Use of applicable anti-ethylene compound prior harvest is highly demanded especially with climacteric fruits such as apples. Effects of preharvest sprayable 1-methylcyclopropene (1-MCP), ethephon and ProTone (contains abscisic acid) alone... more
Use of applicable anti-ethylene compound prior harvest is highly demanded especially with climacteric fruits such as apples. Effects of preharvest sprayable 1-methylcyclopropene (1-MCP), ethephon and ProTone (contains abscisic acid) alone or in combination on preharvest abscission, fruit quality and storability were studied on "Anna" apples (Malus domestica Borkh.). During 2013 and 2014 seasons, "Anna" apple trees were sprayed at the mature green stage with 1-MCP at 1 mM (54.3 ppm) or 2 mM (108.6 ppm), then one week later, they were followed by either ethephon at 50 ppm or ProTone at 50 ppm, as well as sole application of ethephon at 50 ppm and ProTone at 50 ppm. Random samples were collected from each tree after one week of ethephon or ProTone containing treatments, and then divided to two groups, the first to monitor the changes in preharvest abscission, physical and chemical characteristics at harvest. Meanwhile, the second group fruits stored for 30 days at 2 oC in air (85-95% relative humidity). In contrast to either ethephon or ProTone as individual application, 1-MCP treatments caused a significant reduction in preharvest abscission percentage of "Anna" apples while maintaining fruit firmness. Moreover, ethephon or ProTone resulted in a significant reduction of flesh firmness at the red (exposed) or green cheek. Such reduction was mitigated when 1-MCP preceded the application of both compounds. Meanwhile, a drastic increase in anthocyanin occurred at the red cheek with ethephon treatment alone or when followed the 1-MCP treatment by one week. ProTone, however, did not cause a significant alteration in anthocyanin at the green cheek. On the other hand, assessment of fruits after one month of cold storage proved that the application 1-MCP mitigated the adverse influence of either ethephon or ProTone on flesh firmness. Moreover, ethephon-treated fruits had greater content of anthocyanin on both fruit cheeks while ProTone caused a significant increase in anthocyanin at the red cheek only as compared with the control. It could be recommended to apply sprayable 1-MCP at 1 mM to mature green "Anna" apples to reduce preharvest abscission and mitigate the adverse effect of ethephon or ProTone that followed such anti-ethylene compound while improving quality and reducing the loss of flesh firmness at harvest or after cold storage.
