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Abstract
Fruit cracking is an important disorder that can cause severe loss of marketable yield and revenue in the muskmelon (Cucumis melo) fruit industry. The physiological and environmental factors causing cracking are poorly understood. Although generally considered a physiological disorder caused by fluctuating environmental conditions, current evidence indicates that this disorder also has a genetic as well as a genotype × environment component. Certain cultivars are more susceptible than others, but wide fluctuations in irrigation, temperature, and nutrition during late fruit maturation stages appear to predispose fruit to cracking. This article summarizes the current state of our understanding of the causes of fruit splitting in muskmelons.
Fruit cracking (also known as growth cracks or fruit splitting) is a major physiological disorder that can cause significant economic losses in a wide variety of fruit including tomato (Solanum lycopersicon), cherry (Prunus avium), apple (Malus domestica), atemoya (Annona ×atemoya), peach and nectarines (Prunus persica), mango (Mangifera indica), pepper (Capsicum sp.), watermelon (Citrullus lanatus), muskmelon, citrus (Citrus sp.), and many other fruit (Matas et al., 2004; Opara, 1997; Paull, 1996; Peet, 1992; Savvas et al., 2008).
Fruit cracking is characterized by rupturing of the outer protective fruit tissues (rind), rendering the fruit nonmarketable (Matas et al., 2004). This disorder is usually associated with rapid absorption of large amounts of water, and the consequential development of abnormally higher turgor pressures than the rind can withstand, resulting in rind rupture. Even if fruit rupture does not ensue, excessive water intake can dilute solutes, reduce quality, and delay harvest maturity.
Although cracking has been documented commercially for many decades, the physiology of fruit cracking is still poorly understood. This is in part because of the difficulty in replicating the causal environmental conditions in any consistent fashion in controlled studies. This is supported by the fact that fruit cracking tends to be sporadic, being more prevalent in some years than others (Peet, 1992). However, transcriptomic events during the development of cracks between the pedicel and the fruit in melons during abscission have recently been characterized (Corbacho et al., 2013).
Certain environmental conditions such as irregular rainfall or irrigation, high temperatures, rapid fruit growth, high humidity,...