(45(3):218-229)Estimation of Missing Plot for Stability Analysis in Crop Regional Trials

育種程序中作物區域試驗施行之目的，在選出高產且穩定之品種。本省區域試驗一般採用的穩定性介量多以最受廣泛使用的直線迴歸分析法為主。該法僅適用於每一基因型與環境組合都有資料之場合，因此一旦含有缺區，便無法正確估得環境指標，並進行穩定性分析；過去一般處理缺區的方式，係將含缺區的品系或環境全部刪除，使其呈均衡資料後，再進行穩定性分析，如此在缺區數多時勢必會造成品系或環境數減少，反而降低了評估結果的準確度。因此本研究擬在不摒除任何品系及環境數之情況下，利用傳統的缺區估計法使填入缺區估計值後，以均衡資料的型態再進行穩定性分析，其對穩定性分析評價結果的影響，將用來檢視缺區估計法在區域試驗資料的適用性。結果得知，填入缺區估計值後使呈均衡資料再進行標準穩定性分析，雖然簡單，但因為會造成缺區品系之穩定性係數低估，故僅適用於穩定品系含少數一、二個缺區的場合，一旦缺區發生在不穩定品系時，容易使原來不穩定品系被誤認為是穩定。Crop regional trials were conducted for the purpose of selecting varieties with high yields and stability. Linear regression analysis is the most common and useful method to evaluate the adaptation of a quantitative character to the change of environments. However, a major practical limiation to date, stability analysis have been a requirement of no missing data, that is, data for every genotype and environment combination or treatment have been necessary. The precision of stability analysis can be unduly influenced by removing all the data of the genotypes or environments which contain missing plot, because of the reduction in number of genotypes and environments. In this study, a balanced dataset was obtained by substituting the missing values with the estimated ones, then one used the standard stability analyses for this assumed balanced data. The effect of missing-plot estimation on stability analysis was investigated to test its applicability in regional trial data. Results showed that the method was easy to use and involved a stable genotype with just one or two missing observations. An unstable genotype might be wrongly regarded as stable because that missing-plot estimation yielded a below-estimation of stability index when missing data occurred in an unstable genotype