洋桔梗葉片頂燒相關的環境因子與植株發育之研究

Studies on Leaf Tipburn Associated Environmental Factors and Plant Development of Eustoma grandiflorum

王信文(Hsin-Wen Wang) ； 魏子耀(Tzu-Yao Wei) ； 葉德銘(Der-Ming Yeh)

《臺灣園藝》 67卷3期 (2021/09) Pp. 131-146

摘要

設施內生產洋桔梗［Eustoma grandiflorum (Raf.) Shinn.］切花，常見葉片頂燒（leaf tipburn）之缺鈣生理障礙，但出現此症狀的環境因子與植株生長發育狀況並不完全清楚。本研究取具有5對完全展開葉、營養生長之洋桔梗‘國王淡紫’（'King of Orchid'），分別置於高溫（36/23℃處理14天）或涼溫（25/18℃處理35天）搭配74%或91%相對濕度（relative humidity, RH）之人工光照室，結果顯示植株於91% RH處理下，於花芽創始期間植株出現葉片頂燒。相較於74% RH處理，91% RH處理之葉片蒸散速率與葉脈密度較低。當蒸氣壓差（vapor pressure deficit, VPD）介於1.08-2.62 kPa時之蒸散速率最高且維持穩定，VPD低於1.08 kPa時則蒸散速率隨VPD降低而下降。當植株花芽創始後如遇數天RH太高（＞ 73%-75% RH）或VPD太低（＜ 0.83-1.02kPa）之環境，則頂燒發生率會顯著較高。每周噴施二次25 mM氯化鈣溶液可減輕頂燒發生率，而每天噴施25 mM，以及每天噴施與每周噴施二次50或100 mM氯化鈣溶液等處理無葉片頂燒發生，但於100 mM氯化鈣處理中觀察到葉面出現大面積之白化。

關鍵字

葉脈 ； 莖頂發育階段 ； 蒸散速率 ； 蒸氣壓差

並列摘要

Leaf tipburn of Eustoma grandiflorum (Raf.) Shinn. is a calcium-deficient disorder commonly seen under protected production. A better understanding of environmental factors and plant development status would facilitate the cause and solution to the incidence of tipburn. Vegetative seedlings of Eustoma 'King of Orchid' with 5 leaf-pairs were grown in phytotrons at day/night temperatures of 36/23℃ (for 14 days) or 25/18℃ (for 35 days) both under 74% and 91% relative humidity (RH) conditions. Results showed that, regardless of temperature, young expanding leaves below flower primordia expressed tipburn symptoms in plants under 91% RH but not 74% RH. The 91% RH treatment led to a low transpiration rate (E) and vein density of young expanding leaves. At constant leaf temperature, E declined as vapor pressure deficit (VPD) decreased from ca. 1.08 kPa, while E remained consistently high when VPD ranged from 1.08 to 2.62 kPa. Tipburn incidence might occur within a few days and tipburn severity increased in flower-initiated plants under high RH (＞ 73%-75%) or low VPD (＜ 0.83-1.02 kPa) conditions. Spray of 25 mM CaCl_2 solution twice per week for two weeks reduced tipburn incidence, and no tipburn was observed when pla nts were sprayed daily or twice per week with 50 or 100 mM CaCl_2 solution for two weeks. However, leaf phytotoxicity, expressed as bleaching, was observed in 100 mM CaCl_2 treatments.

並列關鍵字

leaf vein ； shoot apical stage ； transpiration rate ； vapor pressure deficit