溫度與光對青花菜花芽分化的影響

Abstract

臺灣中南部冬季冷涼乾燥氣候適合青花菜(Brassica oleracea L. var. italica)採種，為拓展溫帶地區市場需引入具耐寒性的種源，此類種源一般為低溫需求較強的晚生或極晚生種，所以其誘導開花為一重要課題，本試驗探討光週期及光質對青花菜花芽分化的影響。育苗光週期14/10 h處理相較12/12 h處理可顯著提升早生 ‘TSS AVRDC No. 2’ 及中生 ‘B75’ 青花菜的春化需求，後續選用光週期14/10 h作為育苗條件。15/10 oC春化處理10天可達到縮短播種至花芽分化所需天數(Days to apex transition, DTAT)的效果，且隨環境溫度提升，春化效果也越顯著。無春化處理之對照組，兩參試品種之DTAT皆顯著延遲，甚或維持營養生長態至定植後第120天仍未花芽分化。定植後的光質條件，紅光比例42%之高紅光比例光源(HR, R:FR=13.0)相較紅光比例34%的低紅光光源(LR, R:FR=2.6)也可顯著縮短DTAT，效果亦隨環境溫度提升而越顯著。此外，‘TSS AVRDC No. 2’ 的春化、HR光質及栽培溫度三個複因子分析具有交感關係。春化處理與HR光質處理對兩參試品種縮短DTAT的效果趨勢相當類似，且在春化處理下HR對DTAT縮短的效果(DSE-HRV)與在HR處理下春化處理對DTAT縮短的效果(DSE-VHR)相似，推測兩因子間有交互作用且可能相互取代。本試驗推測春化及HR光質雙重處理可更有效的調控青花菜開花，但對晚生及極晚生種的影響仍待進一步試驗證明。

The cool and dry weather in winter of southern Taiwan provides a good condition for broccoli (Brassica oleracea L. var. italica) seed production. To broaden the seed market to temperate countries, it’s necessary to introduce some cold-tolerance germplasm into the breeding program. However, such plant materials often accompany the character of late and/or very late maturity having strong cold requirement for flowering. Therefore, flower inducing in late and/or very late maturity cultivars or varieties become an important issue in southern Taiwan. The objective of this study is to evaluate the effect of seedling photoperiod and light quality on the floral initiation of broccoli. The vernalization requirement of early maturity ‘TSS AVRDC No.2’ and medium maturity ‘B75’ was significantly higher with seedling nursing photoperiod 14/10 h than with 12/12 h. Therefore, the nursing photoperiod 14/10 h was choosing for following studies. Ten days of vernalization treatment (15/10oC) significantly shortened the days from sowing to apex transition (DTAT) and the shorten effect was more significant as temperature increased. Without vernalization treatment, the delay of DTAT increased as temperature increased in ‘TSS AVRDC No.2’ and ‘B75’ tended to remain in vegetative growth till the end of experiment in higher temperature. The DTAT also shortened while grown under HR (High red light proportion light source, R/FR=13.0, red light proportion 42%) than LR (Low red light proportion light source, R/FR=2.6, red light proportion 34%) light source, and the shorten effect was more significant while ambient temperature elevated. In ‘TSS AVRDC No.2’, the vernalization, light quality and obligate temperature were interacting between each other. The DTAT shorten effect (DSE) of HR under vernalization (DSE-HRV) and the DSE of vernalization under HR (DSE-VHR) was similar. A possible explanation of the similarity was that these two factors have interaction and might be replaced between each other. Therefore, we concluded that the controlling of broccoli flowering can be more promising if a combination treatment of vernalization and HR light quality can be applied. However, the effect on cultivars of late and very late maturity should be tested.