鳳梨日燒病之研究（I）鳳梨果皮溫度與日燒病發生之關條

Studies on Sunburn Disorder of Pineapple Fruits (I) Relationship between Exocarp Temperature of Pineapple Fruit and the Occurrence of Sunburn Disorder

1.鳳梨日燒現象為發育中的果實，受強烈日照，吸收過量熱能，灼傷果皮及果肉細胞組織，引起之生理病害。2.就果實方位而言， 日燒病主要發生在西面與東面之果皮；就果實部位而言，除倒伏植株外，直立植株日燒病大都發生在果肩部位。3.鳳梨果皮受熱，溫度上升至40°C以上，若持續維持3小時以上，便可能發生日燒現象。4.發育初期之果實，因果汁含量低，即使受相當的日照，仍不致發生日燒，隨著果實的發育，果汁含量逐漸增加，果皮受到陽光照射，熱能被果實內水份吸收，不易散失，長時間維持高溫，便發生日燒現象。5.紮葉於果實頂端，可減少受光時間，並降低果皮溫度，避免日燒現象的發生。

1. The occurrence of physiological disorder of sunburn on pineapple fruits is due to an excessive exposure of strong sunshine on exocarp or mesocarp tissues of growing fruits. 2. Sunburn occurrs mainly in west and east exocarps of a fruit and fruit shoulder in normal upright growing fruits. 3. If the fruit temperature exceeds 40°C and lasts more than 3 hours, the sunburn occurs. 4. The most young fruits which contain less juice are free from sunburn. However, the mature fruits containing more juice are easy to suffer under sunburn. This is supposed that the mature fruits contain more juice with higher sugar content which absorb much more solar energy and are easily to be heated up. 5. Leaf-bunching beyond the fruits lowers the fruit temperature and reduce the number of sunburned fruits.