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Thompson Seedless grape Photo: Advcravikumar · CC BY-SA 4.0 · source ↗

Thompson Seedless grape

Thompson Seedless is the flagship table-grape cultivar of the Indian commercial grape industry and accounts for the overwhelming majority of fresh-grape exports from Maharashtra. Originally selected in California in the 19th century from the Persian "Sultanina" / "Kishmish" stock, it was introduced into India in the 1920s and now anchors the Nashik, Sangli, Solapur, Pune and Satara belts.

Key characteristics

  • Berry: oval to elongated, light-green to amber, seedless (stenospermocarpic)
  • TSS at harvest: 18-22 deg Brix
  • Bunch weight: 350-700 g; well-shouldered conical bunches under good thinning
  • Harvest window in Maharashtra: late December to March
  • Yield: 10-15 t/ac under the double-cycle export protocol; lower under untrained pandal systems
  • Mutants and selections grown commercially: Tas-A-Ganesh, Sonaka, Manik Chaman, Sharad Seedless, Sharad's Sudhakar — all derived locally through bud-sport selection

Cultivation

Thompson Seedless is grown almost exclusively on rootstocks (Dogridge or 110R, see Grapes Rootstock Dogridge 110R) to manage salinity, drought and nematode pressure on Deccan basalt soils. Vines are trained on Y-shape, flat-roof or extended Y trellises and managed with the double-cycle April back-pruning + September-October forward-pruning system (Grapes Pruning Foundation Fruit, Grapes Pruning Back Foreward). Berry size is built up with two to three gibberellic-acid (GA3) sprays for elongation and thinning (Grapes Ga3 Thinning Elongation). Drip-fertigation, deficit irrigation at veraison, and protected-cultivation poly-covers (Grapes Bagging Trellis Protected) are standard in export blocks.

Pest and disease profile

The variety is highly susceptible to downy mildew (Grapes Downy Mildew Plasmopara) on the foliage during the monsoon foundation phase and to powdery mildew (Grapes Powdery Mildew Uncinula) on bunches during the dry fruiting phase. Anthracnose (Grapes Anthracnose Elsinoe), mealybug, thrips and bunch rot also occur. Heavy spray schedules during the foundation phase make residue management (Grapes Export Residue Mrl Europe) the single biggest constraint on the export crop.

Adoption and use

Thompson Seedless and its mutants dominate the GrapeNet-registered (Grapenet Apeda Traceability) export plots that ship to Europe, the UK, the Middle East and South-East Asia between January and April. Domestically the variety is sold both as fresh table grapes and as raisins (kishmish), with most raisin processing concentrated around Sangli and Bijapur. ICAR-NRC Grapes Pune is the lead institute for variety improvement and post-harvest research.

See also: Grapes Pruning Foundation Fruit, Grapes Ga3 Thinning Elongation, Grapes Export Residue Mrl Europe, Grapenet Apeda Traceability.

Sources

  1. ICAR-NRC Grapes Pune institutional portal.
  2. Grapes Product Profile. APEDA.