結球白菜高溫淹水耐受性之篩選及生理反應

Abstract

結球白菜(Brassica campestris L.spp. pekinensis)為十字花科蕓苔屬之冷涼季蔬菜，生長適溫為10~22℃，耐熱品種可於平均氣溫持續超過25oC下正常發育、形成緊實葉球。臺灣夏季高溫，且常有颱風、豪雨侵襲，影響蔬菜生產，民國98年結球白菜損失金額約為3000萬臺幣。本研究先調查結球白菜40品種夏作淹水試驗之產量，並選出耐受性不同之品種，探討其苗期於高溫40/30℃淹水逆境下生長與生理之差異。依據結球白菜40品種夏作田間淹水產量試驗，篩選出產量較高的‘慶農200號’與AV86188，產量次高之‘桃園亞蔬2號’、‘47號’與農友‘玉豐’，及產量最低之‘瑞農720’等6品種，於20/15℃生長箱中育苗3週，即予以40/30℃淹水、40/30℃不淹水、20/15℃淹水及20/15℃不淹水共4種處理各48小時，之後調整至20/15℃並排水作為恢復期。於恢復期第8天，‘桃園亞蔬2號’、‘47號’與‘瑞農720’高溫不淹水與高溫淹水處理之葉面積、鮮重或乾重顯著下降，而‘慶農200號’與農友‘玉豐’有較好的生長勢。‘47號’與‘瑞農720’在高溫逆境下，電解質滲漏比率(electrolyte leakage ratio)顯著升高。高溫不淹水逆境對葉綠素含量的影響較嚴重，高溫逆境皆影響新生葉片之葉色。高溫逆境下6品種之葉綠素螢光參數Fv/Fm值皆顯著下降，於回復期第2天回升，但AV86188與‘瑞農720’之光合速率在恢復期第4天仍顯著低於對照組，其氣孔導度與蒸散速率也有相似之趨勢。對高溫淹水敏感之‘瑞農720’於高溫淹水處理下之脂質過氧化物丙二醛(malondialdehyde)與總過氧化物(total peroxide)含量皆顯著高於耐受品種‘慶農200號’，‘慶農200號’之脯胺酸(proline)含量在逆境處理後24小時即顯著累積較多達1.1 μmol/g。‘慶農200號’高溫不淹水與高溫淹水處理之過氧化氫酶(catalase)活性在處理後48小時顯著升高，‘瑞農720’則無顯著差異；抗壞血酸過氧化酶(ascorbate peroxidase)活性以‘慶農200號’高溫不淹水處理提升最快。根據試驗結果，夏作淹水後產量不同之品種，其苗期於高溫40/30℃淹水逆境下之鮮重、乾重、丙二醛含量、脯胺酸含量與CAT活性表現互相對應，或具有作為結球白菜高溫淹水耐受性篩選指標之潛力。

Chinese cabbage (Brassica campestris L. spp. pekinensis) is a cool-season vegetable of Brassica species in Cruciferae family. Chinese cabbage is not suitable to cultivate in summer of Taiwan due to the optimal growth temperature being 10~22℃. Heat tolerant Chinese cabbage cultivars can grow and develop a tight head at average temperature over 25℃. However, high temperature, typhoon and heavy rainfall affect vegetable production in summer of Taiwan. The loss sum of Chinese cabbage in 2009 was about NT$30,000,000. In this research, tolerances of 40 Chinese cabbage cultivars to waterlogging in summer were studied. The seedling growth and physiology of cultivars with very different tolerances to heat and waterlogging were investigated. According to the field yields after waterlogging in summer, the highest yielding ‘Ching-Long 200’ and AV86188, higher yielding ‘ASVEG#2’,‘No. 47’ and ‘Yu-Fong’, and the lowest yielding ‘Ruey-Long 720’ were selected from 40 cultivars. These six cultivars were sown and grown in growth chamber under20/15℃for 3 weeks. Then seedlings were treated with 20/15℃ non-waterlogging, 20/15℃waterlogging, 40/30℃ non-waterlogging and 40/30℃waterlogging. Afterwards seedlings were transferred to 20/15℃and drained as for recovery stage. On the 8th day of recovery, the leaf area, fresh weight and dry weight of ASVEG#2’, ‘No. 47’ and ‘Ruey-Long 720’ were significantly lower after heat and waterlogging treatments. ‘Ching-Long 200’ and ‘Yu-Fong’ showed better seedling growth. The electrolyte leakage ratio of ‘No. 47’ and ‘Ruey-Long 720’ increased significantly under heat stress. The 40/30℃ non-waterlogging treatment affected the chlorophyll contents of Chinese cabbage seriously. Heat stress also affected the leaf color of new born leaves. Fv/Fm values of 6 cultivars decreased significantly under heat stress and raised on the 2nd day of recovery. However, the photosynthetic rates of AV86188 and ‘Ruey-Long 720’, as stomatal conductance and transpirational rate, were significantly lower than control on the 4th day of recovery. The malondialdehyde and total peroxide contents of heat and waterlogging sensitive ‘Ruey-Long 720’ were significantly higher than tolerant ‘Ching-Long 200’ after heat and waterlogging treatment. The proline content of ‘Ching-Long 200’ accumulated to a significantly higher value of 1.1 μmol/g after 24hour stress treatment. The catalase activity of ‘Ching-Long 200’ significantly increased after 48 hours of both non-waterlogging and waterlogging at 40/30℃treatment, while ‘Ruey-Long 720’ did not show significant difference. The activity of ascorbate peroxidase of ‘Ching-Long 200’ increased earlier after 40/30℃ non-waterlogging treatment. According to these results, the expression of fresh weight, dry weight, malondialdehyde and proline contents, and catalase activity of seedlings were similar to the yield of waterlogging trials in summer. These parameters might have potentials as screening index for heat and waterlogging tolerance of Chinese cabbage.