Tropical and subtropical fruits (2+1)

Harvesting and yield

Grape is a non climacteric fruit and has to be harvested at correct stage of maturity. Degree days from full bloom gives a correct indication of maturity. Early cultivars require about 1600-2000 degree days and late cultivars about 3000 or more. A cluster having underdeveloped seedless brries known as “shot barriers” or mummies. These will be very sweet in taste.

• Treating clusters with AVG (2 Aminoethyl Vinyl Glycine) 50-300 ppm 1-3 weeks before anthesis improves berry set. Cluster thinning also helps in improving the quality. 60-70 clusters/ vine spaced 3mX3m is best.
• Girdling the shoot one week after bloom, improves berry set, after berry set improves berry size and before veraison advances ripening and uniform coloration.
• GA (40ppm) Ethrel also can be used for improving yield and quality. Ethrel (250ppm) can be used for uniform colour development (5 weeks after anthesis, 4 weeks after berry set for colour). Balancing the canopy also plays an important role in improving quality and yield.
• Grape starts yielding from 2-3 years and continues for more than 20-25 years. Average yield will be about 25-30 tonnes/ha but higher yields of 60-75 ton/ha also possible with good management.
• Grapes are packed in corrugated fibre board boxes having grape guard (craft paper coated within layer of mixture of sodium bisulphate and a plastic polymer) improve their storage life.
• Grapes can be stored grape guard or for 7-12 weeks under controlled atmosphere with 15-25% Co2 and at 0-10C.