Harvest Index

Harvest index measures how efficiently a crop converts its total above-ground growth into the part that farmers actually harvest as yield. It works as a ratio because both grain yield and total biomass are measured in the same mass units, so dividing harvested economic output by total plant mass gives a dimensionless fraction. A higher harvest index means a larger share of the plant’s resources ended up in grain rather than stems, leaves, and other vegetative tissue.

Use this in crop physiology, breeding, and agronomy when comparing cultivars, management practices, or environments in terms of yield partitioning. It is especially useful when you want to know whether a low grain yield is due to poor biomass production or poor allocation of biomass to grain.

• Using total grain plus straw instead of total biomass in the denominator
• Mixing units, such as grain in kg/ha and biomass in t/ha, without converting first
• Interpreting harvest index as a percentage without multiplying the decimal by 100