能力。

Analysis of shade-tolerance and determination of evaluation indicators of shade- tolerance in seedlings of Chrysanthemum grandiflorum and its closely related genera

Chrysanthemum (Chrysanthemum grandiflorum (Ramat.) Tzvel.) is one of the most important ornamentals, enjoying a major share of the cut flower and flowering pot plant market worldwide. The related taxa of Chrysanthemum have been shown to be tolerant to various biotic or abiotic stresses such as pest, fungi, drought or salt stress etc, so the useful gene can be used to the elite germplasm and new variety breeding of Chrysanthemum by interspecific hybridization or gene engineering. Several representative species of Chrysanthemum and its related genera, maintained at the Chrysanthemum Germplasm Resource Preserving Center, " Nanjing Agricultural University ", were used in this study. Seedlings of fifteen species from Dendrathema and Ajania generus such as D. makinoi, D.nankingense, D.indicum, D.yoshinaganthum, D. japonense, D.crassum, D.makinoi var. akasaense, D. okiense, D.vestitum, Ajania przewalskii, A. pacificum, A.shiwogiku, Artemisia vulgaris, A.abrotarum, A. japonicawere subjected to shading treatment. Morphological and physiological parameters including stem diameter, internode length, leaf width, leaf length, leaf thickness, leaf area, relative water content, chlorophyll content, net photosynthetic rate (Pn), intercellular CO₂ concentration (Ci), stomatal conductance (Gs) and transpiration rate (Tr) of seedlings were determined under non-shading, 60%, 78% and 95% shading rate, respectively. Our results showed that thirteen out of fifteen species including D. makinoi, D.nankingense, D.indicum, D.yoshinaganthum, D. japonense, D.crassum, D.makinoi var. akasaense, D. okiense, D.vestitum, Ajania przewalskii, A.shiwogiku, Artemisia vulgaris, A.abrotarum are shade-tolerant with longer leaf length, thiner leaf thick, higer chlorophyll content, no change of relative water content and intercellular CO₂ concentration than that of control, while Ajania pacificum is sensitive to shade tolerance with abnormal phenotype such as the smallest leaf length and leaf area, the lowest chlorophyll content, the highest relative water content and intercellular CO₂ concentration than its control, the sensitivity of the other one A. japonica to shade treatment was lower than that of Ajania pacificum but higher than that of the thirteen species. It suggests that most of the species from Chrysanthemum and Ajania are shade tolerant plants. The co-efficiency of different indexes was used to evaluate the shade tolerance of the plants. The shade tolerance of the tested 15 species was evaluated using the principle component analysis, regression analysis and hierarchical cluster analysis. The results showed that stem diameter (X₂), leaf thickness (X₁₀) and chlorophyll content (X₁₆) under 78% shading, chlorophyll content (X₁₅) under 60% shading, and leaf area (X₁₃) and relative water content (X₁₄) and intercellular CO₂ concentration (X₂₁) under 95% shading were suitable indexes for shading tolerance evaluation. The mathematical evaluation model for chrysanthemum shade-tolerance was Y=82.876-0.153X₂+0.094X₁₀+0.741X₁₃+0.084X₁₄+0.054X₁₅-0.087X₁₆-0.472X₂(R²=0.998), established based on above mentioned indexes, and the predicting accuracy of the model is as high as 0.97. It indicates that comprehensive assessment the shade-tolerance with the co-efficiency of different indexes is more effective and accurate, avoiding the segmentary evaluation of just one index or the reduplicate evaluation of more indexes. Together, our data suggest that the mathematical evaluation model based on the indexes using the principle component analysis, regression analysis and hierarchical cluster analysis is reliable and useful to assess the shade tolerance of Chrysanthemum grandiflorum and its closely related taxa.