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Application of gibberellic acid to sweet cherries (Prunus avium L.)
cv. 'Sweetheart': effects on fruit quality at harvest and during
cold storage.
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S. Horvitz1, C. Godoy2, A.F. López
Camelo1 and A. Yommi1
1Laboratorio de Postcosecha y Calidad de Frutas y Hortalizas, INTA, EEA Balcarce. CC 276. 7620. Balcarce, Argentina.
- E-mail: shorvitz@balcarce.inta.gov.ar
2Cátedra de Fruticultura, Facultad de Ciencias Agrarias (UNMdP). CC
276. 7620. Balcarce, Argentina.
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INTRODUCTION
A preharvest gibberellic acid (GA) spray can be used to improve sweet cherry quality, increasing fruit size and firmness at harvest. The objective of this study was to evaluate the effects of a GA treatment on fruit quality at harvest and during cold storage.
MATERIALS AND METHODS
Sweet cherry trees cv. 'Sweetheart' were sprayed with GA when fruit color was straw-yellow (95 days after full bloom). Treatments consisted of 10 and 30 ppm GA and an untreated control, using a completely randomized experimental design with five replications. Harvest was done when fruits reached their commercial color. Quality was evaluated on each treatment harvest day and during cold storage in terms of: weight, size, color, firmness, flesh/stone ratio, pedicel aspect, soluble solids content (SSC), cracking index and fresh weight loss. For cold storage analysis, fruit samples were packed in LDPE bags and maintained at 0°C during 21 days.
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Poster completo. Click para ampliar.
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RESULTS AND DISCUSSION
GA-treated fruits were harvested 5 days later than the control. On control harvest date, all the treatments were similar in fresh weight and SSC. However, GA-treated cherries were larger (based on equatorial diameter) and firmer than untreated fruits, while the 30 ppm GA cherries had a less intense red color
(Table 1). When the GA-treated cherries were harvested, they presented an increase in size, weight and firmness compared to the control. GA 10 ppm had the highest flesh/stone ratio, followed by GA 30 ppm and untreated fruit, while no significant differences were found for SSC and cracking
index (Table 2).
During cold storage, firmness increased towards the end of the experiment in all the treatments. However, GA 30 ppm was firmer than GA 10 ppm and this, in turn, firmer than the control
(Figure 1). No differences were found in color and SSC and regardless of the quantity of GA applied, the percentage of cherries with commercial pedicels was higher for treated fruits
(Figure 2).
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Table 1: Fruit characteristics at control-fruit harvest date.
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Control
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10 ppm GA
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30 ppm GA
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Ecuatorial diameter (mm)
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24.10 bz
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25.22 a
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25.20 a
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Firmness
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85.80 c
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91.40 b
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94.40 a
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Hue angle
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20.04 b
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22.31 ab
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24.06 a
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zValues followed by the
same letter are not significantly different (P>0.05)
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Figure 1. Click para ampliar.
Figure 2. Click para ampliar.
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Table 2: Fruit quality characteristics evaluated at harvest of each treatment.
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Control
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10 ppm GA
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30 ppm GA
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Color (hue angle) |
20.04 az |
20.86 a |
20.94 a |
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Fresh weight (g) |
6.92 b |
7.96 a |
7.80 a |
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Equatorial diameter (mm) |
24.10 b |
25.89 a |
25.90 a |
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Firmness |
85.80 b |
89.20 a |
90.80 a |
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Flesh/pit ratio |
12.80 c |
15.81 a |
14.53 b |
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SSC(ºBrix) |
20.54 a |
19.62 a |
19.84 a |
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Cracking index |
45.92 a |
35.28 a |
35.28 a |
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zValues followed by the same
letter are not significantly different (P>0.05). |
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CONCLUSIONS
The preharvest application of GA delayed sweet cherries ripening, extending the fruit growing period and yielding larger and firmer fruits. The higher quality obtained with both rates of GA was also maintained during the 21 days of cold storage. Furthermore, during this period, the percentage of fruits with commercial pedicels was always higher for treated cherries than for the control.
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