Fruit Thinning and Physiological Disorders in Citrus Variety ‘Harumi’

Abstract

Citrus 'Harumi' is a mandarin-type cultivar and shows a wide range of fruit size, which affects fruit quality such as sugar and acid contents. In citrus, fruit size also affects the degree of physiological disorder which become a big problem during storage. Thus, making fruit with equal and appropriate size is very important. Fruit thinning is one of the most important techniques to adjust fruit size by controlling the fruit number. Basically, fruit thinning has been conducted using a criterion based on leaf and fruit ratio (L/F) or fruit number per canopy volume. In this review, several thinning criteria for 'Harumi' and other citrus varieties are compared, and the pros and cons are discussed. In some citrus varieties, storage is necessary to adjust shipping time. During the storage, some physiological disorders occurred in peel, flesh and whole fruit. The occurrence of physiological disorders was influenced by citrus variety, fruit size and environmental conditions during storage. In 'Harumi' which is classified to easy-peeling variety, small fruit showed serious weight loss and peel wrinkle, while rind puffing and dehydration of flesh were big problems in large fruit during storage. Polyethylene (PE) bag wrapping has been used to decrease the fruit weight loss and to prevent the occurrence of some physiological disorders in tightskin citrus varieties. However, the influences of PE wrapping on easy-peeling citrus is unclear. In this study, the researches on storage conditions, feature, and cause of physiological disorders during storage are also reviewed, and the effects of PE wrapping are discussed to improve storage condition in 'Harumi'.

Identification of Photosynthesis Characteristics and Chlorophyll Metabolism in Leaves of Citrus Cultivar (Harumi) with Varying Degrees of Chlorosis

“…Citrus fruits are rich in bioactive substances, such as essential oils, carotenoids, flavonoids, acacia and limonoids, which have significant effects in terms of anti-inflammation, anti-oxidation, immune regulation, prevention and treatment of multiple respiratory diseases [3,4]. Harumi, which is a late-maturing hybrid citrus ['F 2432' Ponkan (Citrus reticulata) × Kiyomi tangor (Citrus unshiu × Citrus sinensis)] [5], has been increasingly planted in China and favored by many consumers because of its high quality, high yield and abundant nutrients [6]. However, after years of field observation, we found that citrus (Harumi, Daya, etc.)…”

Transcriptome analysis of Harumi tangor fruits: Insights into interstock-mediated fruit quality

“…‘Harumi’ ( Citrus reticulata × Citrus sinensis ) is a late-ripening cultivar that produces an oblate-shaped fruit; the rind color is orange and the fruit is easy to peel. The fruit ripens in January ( Takishita et al., 2021 ). This cultivar has been increasingly planted in China and is favored by many consumers because of its taste, high yield, and abundant nutrients ( Dong et al., 2020 ).…”