Postharvest quality of sweet cherry fruits as affected by bioregulators

During the cold storage of sweet cherry, severe losses can occur due to the water loss, phytopathogenic fungi and physiological disorders. The aim of this research was to assess the effects of treatments with NAA (α-naphthaleneacetic acid), BA (6-benzyladenine), and GA3 (gibberellic acid) on fruit quality at harvest and after 21 days of storage under two regimes, including 0°C, RH (relative humidity) 90% and 3°C, RH 70%, and after additional shelf life exposure. Sweet cherry cultivars – ‘Summit’, ‘Kordia’ and ‘Regina’ – were treated with bioregulators at the end of flowering. NAA significantly increased the fruit weight at harvest compared to the control in all cultivars assessed. BA stimulated the fruit growth in ‘Kordia’ and ‘Regina’, while it was ineffective in ‘Summit’. GA3 caused significant increase in fruit weight by 8.3% in ‘Kordia’ only. Moreover, BA and GA3 induced a higher firmness of fruits at harvest. Weight loss of fruits during storage at 0°C, RH 90%, was increased with NAA and reduced with GA3 in ‘Regina’ only. BA and GA3 reduced the weight loss of sweet cherry fruits stored at 3°C, RH 70%. Bioregulator treatments increased TA (titratable acidity) in fruits at harvest, while the effects on TA during storage were variable depending on the cultivar. ‘Summit’ had the highest sensitivity to storage fruit rot. BA and GA3 decreased the disease occurrence on fruits stored at 0°C in ‘Summit’ and ‘Kordia’.