NONDESTRUCTIVE ESTIMATION OF POTATO LEAF-AREA INDEX USING A FISH-EYE RADIOMETER

Leaf area index (LAI) is widely used in many facets of potato (Solanum tuberosum L.) modelling but direct measurements have historically bee n difficult. This investigation tested the accuracy of a commercially available instrument (LI-COR LAI-2000) for measuring LAI non-destructi vely on a potato crop. Accurate estimates of LAI were difficult to obt ain with small plots of approximate to 1 m(2). Results from larger fie ld plots were extremely favourable and indicate that non-destructive m easurements of LAI in situ can routinely be estimated within 5 to 10% of the destructively measured LAI. Six thinning tests performed on fou r potato cultivars produced average root mean square error measurement s of LAI that ranged from 0.09 to 0.27.