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Subject: Horticulture × End date: 2018 × Start date: 2018 × Type: Thesis × Thesis Type: Ph.D ×
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    ThesisItemOpen Access
    Studies on quality improvement and storage life in flame seedless grapes (Vitis vinifera L.) through use of pre and postharvest application of chemicals
    (Punjab Agricultural University, Ludhiana, 2018) Simranbir Kaur; Arora, N.K.
    The present research entitled “Studies on quality improvement and storage life in Flame Seedless grapes (Vitis vinifera L.) through use of pre and post-harvest application of chemicals” was conducted at Fruit Research Farm and Postharvest Laboratories, Department of Fruit Sciences, Punjab Agricultural University, Ludhiana during two consecutive seasons 2017 and 2018. The investigation was conducted in three experiments viz. cumulative effect of forchlorfenuron (CPPU), berry thinning and ethephon on time of ripening, yield and quality of ‘Flame Seedless’ grapes; preharvest applications of hexanal formulation and methyl jasmonate on fruit quality and storage life of ‘Flame Seedless’ grapes and effect of postharvest applications of hexanal, calcium chloride & salicylic acid on fruit quality and storage life of ‘Flame Seedless’ grapes. In quality improvement studies, the grape vines were treated with CPPU (1, 2 & 3 ppm) and berry thinning at pea stage in combination with foliar application of ethephon (300, 400 & 500 ppm) at veraison stage. Results revealed that maturity time was delayed by 5-7 days in grape vines perceived highest concentration of CPPU (3 ppm) in comparison with berry thinning + ethephon (400 ppm) treatment. Foliar spray of CPPU @ 1 ppm + ethephon @ 400 ppm significantly improved the average yield (26.81 Kg/ vine) and quality of grape clusters viz. cluster weight (338.04 g), cluster length (22.82 cm), berry size (1.70 × 1.69 cm) and berry weight (2.58 g), berry pedicel diameter (1.44 mm), berry firmness (224.42 g force-1), TSS: acid ratio (34.79), sugars (14.39 %), juice pH (3.49), anthocyanin accumulation (34.29 mg/l) and CIRG index (3.47). However, an adverse effect on fruit quality parameters has been observed in response to higher concentration of CPPU (3 ppm) where ethephon remained partially effective to overcome the detrimental effects; although positive influence on berry firmness and yield characters was documented. No significant effect on phenolic concentration improvement was observed with respect to CPPU treatments as compared to berry thinning treatments. Potential of preharvest applications of hexanal formulation, methyl jasmonate and ethephon was investigated for evaluation of pre and postharvest quality of grapes. Two superimposed application of hexanal formulation (1.0, 1.5 and 2.0 %) were given before 15 and 30-days of harvesting, whereas methyl jasmonate (100, 200 and 300 ppm) and ethephon (400 ppm) was sprayed at veraison stage. Clusters were harvested at commercial mature stage for the evaluation of initial and postharvest quality attributes after 15, 30, 45 and 60 days of storage. Grape clusters were harvested and packed in low density polythene bags followed by storage at 0-2oC and 90-95 % RH. Results revealed that the earliest ripening (June 6) was induced by ethephon @ 400 ppm treatment. The maximum average yield (26.46 kg/vine) was obtained from grape vines treated with foliar application of hexanal formulation @ 2.0 percent through increasing the average cluster weight (340.62 g), cluster length (24.06 cm), berry weight (2.48 g), berry size (1.56 × 1.61 cm) and berry pedicel diameter (1.38 mm). Hexanal formulation @ 2.0 % significantly improved the berry firmness (217.60 g Force-1), specific gravity (1.11 g cm-1) as well as total phenolic content (43.71 mg GAE/100 g FW). Grape clusters treated with ethephon @ 400 ppm accumulated highest mean TSS (18.4 %), TSS: acid ratio (43.59), total sugars (16.11 %), juice pH (3.89), anthocyanin content (47.27 mg/l) and lowest mean titratable acidity (0.42 %). Pre-harvest foliar application of hexanal formulation @ 2.0 % was found to be the most effective in maintaining the postharvest life of ‘Flame Seedless’ grapes under 60 days of cold storage by reducing the physiological loss in weight (2.06 %), berry shattering (1.16 %), PME activity (0.13 µg/g FW) while maintaining the higher mean palatability rating (7.92), rachis freshness (0.86), TSS (17.8 %), TA (0.54 %), total sugars (16.39 %) and anthocyanin content (49.24 mg/l) during entire storage period as compared to other treatments, where ethephon (400 ppm) treatment exerted prejudicial effects during cold storage studies. The effect of postharvest applications of hexanal, calcium chloride and salicylic acid was evaluated for quality maintenance of table grapes cv. ‘Flame Seedless’ under extended cold storage. Uniform coloured grape clusters were harvested at commercial maturity and treated for five 5-miutes in aqueous solution of hexanal (0.010, 0.015 and 0.020 %), calcium chloride (0.5, 1.0 and 1.5 %) and salicylic acid (1, 2 and 3 mM). Treated fruits were packed in low density polythene bags aligned with grape guard and stored at 0-2oC and 90-95 % RH followed by quality evaluation upto 60 days. Grape clusters treated with hexanal @ 0.015 and 0.020 % and calcium chloride @ 1.5 % were moderately to very much desirable after 60 days cold storage. Hexanal @ 0.015 % was found to be the most efficacious treatment in maintaining the postharvest life of ‘Flame Seedless’ grapes upto 60 days cold storage by reducing the physiological loss in weight (1.70 %), berry shattering (1.53 %), titratable acidity (0.54 %), PME activity (0.12 µg/g FW and maintaining the palatability rating (8.21), rachis freshness score (0.18), TSS (17.9 %), total sugars (16.51 %), anthocyanin content (57.26 mg/l) at higher level during entire storage period as compared to other treatments.