Methyl Jasmonate, a Degreening Alternative for Mandarin (Citrus Reticulata L.) Var. Arrayana Fruits

Abstract

Mandarin accounts for a significant part of the Colombian citrus fruit production, the postharvest degreening of these products to attain pigmentation being a common practice when they are harvested in the tropics. The endogenous signaling molecules such as methyl jasmonate and ethylene are produced during fruit formation, and they play a key role in postharvest and stress responses. The latter is commonly used to degreen mandarin, which, however, exhibits low sensitivity to this compound. It is therefore important to establish degreening alternatives to ethylene. Thus, the aim of this study was to determine the effect of methyl jasmonate on the degreening of Arrayana mandarin (Citrus reticulata L.). For such purpose, respiration rate, weight loss, color index, total chlorophyll, total soluble solids, firmness and total acidity were determined. The treatments applied were: methyl jasmonate (MeJA) 1 μM 24h, Ethylene (ET) 1000 ppm 20 min, 1-methylcyclopropene (1-MCP) 0.5 μL L 2h; and the combinations 1-MCP + MeJA, 1MCP + ET. Generally obtained with the MeJA and 1-MCP + MeJA treatments, the most significant results took place at 14 days after treatment implementation (DATI) for total titratable acidity, and at 4 DATI for total chlorophyll and color index. The TSS/acid ratio (maturity ratio) became constant since 7 DATI under the MeJA treatment. Thus, the use of MeJA after 1-MCP pretreatment comes to be an interesting degreening option, all the more when considering that these physiological responses have not been reported in previous studies.