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Biostimulants for cotton flower and boll retention

Foliar biostimulants are applied in cotton during the peak flowering and boll-set window, typically 40-90 days after sowing, to reduce flower and young-boll shedding under heat or moisture stress. The category is regulated in India under the Plant Biostimulant Order (FCO 2021 amendment), which brought biostimulants under the Fertiliser Control Order and required registration before sale.

Composition

Four sub-categories are commonly used on cotton:

  • Amino-acid biostimulants: protein hydrolysates supplying free L-amino acids and oligopeptides; representative product Isabion (Syngenta).
  • Seaweed extracts: alkaline extracts of Ascophyllum nodosum or Kappaphycus alvarezii, supplying mannitol, alginates, betaines and trace phytohormones; IFFCO Sagarika and PI Biovita are dominant.
  • Humic-fulvic acid blends: see Humic Acid and Fulvic Acid.
  • Combination foliars that include trace micronutrients (B, Zn) for fruit set support.

Mode of action

These products do not provide nutrition in the NPK sense. Amino-acid biostimulants supply readily assimilable nitrogenous building blocks and act as chelators and stress mitigants. Seaweed extracts modulate auxin-cytokinin balance and elicit antioxidant and osmotic-stress responses, both of which reduce the abscission of young squares and bolls under stress. Humic substances improve nutrient uptake efficiency and root proliferation.

Target use and dose

Foliar application during the 40-90 DAS window, generally at 250-500 ml per acre of liquid concentrate or 1-2 g per litre of soluble powder, repeated at 10-15 day intervals through the boll-development phase. They are commonly tank-mixed with foliar boron and micronutrients to address simultaneous deficiencies during fruit set.

Safety and regulatory status

All FCO 2021 plant biostimulants must be registered with the central biostimulant committee. Approved products carry a registration number on the label and have no fixed pre-harvest interval at recommended doses.

See also: Seaweed Extract, Humic Acid, Fulvic Acid, Biostimulants Amino Acid Seaweed, Mepiquat Chloride Cotton.

References

  1. Sagarika Seaweed Biostimulant. Indian Farmers Fertiliser Cooperative.
  2. IFFCO Sagarika Seaweed Extract 28% Biostimulant. BharatAgri product profile.