結球白菜耐熱田間性狀及篩選指標評估

結球白菜(Brassica rapa L. subsp. pekinensis )屬於溫帶蔬菜，溫度高於25℃時，結球困難，夏季為臺灣生產空窗期。本研究篩選出稼穡種苗公司提供之結球白菜‘CA6522’ 具早生特性之結球白菜F1品種，定植約40-45天即可採收，頂燒症發生率低，在臺灣南部四季皆可收穫葉球，其中以冬季葉球最重，球重760 g，但仍較其他商業品種輕，在9至10月期間平均最低溫21.5℃仍可滿足春化需求抽薹。本研究以‘CA6522’作為育種起始材料，欲選出優良早生自交系，以應用在組合耐熱結球白菜F1品種，試驗同時亦評估結球白菜耐熱田間性狀及細胞膜熱穩定性，以選出可用之耐熱篩選指標。在2019年在結球白菜‘CA6522’F2分離族群中具快速結球、無頂燒及提早抽薹性狀的單株中，挑選出10株可在定植後第28天形成硬實葉球的優良單株進行世代推進。2020年，選出自交不親和性強之兩F2單株，19-CA6522-F2-3與19-CA6522-F2-9進行世代推進並選出2可在高溫下快速結球的優良F3單株，19-CA6522-F2-3-9與19-CA6522-F2-3-15，以供世代推進及試交。結球白菜夏季品種間田間結球率分別與細胞膜熱穩定性及葉片厚度具高度相關性，與SPAD值則無相關性，但在‘CA6522’分離族群間則顯示此二指標與田間結球表現不顯現相關性。此外，單株定植後第14天的葉片寬度與結球速度具相關性，其可應用性仍待後續確認。

關鍵字

結球白菜；耐熱性；田間性狀；細胞膜熱穩定性；育種

並列摘要

Chinese cabbage (Brassica rapa L. subsp. pekinensis) is a temperate vegetable. Heading could be hindered when the temperature is above 25℃, and as the result summer production is a problem in Taiwan. An early maturity F1 Chinese cabbage variety ‘CA6522’ was selected as the starting material in this study. Obtaining early maturity inbred lines and develop selection indicator for heat tolerant was the ultimate goal in this study. Heads of ‘CA6522’ can be harvested within 40-45 days after transplanting and able to produce heads all year round in southern Taiwan. In addition, the average weight of the heads is 760 g in winter production and lower in other seasons. ‘CA6522’ was able to bolting under the period of the average minimum temperature 21.5℃ between September and October. In 2019, 10 quick heading individuals were selected to generate F3’s, showing no tipburn and early bolting characters, were selected from the Chinese cabbage ‘CA6522’ F2’s. The quick heading was defined as forming a firm head on the 28th day after transplanting. Among the selected lines, 19-CA6522-F2-3 and 19-CA6522-F2-9 showed strong self-incompatibility were selected, and their derived F3 individuals, 19-CA6522-F2-3-9 and 19-CA6522-F2-3-15, were selected to developing advance generation and testcross. The quick heading under high temperature summer was highly correlated with cell membrane thermostability and leaf thickness, but has no correlation with the SPAD value in in Chinese cabbage cultivars of different maturities. However, the correlation was not existed in the F2 segregation population of ‘CA6522’. The leaf width at 14th days after transplanting was found to correlate with quick heading instead and further confirmation will be proceeded in the following generation.