天然物作為紅豆(Vigna angularis)生產時乾燥劑之可行性評估

紅豆 (Vigna angularis) 為台灣重要的雜糧作物之一，主要的栽培地區為高雄及屏東，109年台灣種植面積為6,290公頃，總產量為12,784公噸。為了配合機械採收作業，農民需要在收穫前噴灑除草劑作為乾燥劑噴灑於紅豆植株，使其快速且一致的落葉及乾燥，才不會卡住收穫機而影響收成效率及籽粒品質。過去大多使用巴拉刈 (Paraquat) 作為主要的乾燥劑，雖然價格便宜且乾燥效果佳，但其毒性極強。為了促進永續農業發展，人們開始研究是否有替代方案，以減少化學農藥的使用。本研究以紅豆作為材料，並選用3種天然物，以3種濃度的乳酸 (Lactic acid) 、丁香油 (Clove oil) 及香茅油 (Citronella oil) ，與目前紅豆常用的乾燥劑壬酸 (Pelargonic acid) 混合處理，分別於紅豆植株營養生長期及黃熟期進行施用，觀察並紀錄植株葉、莖、莢含水率、葉片受損率及黃化程度指數的變化，以評估不同濃度天然物對紅豆乾燥的影響。結果發現在紅豆營養生長期時以26%的乳酸、30%的丁香油及香茅油處理後，有顯著降低紅豆葉含水率及莖含水率並顯著的提高葉片受損率及黃化程度指數。而在紅豆黃熟期時以16%以上的乳酸、20%以上的丁香油及香茅油並混合5%及3.3%的壬酸處理時，對於紅豆葉含水率、莖含水率及莢含水率皆有顯著的降低，並且有顯著的提高黃化程度指數。本試驗的結果顯示這些處理對於紅豆植株有顯著的乾燥效果，提供農民除了化學乾燥劑以外，多個有效的天然物作為高屏地區的紅豆收穫使用。

關鍵字

紅豆；乾燥劑；乳酸；丁香油；香茅油

並列摘要

Adzuki bean (Vigna angularis) is one of the most important crops in Taiwan.The main production areas are Kaohsiung and Pingtung counties. In Taiwan,the planting area and yields of Adzuki bean are 6,290 hectares and 12,784 Mg in 2020. To use the mechanical harvester, it is necessary to spray herbicide as desiccants on the plants before harvesting to make the leaves fall consistently and dry quickly, which won’t jam the harvester and affect the efficiency and grain quality. In the past, Paraquat was used as the main desiccant. Although the Paraquat is cheap and high efficient, it is very toxic. To promote the development of sustainable agriculture, more research have begun on if there are other ways to reduce the use of chemical herbicide. This study used Adzuki bean as materials and applied three concentrations of lactic acid, clove oil, citronella oil and mixed pelargonic acid on the plant during vegetative and beginning maturity phase. The change of leaf water content, stem water content, and pod water content, leaf damage rate and yellowness index of plants were measured and analyzed, in order to find effective natural herbicides for the Adzuki bean harvesting. The results show that the leaf water content and stem water content were decreased significantly and leaf damage rate and yellowness index were increased significantly as affected by 26% lactic acid, 30% clove oil and 30%citronella oil during vegetative phase. Also, the leaf water content, stem water content and pod water content were decreased significantly and yellowness index were increased significantly as affected by at least 16%lactic acid, 20% clove oil and 20% citronella oil mixed pelargonic acid during beginning maturity phase. Our results indicated that these ways were significantly effictive for plant desiccation. Except for the chemical herbicides, farmers can choose more effective natural products for harvesting Adzuki bean in Kaohsiung and Pingtung counties.