Paddy booting/panicle-initiation fertilizer dose

The final scheduled fertiliser top-dress in paddy is timed to panicle initiation - roughly 45-60 days after transplanting - and is intended to drive panicle differentiation, grain set and grain filling rather than vegetative tillering.

Principle

By panicle initiation the crop's nitrogen demand shifts from tiller production to spikelet differentiation and grain weight. Potassium uptake also peaks at panicle initiation through grain filling, and the K2O split rule from IRRI - 50% basal plus 50% at panicle initiation when total K2O exceeds 30 kg/ha - is designed to match supply to this demand.

Implementation

The standard top-dress combines urea with muriate of potash (MOP, KCl) applied to a moist field. TNAU and ICAR guidelines recommend blending urea with moist soil before broadcasting to improve nitrogen-use efficiency. Foliar mono-potassium phosphate (0:52:34, MKP) is widely used at booting to supply both phosphorus and potassium when soil application is constrained. Sulphur and micronutrients - notably zinc (Micronutrient Deficiency Paddy) - added to the final dose improve filled-grain percentage and grain protein.

Adoption context

This stage-specific dose is part of the broader panicle-stage management window (Paddy Panicle Stage Management) and follows the tillering-stage spray window (Paddy Tillering Spray 25 50 Dat). It applies to transplanted (Transplanting Paddy) and direct-seeded systems alike, with timing adjusted for the shorter calendar of DSR.

Limitations

Late nitrogen application after panicle initiation increases canopy humidity at heading and exacerbates BLB, sheath blight, neck blast and false smut. Overdosing urea late also promotes sucking-pest flares such as brown planthopper. Foliar nutrition is a supplement to, not a substitute for, properly timed soil application.

References

Nutrient Management Paddy. TNAU Agritech Portal.
Potassium (K). IRRI Rice Knowledge Bank.