| 摘要： 紅龍果主要產季在高溫多雨的夏季，同時也為多種病害最適的發病環境，若果實在進入冷鏈前未妥善處理，常因病害之故造成損失，如由Alternaria spp.引起的褐斑病、Gilbertella persicaria 引起的濕腐病等採後病害，係短程內銷與長程外銷最大的限制因子之一，也是紅龍果冷鏈運銷上亟需解決的問題。為防治紅龍果採後病害，目前多以採收後處理為主要手段，然而可能會影響果實品質或仍不足以大幅遏止病害發生。根據農業試驗所的初步調查，台灣部分產區生產的果實在模擬長途冷藏貯運（4-5℃，3 週）後，果實平均損耗率在出庫當天達15%以上，櫥架後（22℃，3 天）達60%左右，且絕大多數（95%以上）為病害引起的耗損。生態調查結果顯示，多種病原菌，包括Alternaria spp.在內，在紅龍果幼果至少2 週大時即存在果實表面，可能伺機感染果實；進一步人工試驗結果顯示，褐斑病可能為潛伏感染，顯示病害防治應提早於田間開始。個別測試田間防治或採後處理防治效果，包括(1)幼果期套袋、(2)幼果期開始施以藥劑直至成熟，以及(3)採收後浸泡次氯酸水等，藉以初步獲得適合使用之資材與使用條件，而果實經模擬貯運後損耗率各可降低5%-20%左右不等。於田間測試「整合之田間防治至採後前處理」管理技術1 式，施用方式包括：開花結果後施用藥劑（「非化學合成藥劑組」施用黑修羅（農業試驗所開發之商品，肉桂精油微乳劑）、「化學合成藥劑組」施用亞托敏；共各施用2-3 次），隨後配合「結果7 至10 天後套袋」與「採後浸泡合適條件的次氯酸水」，待果實成熟採收後調查模擬貯運後損耗率。無論化學合成或是非化學合成藥劑組，貯運後損耗率可穩定降低20%以上，且用藥次數亦可降低。The main production season of pitaya (red dragon fruit; Hylocereus spp.) is in the hot and rainy summer, which is also suitable for many diseases to develop. If the fruit is not properly handled before entering the cold chain, losses are often caused due to diseases, such as brown spot caused by Alternaria spp., wet rot caused by Gilbertella persicaria and other post-harvest diseases. These post-harvest diseases cause problems and is needed to be solved urgently in the cold chain transportation and sales of pitaya, and it is one of the limiting factors for both short-range domestic sales and long-distance foreign sales. The currently main method to prevent post-harvest diseases of pitaya is by postharvest treatment, but it might affect the fruit quality during the handling process, or it is not enough to obviously prevent the occurrence of diseases. According to our preliminary investigations, the average loss rate of pitaya fruits, which were produced during production season in some areas in Taiwan, were about 15% after the simulated long-distance transportation (4-5OC, 3 weeks), and reached to about 60% on the shelf(22OC, another 3 days), and most of the loss, above 95%, were caused by postharvest diseases. The ecological survey results showed that a variety of pathogens, including Alternaria spp., existed on the surface of young fruit since at least 2 weeks after fruiting and might be waiting for the opportunity to infect the fruits; further artificial infection test showed that brown spot disease might act as latent infection disease on pitaya fruits, suggesting that disease management should start earlier in the field. Individual effects of strategies for disease control were evaluated separately, including(1)bagging the fruit at young stage, (2)applying chemicals at the young fruit stage until maturity, and (3)soaking the fruits in hypochlorous acid water after harvesting etc. Appropriate materials and usage conditions are initially obtained, and the loss rate of the treated fruits were found reduced by less than 10% or around 20%, depending on the treatments, after simulated long-distance transportation and then on the shelf. Subsequently, the "integrated field control to post-harvest pre-treatment" management technology was actually tested in the field. The implied methods include applicating of agents after flowering and fruiting ("non-chemical treatment group" used Black Asura, a microemulsifier of cinnamon essential oil, as applied agent while “chemical treatment group” used azoxystrobin; a total of 2-3 times each), bagging the young fruits 1 week after fruiting and then soaking the fruits in hypochlorous acid water with appropriate conditions after harvesting. After the simulated storage and transportation, the loss rates of all treated fruits were stably reduced by more than 20%, and the number of agent application times were also reduced. |
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