Institute for Horticultural Production Systems, Leibniz-University Hannover, Hannover, Germany.
School of Food and Nutritional Sciences (SOFNUS), Jomo Kenyatta University of Agriculture and Technology, Nairobi, Kenya.
PLoS One. 2023 Sep 1;18(9):e0291129. doi: 10.1371/journal.pone.0291129. eCollection 2023.
The mango cultivar 'Apple' is an important fruitcrop in Kenya, but it is highly susceptible to russeting. The objective was to establish whether lenticels predispose cv. 'Apple' mango to russeting. Fruit mass and surface area increased in a sigmoidal pattern with time. The frequency of lenticels per unit surface area decreased during development. The number of lenticels per fruit was constant. Lenticels were most frequent in the apex region and least common in the cheek and nak (ventral) regions. The cheek region also had lenticels with the largest core areas, whereas the lenticel core areas in the apex region were significantly smaller. Microscopy revealed stomata became covered over with wax deposits at 33 days after full bloom (DAFB). By 78 DAFB, periderm had formed beneath the pore. At 110 and 161 DAFB, cracks had developed and the periderm had extended tangentially and radially. The presence of lenticels increased the strain released upon excision of an epidermal segment, further strain releases occurred subsequently upon isolation of the cuticle and on extraction of the cuticular waxes. The number of lenticels per unit surface area was negatively correlated with the fruit surface area (r2 = 0.62 **), but not affected by fruit size. Mango cv. 'Apple' had fewer, larger lenticels and more russet, compared with 'Ngowe', 'Kitovu' or 'Tommy Atkins' mango. In cv. 'Apple', the lowest lenticel frequency, the largest lenticels and the most russeting occurred at a growing site at the highest altitude, with the highest rainfall and the lowest temperature. Moisture exposure of the fruit surface resulted in enlarged lenticels and more microcracking of the cuticle. Our results establish that russeting in 'Apple' mango is initiated at lenticels and is exacerbated if lenticels are exposed to moisture.
“Apple”芒果是肯尼亚的一种重要水果作物，但它极易出现皱皮。本研究旨在确定是否气腔使“Apple”芒果容易出现皱皮。果实质量和表面积随时间呈“S”型增长。单位表面积上气腔的频率在发育过程中降低。每个果实的气腔数量保持不变。气腔在果顶最密集，在果侧和果脐（腹面）最稀疏。果侧气腔的核心区域最大，而果顶气腔的核心区域最小。显微镜观察发现，在盛花后 33 天（DAFB），气孔开始被蜡质沉积物覆盖。到 78 DAFB 时，皮孔下方已形成周皮。在 110 和 161 DAFB，裂缝已经出现，周皮已横向和径向扩展。气腔的存在增加了表皮段切除时释放的应变，随后在角质层分离和提取角质层蜡时，应变会进一步释放。单位表面积上气腔的数量与果实表面积呈负相关（r2 = 0.62 **），但与果实大小无关。与“Ngowe”、“Kitovu”或“Tommy Atkins”芒果相比，“Apple”芒果的气腔数量更少、更大，皱皮更多。在“Apple”芒果中，气腔频率最低、气腔最大且皱皮最多的部位出现在海拔最高、降雨量最大且温度最低的生长点。果实表面暴露在潮湿环境中会导致气腔增大和角质层微裂纹增多。我们的研究结果表明，“Apple”芒果的皱皮始于气腔，如果气腔暴露在潮湿环境中，皱皮会加剧。
