青花菜耐熱性探討

Abstract

青花菜為溫帶作物，適合冷涼環境種植，臺灣夏季高溫常導致青花菜不結花球或花球品質不良。由亞蔬-世界蔬菜中心育出的青花菜品系(種)AV515、‘種苗亞蔬1號’及‘種苗亞蔬2號’，具有早生與耐熱的特性。於21/15 ℃育苗，需28.28±0.24天、30.68±0.23天及31.17±0.22天達五片真葉，生長速率為熱敏感品種‘B75’的1.13-1.25倍。具五片真葉之健壯苗經高溫35/25℃處理2天，‘種苗亞蔬2號’的葉片相對熱傷害值為17.80±1.81，僅‘B75’的40%。五片真葉健壯苗接受光週期12/12 hr與15/10 ℃低溫的春化5天後，耐熱品系(種)AV515、‘種苗亞蔬1號’及‘種苗亞蔬2號’需33.3-34.5天進入生殖生長，其莖頂分生組織轉變為花序分生組織之日數隨春化天數的增加而提高。調整春化溫度至18/13℃仍具春化效果，但提高莖頂分生組織轉變為花序分生組織之日數；改變光週期至14/10hr，則會降低莖頂分生組織轉變為花序分生組織之日數9-14天，並減少葉片數5-7片，相對地，‘B75’較不受光週期改變所影響。春季露天栽培密度50×50 cm2與25×50 cm2之花球性狀差異不大。夏季設施栽培‘B75’之逆春化率達100%，三耐熱品系(種)的逆春化率則分別為5.56%、6.25%及5.56%；春化溫度對夏季花球直徑、花蕾厚度與花球重有顯著影響。秋季設施栽培密度不影響定植至採收日數(DTH)，定植於25×25 cm2之平均花球直徑皆大於9 cm，但較25×50 cm2的花球直徑減小約30-20%、球重減小約60-40%；春化溫度對秋季定植至採收日數、平均花球直徑等花球特徵影響不顯著，但花球重與側生枝條受春化溫度影響。此外，不同定植時間對耐熱品系(種)AV515、‘種苗亞蔬1號’及‘種苗亞蔬2號’之生長發育性狀亦有顯著地影響，夏季設施栽培之植株與花球性狀皆較春、秋季植株小，唯結球葉片數不受季節改變。

Broccoli (Brassica oleracea var. italica) is temperate vegetable. The high summer temperature in Taiwan often leads to fail-heading or quality reduction. AVRDC - The World Vegetable Center had developed the broccoli line (variety) AV515, ‘TSS AV No.1,’ and ‘TSS AV No.2’ with characteristics of early maturity and heat resistance. It took 28.28±0.24, 30.68±0.23 and 31.17±0.22 days up to five leaves when nursering at 21/15 ℃, which is1.13-1.25 times longer than that of heat-sensitive variety ‘B75’. After high temperature 35/25 ℃ process for two days, five leaves seedlings of ‘TSS AV No.2’ had lowest RI value of 17.80 ± 1.81, only 40% of the ‘B75’. When vernalized with 15/10 ℃ and 12/12 hr photoperiod for 5days, AV515, ‘TSS AV No.1,’ and ’TSS AV No.2’needed 33.3-34.5 days to enter the reproductive growth; the days of shoot tip meristem into inflorescence meristem increases with vernalization days. Vernalization was still effective when higher the temperature to 18/13 ℃, but which increased the days of shoot tip meristem into inflorescence meristem. Changing the photoperiod to 14/10hr, on the other hand, was to decrease the days of shoot tip meristem into inflorescence meristem in 9-14 days and reduced 5-7 pieces of leaves. However, we found that ‘B75’were less sensitive to the photoperiod change. Head traits in spring were not significant between the growing spacing of 50×50 cm2 and 25×50 cm2. In summer facility cultivation, ‘B75’ had 100% anti-vernalization plants; nevertheless, three heat-tolerance lines (variety) were5.56%, 6.25% and 5.56%, respectively. Significant effects on the head diameter, the curd thickness, and the head weight were shown in different vernalization temperatures of summer facility. Growing spacing in autumn affected the head diameter but not the DTH. The average head diameter grown in spacing 25×25cm2 were larger than 9 cm but still20-30% smaller than that in spacing 25×50 cm2,and the head weight was also about 40-60% lighter. The vernalization temperature change, by contrast, was not significant to DTH and head diameter, but was effective on head weight and lateral branches. In addition, it had a significant impact on heat-tolerance line (variety)AV515, ’TSS AV No.1,’ and ‘TSS AV No.2’ in different planting time. In comparison of vegetative and head characters, the autumn and winter growing heat-tolerance line (variety) showed much more vigorous than the summer growing plants, except the leaf number at curding.