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KMID : 0368420080510050337
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Journal of Plant Biology
2008 Volume.51 No. 5 p.337 ~ p.340
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Ethephon application induces symptoms of fruit tissue degeneration in watermelon
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Lee Sang-Gyu
Ko Kwan-Dal
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Abstract
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Vegetable Research Division, NHRI, 475 Imok-dong, Jangan-gu, Suwon, Gyeonggi-do, 440-706, Republic of Korea Flesh tissue degeneration (called blood-black heart; BBH) of watermelon (Citrullus vulgaris S.) is occasionally observed in Korea. Fruits with BBH have lower quality, a dark-red flesh, and reduced firmness of the rind, often producing an unpleasant flavor. Although causal factors are thought to be undesirable soil moisture conditions, e.g., drought or water-logging, temperature extremes, or virus infection, the mechanism for this physiological disorder is not clearly understood. It is possible that ethylene gas (C2H4) is involved in degrading the cell walls. To determine such an implication for ethylene in the occurrence of BBH, we foliar-applied various concentrations of ethephon (100, 200, 400, 800, or 1000 mg L-1) to watermelon plants at 5 or 10 d prior to harvesting, then monitored the development of this disorder in their fruits. At 400 mg L-1 or higher, quality was diminished and the fruit had softer rind tissues. About 25% of the fruits harvested at that level exhibited BBH versus 100% of the fruits exposed to 800 or 1000 mg L-1 ethephon. Concomitant with the onset of BBH, those affected fruits produced elevated amounts of ethylene gas during the 4-d measurement period. Therefore, a high incidence of BBH may well be related to this increased ethylene production, which can be triggered by both unfavorable environmental conditions and inappropriate cultural practices.
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KEYWORD
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blood-black heart (BBH) symptoms, fruit softening, rind thickness, soluble solids
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