愛文芒果果皮流膠病變發生原因之探討

Study on the Causes of Resinous Latex Burnt on the Fruit Peel of 'Irwin' Mango

張錦興(Chang, C. H.)

《臺南區農業改良場研究彙報》 68期 (2016/12) Pp. 1-14

摘要

愛文芒果是臺灣外銷主力果品之一，近年來發生流膠病變現象以致果實外觀不佳而降低選果率，為了探究其發生原因，本試驗模擬在果實生育期噴施藥劑，測試其對流膠病變發生之影響，試驗結果發現套袋前噴施磷酸氫一鉀（KH_2PO_4）等物質並無法增進果實肥大、甜度或色澤，卻促進流膠病變比率，嚴重時可高達90％，果污總數高達100％以上，說明芒果流膠、果污可由外在因素刺激引起。測量未套袋、套袋與溫室內之愛文芒果果實向陽面與背陽面日夜溫度變化，夜溫各處理間並無顯著變化，平均在25℃左右；但日溫溫室果實最高達36℃，較其它各處理高出5℃，流膠程度最嚴重，流膠率達100％，推測果實生育期日夜溫差過大是導致芒果流膠病變的原因之一。經果實表皮皮目發育切片觀察，果皮在花後56天前其組織結構細緻無明顯孔隙，之後出現細微的皮目孔隙而有明顯開裂，不論早花期或晚花期結的果實以KH_2PO_4處理其皮目孔徑較大，大於250 μm，致使發生流膠病變時期較早而且較為嚴重。因此，愛文芒果果實發育期在後期肥大時，若遇上高溫，或噴施外在營養物質則可能刺激果皮皮目增長、崩裂而促進流膠病變的發生，建議農民在田間操作時應注意花期的微調，同時亦應減少可能引起果皮皮目生長刺激物質的噴施，以避免其病變發生的風險。現有技術：農民為了增進果實肥大、促進果色與甜度，習慣在套袋之前多次噴施所謂營養物質，反而容易促進皮目增生，致使在後期果實肥大遭受擠壓、崩裂而發生流膠病變或果污的現象。創新內容：本研究分析相關果實上外施這些營養物質對芒果果實皮目發育與流膠病變的關係，其結果可用來調整農民田間操作模式。對產業影響：藉由花期的微調、減少外在營養物質噴施作業，可減少多種果皮外觀不佳的現象，增加選果率而提高農民收益，同時節省農民無謂的田間操作，減少資材與人力的浪費。

關鍵字

芒果 ； 皮目 ； 乳汁 ； 生理病變

並列摘要

A new disorder known as resinous latex burnt from lenticels of mango fruits in some orchards has been reported in Taiwan lately. The symptom caused the damage on fruit peel, and made those fruits not accepted by exporter. This experiment is attempted to explore the reason caused the resinous latex burnt on the fruit peel of Irwin mango. The surface temperature of mango fruits for and compared those are non-bagging, bagging in the open field and growing in greenhouse, were measured. It showed that the temperature both on the surfaces of fruit sunny face and shading face were no difference at night. But the day temperature for those fruits grow in greenhouse are the highest, up to 36°C or 5°C higher than those fruits growing in open field. Meanwhile, the resinous latex burnt rate was up to 100% on the fruits grown in the greenhouse. Those fruits sprayed with KH_2PO_4 0.1% before bagging caused a rate of 90% in resinous latex burnt the most serious rate of resinous latex sap and staining rate on the fruit peel when they were compare of to all the treatments, but it did not increase the fruit size, T.S.S. and improve the fruits peel color. Observed by microscope, the lenticels of Irwin mango fruit appeared at 56 days after blooming and the size up to 16 μm. Sap burnt from lenticels may begin at 77 days after blooming. But the fruits sprayed with KH_2PO_4 0.1% induced lenticels to appear earlier. Those lenticels size up to 250 μm and bigger than those fruits of the controls. We concluded that the temperature varied much from day to night at late development stage, or supplementary nutrient applications on the Irwin mango fruit both may seriously induce the resinous latex burnt on the fruit peel after early bagging-stage. What is already known on this subject? Supplementary nutrient applications by foliar sprays did not effectively increase fruit size, T.S.S. and peel color, but did increase the lenticels size. It makes the lenticels ease to burst up while the fruit grows up, and then cause the resinous latex burnt and stain on Irwin mango fruit peel. What are the new findings? This experiment is attempted to investigate the reason caused the resinous latex burnt on the fruit peel of Irwin mango. The result can be useful for farmers to regulate their cultivation practice to avoid resinous latex burnt. What is the expected impact on this field? By regulating the blooming stage or reducing the spray of what so called supplementary nutrient applications, the risks for damage on appearance of mango fruit could actually be reduced. Meanwhile, the labor and material used in cultivation also could be saved quite a lot by this way.

並列關鍵字

Mango ； Lenticels ； Latex ； Physiological disorder