(40(3):255-261)Dynamic Studies on Concurrence with Growth Time in Linear Regression Analysis of Genotype-Environment Interactions

直線迴歸模式能有效地估計數量性狀對環境的適應能力。然而，利用交感效應隨環境指標所求得的〝穩定性〞，係一種相對性的概念，隨參試材料與環境因子的種類、數目之不同，其估值也改變，因此，直線迴歸模式實為一種描述性的穩定性模式，而無法用之於預測工作，同時也造成表型平均值與穩定性係數之間往往存在正相關關係。此種相關的情況，即所有迴歸線通過一共點。在符合直線迴歸模式且基因型與環境效應均為逢機型之前提下，由逢機樣本估得之共點乃提供了一預測上極有用的指標。另一方面，植物性狀的穩定性常因生長及發育的不同而異，故所估得之共點介量也會隨生長時間而有變化。因此針對此問題，本研究將以實驗植物Arabidopsis thaliana為材料，建立共點介量與生長時間的特定關係，以探明共點性隨著生長發育之變化趨勢，俾能誘導出一測定穩定性的預測模式。 結果得知：各生長時間下除了第1週外，共點性均存在，所估計的共點皆落在生產正常範圍內，故採用迴歸係數估值作為穩定性之選拔準則有效，然其所選出的高產且穩定基因型會因生長時間之不同而改變。由本研究Arabidopsis thaliana的資料配合結果，顯示共點係數ct與時間t之間呈一種指數生長曲線關係，其值在生長初期最大而隨時間經過則變小，此可用以預測同族群其他未受試之基因型及環境，但預測的可靠性僅侷限於該特定時間內。Linear regression model is useful to evaluate the adaptation of a quantitative character to the change of environments. However, the stability in the regression model is a relative measure depending on the genotypes and environments included in the test. Therefore, the regression model for G×E interaction is a descriptive model based on the data being analysed, but not a predictive model. This results in positive correlations between the phenotypic mean and regression coefficient. The correlations to occur is that all regression lines for all genotypes pass throught a common point, that is the regression should be concurrent. The concurrent point can be used to predict the performance of untried genotype when grown in a hypothetical environment, if both genotype and environment are considered as random samples from larger populations. Moreover, the stability of a quantitative character of a plant often varies with time at different stage of growth and development. This results in the diversity of concurrence for different periods. Thus, this project is to study the tendency of concurrence with growth time, and establish a forecasting model in plant stability by inducing the close relationship between concurrence and growth time into the linear model. The experiments will be conduced to test reliability and applicability of the above-mentioned empirical model by using Arabidopsis thaliana plants as materials. The results show that the concurrence occurred at various plant growth stages except the first week. With a close relationship between concurrent parameter and growth time, a combined concureent model was then introduced. It appeared to be an exponential curve based on the data of Arabidopsis thaliana, thus it can be used to predict the performance of an untried genotype when grown in a hypothetical environment at different growth time, if both genotype and environment are considered as random samples from larger populations