Outcrossing Levels and Fruit Quality in Single-Cultivar Blocks of a Multi-Cultivar Lychee (<i>Litchi chinensis</i> Sonn.) Orchard

Intraspecific diversity is often introduced in orchards to promote cross-pollination, which is essential for self-incompatible crops and beneficial for many self-compatible crops. In lychee, orchards are often planted with multiple cultivars to increase the availability of male flowers, enhancing po...

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Bibliographic Details
Main Authors: Stephen J. Trueman, Joel Nichols
Format: Article
Language:English
Published: MDPI AG 2025-02-01
Series:Horticulturae
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Online Access:https://www.mdpi.com/2311-7524/11/3/244
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Summary:Intraspecific diversity is often introduced in orchards to promote cross-pollination, which is essential for self-incompatible crops and beneficial for many self-compatible crops. In lychee, orchards are often planted with multiple cultivars to increase the availability of male flowers, enhancing pollen transfer to female flowers. Typically, this diversity is arranged in single-cultivar blocks, requiring pollinators to transport cross-pollen across rows to reach trees in the middle of each block. We aimed to determine the levels of outcrossing at the edge and in the middle of blocks of Fay Zee Siu, Kaimana, Kwai Mai Pink, Sah Keng, Souey Tung and Wai Chee in a multi-cultivar lychee orchard. We also aimed to determine whether outcrossed fruit have different mass, skin colour and flavour attributes from selfed fruit. All cultivars produced a mixture of outcrossed and selfed fruit. Fay Zee Siu and Kaimana fruit were predominantly outcrossed, Kwai Mai Pink produced slightly more selfed than outcrossed fruit, and Souey Tung displayed high selfing. Outcrossing levels did not differ significantly between the edge and middle rows of these four cultivars. In contrast, Sah Keng and Wai Chee produced more outcrossed fruit in their edge row but more selfed fruit in their middle row. These two cultivars were at the orchard periphery, with another cultivar planted on only one side. Pollinators transported cross-pollen 56–60 m into the middle of blocks when different cultivars were planted on both sides, but this distance decreased to 42–56 m into the blocks when another cultivar was planted on only one side. Cross-pollination had few effects on fruit mass or quality, although pollination by Souey Tung sometimes increased fruit mass or Brix. These findings suggest that interplanting different cultivars of lychee can make effective use of its mixed-mating system, providing additional pollen sources in the orchard, supporting fruitlet retention, and sustaining tree productivity, without contributing greatly to quality variation in each cultivar.
ISSN:2311-7524