Niraj Kumar, N. K. Arora,M.I.S Gill, J.S Brarand Gagandeep Kaur

Niraj Kumar, N. K. Arora,M.I.S Gill, J.S Brarand Gagandeep Kaur

Effect of pre-harvest sprays of ascorbic acid and calcium chloride on fruit
quality of grapes (Vitis vinifera L.) cv. Flame Seedless

NIRAJ KUMAR, N. K. ARORA,M.I.S GILL, J.S BRARAND GAGANDEEP KAUR

Department of Fruit Science

Punjab Agricultural University, Ludhiana, Punjab, India 141004

ABSTRACT

An experiment was conducted to improve fruit quality of Flame Seedless grapes with pre-harvest treatments of calcium chloride and ascorbic acid. The pre-harvest sprays of ascorbic acid and calcium chloride were given at fruit-set and veraison stage in treatment T1 to T6. The treatment T7 (Bunch thinning + GA3 40ppm) and T8 (75% crop load + Ethephon at verasion @ 400ppm) was also included for comparison. The fruit were harvested at fully ripe stage. The time of ripening was advanced by 5-days in the treatment T8 (crop load 75% + ethephon 400 ppm) as compared to control, while in the treatment T7, in which bunch thinning + gibberellic acid 40 ppm was applied time of ripening was advance by 3-days.The treatment T7 i.e. bunch thinning + gibberellic acid resulted in significantly higher yield (33.54 kg/vine) followed by treatment T8 (75 % crop load + Ethephon 400 ppm). The maximum bunch weight (345.57g), bunch length (23.42 cm) and bunch breadth (14.52 cm) were found in treatment T7 (Bunch thinning + gibberellic acid 40 ppm). Fruit quality with respect to higher total soluble solids (TSS), lower acidity, higher sugars and anthocyanin content was also recorded in treatment T8 (75 % crop load + Ethephon 400 ppm).

Key words: Ascorbic acid, Calcium chloride, Ethephon, Flame Seedless, Gibberellic acid

Although, the grapes are commercially grown in the tropical regions of India, but it early ripening variety can be successfully grown in the regions of northern India too. The grapes grown in this region have higher productivity than grapes grown in commercial region of India. ‘Perlette” is to leading cultivar of this region which occupies 90 percent area under grapes. To restrict the monoculture of this cultivar recently, coloured Flame Seedless grapes, has been recommended in northern India for commercial cultivation for table purpose (Anonymous 2009). Flame Seedless’ is a complex hybrid, whose parents include Sultanina, Cardinal, Malaga and Muscat d’ Alexandric, and was developed in early 1960s by John Weinberger in California (Vander Merwe et al. 1991). Previously, various attempts have been made to improve fruit quality of Flame Seedless grapes with use of pre-harvest sprays of chemicals like GA3, ethephon and calcium chloride (Ramteke et al. 2002, Fatma and Aisha 2005). However limited information is available regarding effect of pre-harvest application of chemicals like ascorbic acid and calcium chloride on fruit quality of Flame Seedless grapes under subtropical conditions of India. Therefore, the present study was conducted to ascertain the effect of ascorbic acid and calcium chloride on fruit quality of Flame Seedless grapes.

MATERIAL AND METHODS

Experimental details:The experiments comprised of nine treatments with three replications in each treatments.Total numbers of vines were 27. Spray of chemical was done at two stages i.e.pea stage and colour break stage. The various treatments consist of T1 (Ascorbic acid 750 ppm), T2 (Ascorbic acid 1000 ppm), T3 (Ascorbic acid 1250 ppm), T4 (Calcium chloride 0.25%), T5 (Calcium chloride 0.5%), T6 (Calcium chloride 1%), T7 (Bunch thinning + Gibberellic acid 40 ppm), T8 (Crop load 75 % + ethephon 400 ppm) and T9 (control). After harvesting fruits were brought to laboratory at department of Fruit science, P.A.U Ludhiana for analysis of various physico-chemical properties.

Physical properties:At the time of harvest (2nd week of July) bunches were picked and counted.Bunch weight was calculated by weighing of ten randomly selected bunches from each vine and multiplied with counted bunches to record yield. Ten bunches per vine were selected at random and their length (cm) was recorded and mean length of the bunch was worked out. The pedicel diameter (mm) of 10 randomly selected berries was taken with digital caliper and average pedicel diameter for each treatment was calculated. The weight (g) of 50 randomly selected berries was taken with weighing balance and average berry weight for each treatment was calculated. The berry size (cm) of 10 randomly selected berries was taken with digital caliper and average berry size for each treatment was calculated. Fruit texture was determined by using texture analyser instrument by penetrating cylinder 2mm/second. The results were expressed as a resistance force of the skin or flesh (gf)

Chemical properties:The soluble solids (TSS) content of the fruit was measured with hand refractometer and correction at 20o C was applied and the results were expressed in percent (AOAC 2000). The acidity (%) of the fruit was estimated by titrating the known volume of juice against N/10 sodium hydroxide. TSS: acid ratio was calculated by dividing the values of TSS with the corresponding values of titratable acidity. Total sugars were estimated by following the AOAC (2000) method. For anthocyanin estimation5 g of sample were taken and macerated using motar and pestle with small amount of ethanolic HCL (made by 85 parts 95 % ethanol and 15 parts of 1.5 N HCL). It was taken into 100 ml beaker and volume up to the mark with ethanolic HCL and kept overnight at 4oC. Following morning the mixture was filtered through Whatman’s No.1 filter paper and residue on the filter paper was washed repeatedly with ethanolic HCL and volume was made up to 100 ml with the same solvent. It was again filtered through fine millipore and 10 ml of aliquat was taken and diluted up to 20 ml with ethanolic HCL. Then the flask was kept in dark for 2 h after that absorbance was measured at 535 nm wavelength by spectrophotometer. The obtained data were statistically analyzed by Randomized Block Design (RBD) described by Singh et al. (1998).

RESULTS AND DISCUSSION

Data on the effect of various pre-harvest treatments on time of ripening (Table 1) indicated that in the treatment T8 (75% crop load + ethephon 400 ppm) time of ripening was advanced by 5-days as compared to control. While, in the treatment T7, in which bunch thinning + gibberellic acid 40 ppm time of ripening was advanced by 3 days. In present study, the advancement of maturity was due to the fact that ethylene is a ripening harmone so it accelerated berry ripening.Likewise, Rao et al. (1974) reported that proper concentration of ethephon with standard timing of its application was very effective for early maturity of Beauty Seedless grapes.

Singla et al. (1992) reported that ethephon 750 ppm advanced ripening by 7-days in ‘Early Muscat’ and by 8-days in cv. Gold. The pre-harvest sprays of ascorbic acid and calcium chloride significantly affected the fruit yield in Flame Seedless grapes. The treatments in which calcium chloride was sprayed @ 0.25 and 0.5 percent recorded 28.68 kg and 25.42 kg fruit yield per vine, respectively which was significantly lower than control (28.29 kg/vine). The treatment T7 i.e. bunch thinning + gibberellic acid 40 ppm resulted in significantly higher yield (33.54 kg/vine) followed by treatment T8 (75 % crop load + Ethephon 400 ppm) in which recorded 31.05 kg fruit yield per vine was recorded. Gowda et al. (2006) found that application of 20, 25, 30 and 45 mg/l GA3 at 40, 50, 55, and 65 days after October pruning was found optimal in order to attain higher yield (5.53 kg/vine) and good quality of Thompson Seedless grapes under Banglore conditions.

Table 1: Effect of pre-harvest treatments on time of ripening, yield, bunch weight and bunch size of Flame Seedless grapes

Treatments / Time of ripening / Yield (kg/vine) / Bunch weight (g) / Bunch length (cm) / Bunch breadth (cm)
T1-Ascorbic acid 750 ppm / 5/6 / 29.74 / 248.62 / 22.08 / 11.95
T2 -Ascorbic acid 1000 ppm / 7/6 / 28.56 / 235.64 / 21.41 / 11.89
T3- Ascorbic acid 1250 ppm / 8/6 / 26.42 / 223.87 / 20.51 / 11.75
T4- Calcium chloride (0.25%) / 3/6 / 28.68 / 263.16 / 22.37 / 12.97
T5- Calcium chloride (0.5%) / 6/6 / 25.42 / 260.42 / 22.21 / 12.77
T6-Calcium chloride (1.0 %) / 9/6 / 24.50 / 254.41 / 22.14 / 12.49
T7-Bunch thinning + GA3 (40ppm) / 4/6 / 33.54 / 345.57 / 23.42 / 14.52
T8 - 75 % crop load + Ethephon (400 ppm) / 2/6 / 31.05 / 282.57 / 20.16 / 12.07
T9- control / 7/6 / 28.29 / 220.52 / 19.62 / 10.98
CD (p=0.05) / -- / 2.66 / 2.10 / 1.95 / 1.72

(Data are the mean of three replications)

The treatment in which bunch thinning + GA3 40 ppm was used, recorded significantly higher bunch weight (345.57 g) as compared to other treatments.The treatment T8 i.e. 75% crop load + ethephon 400 ppm recorded bunch weight 282.57 g, which was significantly higher than bunch weight obtained with application of calcium chloride and ascorbic acid. The minimum bunch weight (220.52g) was registered in untreated control. The increase in bunch weight, as observed in present study might be attributed to availability of more food materials due to decrease in crop load by bunch thinning and increase of cell division with GA3 application. GA3 has been used for seedless grape production to increase berry and bunch weight, and cause thinning of clusters (Luet al.1995, Omran and Girgis 2005). Abu-Zahira and Salameh (2012) also found that application of GA3 or GA3+ girdle resulted in heavier berries as well as increased in bunch weight.

The data regarding bunch length revealed that all the treatments increased the bunch length over control (Table 1). The maximum bunch length (23.42 cm) was recorded in treatment T7 (bunch thinning + GA3 40 ppm) followed by 22.37 cm and 22.21 cm bunch length in treatment T4 (calcium chloride 0.25%) and T5 (calcium chloride 0.5%), respectively. The treatments in which ascorbic acid was sprayed, bunch length ranged from 20.51 to 22.0 cm. The control registered the lower bunch length (19.62 cm).Previously, Lakshmananet al. (1992) found that spraying of gibberellic acid @ 50 ppm at pea-stage and calyptra fall stage increased bunch length in ‘Pachadraksha’ and ‘Anab-e Shahi’ grapes. According to Shehata and El- Barbary (1996) the bunch length was increased with application of gibberellic acid @ 5mg/l and fruit thinning in Flame Seedless grapes in Egypt. Pre-harvest application of gibberellic acid @ 20 mg/l increased size of cluster in Thompson and Belgrade Seedless grapes (Dimovaskaet al. 2011). The treatment T7 ( bunch thinning + GA3 40 ppm) had significantly higher bunch breadth (14.52 cm) as compared to other treatments such as 12.97 and 12.77 cm bunch breadth in treatments T4 (calcium chloride 0.25%) and T5 (calcium chloride 0.5%), respectively (Table 1). The treatments in which ascorbic acid was sprayed bunch breadth ranges from 11.75 to 11.95 cm. while, the control registered minimum bunch breadth (10.98cm).

The data (Table 2) revealed that the berry weight was recorded maximum (2.72 g) in treatment T7 (Bunch thinning + GA3 40ppm), followed by treatment T8, i.e. 75 % crop load + ethephon (400 ppm) that had 2.58 g berry weight. The treatment T4 (calcium chloride @ 0.25% had berry weight 2.34g) which was lower with berry weight (2.58 g) recorded in T8 (75% crop load + ethephon 400 ppm). Whereas, untreated control recorded minimum berry weight (1.98 g). Increase in berry weight with 75 percent crop load + ethephon 400 ppm might be due to more availability of photosynthates to the left over bunches. Harrel and Williams (1987) reported that application of GA3 to clusters increased berry weight and vine yields significantly over control. According to Zabadal and Dittmer (2000) the pre-harvest application of gibberellic acid @ 50 ppm was most effective in increasing berry weight when berries attained 5mm diameter in Vanessa Seedless grapes in USA. Roberto (2002) observed that the pre-harvest application of gibberellic acid (3g/100litre) after 30 days of flowering, increased weight of berries of ‘Rubi’ grapes in Brazil. Berry length was maximum (1.75cm) in treatment (T7) in which bunch thinning + GA3 (40 ppm) was applied followed by 1.44 cm berry length in treatment T8 (crop load 75% + ethephon @ 400 ppm) (Table2).The minimum berry length (1.33cm) was recorded in control. Gibberellic acid increased berry size of ‘Emperatriz’ seedless grape when applied after 21 days of fruit set. This effect takes place through larger berry growth rate, early uptake of glucose, sucrose and fructose and increased of absolute berry water content (Casanova et al. 2009). Kalpan (2011) studied the pre-harvest application of GA3 @ 50 mg/l had significantly increased the berry length in ‘Einset Seedless’ grapes.

Table 2:Effect of pre-harvest treatments on berry weight, berry size and pedicel length of Flame Seedless grapes.

Treatments / Berry weight (g) / Berry length (cm) / Berry width (cm) / Berry pedicel diameter (mm)
T1- Ascorbic acid (750 ppm) / 2.21 / 1.35 / 1.28 / 2.32
T2- Ascorbic acid (1000 ppm) / 2.16 / 1.27 / 1.20 / 2.27
T3- Ascorbic acid (1250 ppm) / 2.09 / 1.24 / 1.17 / 2.24
T4- Calcium chloride (0.25%) / 2.34 / 1.42 / 1.34 / 2.59
T5- Calcium chloride (0.5%) / 2.24 / 1.39 / 1.32 / 2.42
T6-Calcium chloride (1.0 %) / 2.18 / 1.38 / 1.31 / 2.38
T7- Bunch thinning + GA3 (40ppm) / 2.72 / 1.75 / 1.67 / 3.18
T8- 75 % crop load + Ethephon (400 ppm) / 2.58 / 1.44 / 1.36 / 2.35
T9- control / 1.98 / 1.33 / 1.26 / 2.19
CD (5%) / 0.32 / 0.25 / 0.20 / 0.66

The perusal of data (Table 2) revealed that the berry pedicel diameter was recorded maximum (3.18 mm) with treatment T7, i.e. bunch thinning + gibberellic acid (40 ppm) followed by 2.59 mm berry pedicel diameter in treatment T4 (calcium chloride 0.25%) and T5 (calcium chloride 0.5%). The treatments in which ascorbic acid was sprayed recorded berry pedicel diameter ranged from 2.24 to 2.32 mm. The data regards control lower berry pedicel diameter (2.19 mm) as compared to other treatments. Casanova et al. (2009) found that application of GA3 @160 mg/l increased berry peduncle length and berry pedicel diameter.

The data with respect to fruit texture of Flame Seedless grapes as affected by application of pre-harvest treatments are presented in Fig. 1. Maximum fruit firmness (182 g f) was recorded in T4 (calcium chloride 0.25%), followed by treatment T5 (calcium chloride 0.5%) which had got the fruit firmness (174.0 gf). However, the treatment T8, i.e. crop load 75%+ ethephon 400 ppm had registered lowest value of fruit firmness (142.0 gf) as compared to other treatments. Gerasopulouset al (1996) concluded that application of calcium chloride (0.375 %) increased fruit firmness in pericarp, core and skin in Kiwi fruits. Damingoetal (1999) reported that calcium chloride treatment increased lemon fruit firmness compared to control fruit.

Fig.1 Effect of pre-harvest treatments on fruit firmness of Flame Seedless grapes.

The pre-harvest sprays of ascorbic acid, calcium chloride, gibberellic acid and ethephon resulted in significant increase in total soluble solids (TSS) as compared to control (Table 3). The data total soluble solids were recorded maximum (19.46%) with treatment T8 in which 75 percent crop load was retained and 400 ppm ethephon was sprayed at verasion stage followed by treatment T7 ( bunch thinning + gibberellic acid 40 ppm) in which 18.98 percent TSS was recorded. Increase in TSS with ethephon application is in support with the findings of Sharma and Jindal (1983) who also reported an increase in TSS by ethrel application in Beauty Seedless grapes. Sudhavani et al. (2000) stated that there was a gradual increase in TSS (18.26 %) in Baneshan mango fruits when treated with GA3 (15 ppm) + carbendazim (0.05 %) as pre-harvest application. The data in Table 3 with respect to acidity contents revealed that all the treatments significantly reduced the acidity over the control. Minimum (0.68%) acidity was recorded with treatment T8 (crop load 75% + ethephon 400 ppm), followed by treatment T7 i.e. bunch thinning + gibberellic acid 40 ppm which recorded 0.71 percent value of acidity. The maximum acidity (0.92%) was recorded in control. It was evident from the data given in Table 3 that all the pre-harvest treatments significantly influenced the TSS/acid ratio. Maximum (28.61) TSS/ acid ratio was recorded with treatment T7, i.e. crop load (75%) + 400 ppm ethephon followed by the treatment T7 (bunch thinning + gibbrellic acid 40 ppm).

Table 3:Effect of pre-harvest treatments on TSS, acidity and TSS: acid ratio of Flame Seedless grapes.

Treatments / TSS (%) / Acidity (%) / TSS/acidity
T1- Ascorbic acid (750 ppm) / 16.87 / 0.81 / 20.83
T2-Ascorbic acid (1000 ppm) / 16.62 / 0.86 / 19.33
T3- Ascorbic acid (1250 ppm) / 16.48 / 0.89 / 18.52
T4- Calcium chloride (0.25%) / 17.96 / 0.70 / 25.66
T5- Calcium chloride (0.5%) / 17.67 / 0.72 / 24.54
T6 -Calcium chloride (1.0%) / 16.72 / 0.76 / 22.00
T7- Bunch thinning + GA3 (40ppm) / 18.98 / 0.71 / 26.73
T8-75 % crop load + Ethephon (400 ppm) / 19.46 / 0.68 / 28.61
T9-control / 16.32 / 0.92 / 17.74
CD (5%) / 1.40 / 0.07 / 1.82

The data presented in Fig. 2 indicated that all the treatments resulted in significant increase in anthocyanin content as compared to control. The treatment T8 in which 75% crop load + Ethephon 400 ppm was applied, recorded significantly higher (45.36 mg/100g) anthocyanin content followed by treatments T4 i.e. calcium chloride 0.25% was (38.54 mg/100g). The treatment in which ascorbic acid was sprayed recorded anthocyanin range from 31.47 to 35.72 mg/100g. The minimum anthocyanin content (27.29 mg/100g) was recorded in treatment T7 i.e. bunch thinning + gibberellic acid 40 ppm. Similarly, high anthocyanin contents were found with application of ethephon at verasion in Tannat grapes (Ferrer and Gonzalez Neves 2002). Kitamura et al. (2005) found that controlling crop load adjust the proper colouration of ‘Aki Queen’ fruits through the regulation of anthocyanin concentration in grapes.

Fig. 2: Effect of pre-harvest treatments on anthocyanin of Flame Seedless grapes.

Maximum (12.45 %) total sugar was recorded (Fig. 3A) with treatment T8, i.e. crop load (75%) + 400 ppm ethephon followed by treatment T7, i.e. bunch thinning + gibberellic acid 400 ppm (12.19 %). The treatment in which ascorbic acid and calcium chloride were sprayed, total sugar ranged from 11.25 to 12.14 percent. The control registered lower total sugar (10.92%) as compared to other treatments.

The Fig. 3B showed that the maximum (10.72) reducing sugar percentage was registered with treatment T8, i.e. crop load (75 %) + ethephon 400 ppm.

Pratap and Singh (1966) observed an increase in the content of total sugars by application of ethephon. Gaseret al (1998) reported that ethrel (500 ppm) and hand thinning increased the TSS and sugar content. Ahmad and Zargar (2005) reported that trunk girdling + ethephon with or without GA3 gave the highest juice content while ethephon gave the highest juice content, sugars content in cv. Perlette. Hydrolysis of starch to simple sugars increased the sugar content of fruits with the advancement of storage (Prashant and Masoodi 2009).

Fig. 3A3B. Effect of pre-harvest treatments on total and reducing sugar of Flame Seedless grapes.

From present study, It can be concluded that 75 percent crop loadmanagement + pre-harvest spray of ethephon @ 400 ppm at verasion stage could be an effective treatment for advancement of ripening along with improvement in fruit quality of Flame Seedless grapes.

References

Abu-Zahira T R and Salameh Moh’d N (2012) Influence of gibberellic acid and cane girdling on berry size of Black Magic grape cultivar. Middle-East Journal Scientific Research 1: 718-22.

Ahmad M F and Zargar G H (2005) Effect of trunk girdling, flower thinning, GA3 and ethephon application on quality characteristics in grape cv. Perlette under temperate Kashmir valley conditions. Indian Journal of Horticulture62: 285-87.