AVG application regimes play an important role on pre-harvest drop and ripening of 'Jonagold' apples

Abstract

This study was carried out to investigate the effects of different AV G (aminoethoxyvinylglycine) treatments on pre-harvest fruit drop rates and ripening levels of 'Jonagold' apples. A total of 225 mg L-1 AVG dose was applied at once in a single application at different times or divided into doses and applied different times. Compared to control treatment, entire AVG treatments increased fruit removal force and significantly decreased the pre-harvest drop rates. AVG treatments applied at once (225 mg L-1) 8 or 4 weeks before the anticipated harvest time were found to be more effective than the divided treatments. AV G treatments inhibited ethylene biosynthesis and such an inhibition was more distinctive in single 225 mg L-1 treatments. AV G treatments decreased flesh softening, starch degradation rates and consequently retarded fruit ripening. The 225 mg L-1 AV G treatment applied 4 weeks before the harvest significantly increased L∗ value and hue angle both in the year 2010 and 2011. NAA (naphtaleneacetic acid) at 10 mg L-1 sprayed 4 and 2 weeks before anticipated harvest was found to be insignificant in control of pre-harvest fruit drops. NAA treatment decreased flesh firmness, and did not have any significant effects on ethylene biosynthesis.