Russeting in ‘Apple Mango’: Causes, consequences and management

褐变是一种重要的果实表面病害，在世界范围内生长的许多水果作物中。这包括“苹果”芒果，这是一种具有相当大的市场潜力的芒果品种，但由于经常发生赤霉病和赤霉病果实的视觉外观差，目前尚未开发。该项目的目标是确定肯尼亚苹果芒果赤褐色的机理基础，并制定适当的对策。本研究将探讨并验证下列假说三：（1）苹果芒果的褐变是由表皮的显微破裂及周壁的形成所导致。(2)“苹果”芒果微裂纹的形成是由于生长应力引起的表面膨胀和角质层沉积的不匹配。此外，水果表面的水分会加剧微裂纹。由于增加的皮肤对水蒸气的渗透，所得的锈色“苹果”芒果在收获后皱缩（Khanal等人，2019年）。(3)通过套袋防止果实表面水分和使用GA应用的底层细胞层加强角质层的结构支撑，降低了'苹果'芒果对赤霉病的易感性，而不影响果实品质。该项目预计将为赤霉病的形成以及赤霉病对'苹果'芒果和许多其他水果作物采前和采后性能的影响提供基本的见解。深入了解果锈发生的机理，有助于制定有效的管理策略，减少果锈，提高苹果芒果在肯尼亚的市场竞争力。

Russet is an important fruit surface disorder in many fruit crops grown worldwide. This includes ‘Apple’ mango, a mango variety that has considerable market potential, but that is currently not exploited due to the frequent occurrence of russet and the poor visual appearance of russeted fruit. The objective of the project is to identify the mechanistic basis of the russet in ‘Apple’ mango in Kenya and to develop appropriate counter strategies. The following hypothesis three will be investigated and tested: (1) Russet in ‘Apple’ mango is preceded by microscopic cracking of the cuticle and formation of a periderm. (2) Formation of microcracks in ‘Apple’ mango is due to growth stress resulting from a mismatch of surface expansion and cuticle deposition. In addition, moisture on the fruit surface aggravates microcracking. The resulting russeted ‘Apple’ mango shrivels postharvest due to increased skin permeance to water vapor (Khanal et al., 2019).(3) Preventing surface moisture by bagging of fruit and strengthening the structural support of the cuticle by underlying cell layers using GA application decreases russet susceptibility of ‘Apple’ mango without compromising fruit quality.The project is expected to provide fundamental insight into russet formation and the effects of russet on pre- and postharvest performance in ‘Apple’ mango and many other fruit crop species. A better understanding of the mechanism of russet is helpful in developing effective management strategies to reduce russet and to improve marketability of ‘Apple’ mango in Kenya.