Comparison of three methods for estimating leaf area index of upland rice cultivars

Nondestructive estimation of leaf area index (LAI) using two canopy analyzers (LAI-2000 and SunScan) was compared with destructively measured LAI for four upland rice (Oryza spp.) cultivars with various types of canopy development during the period from 21 to 56 d after sowing (DAS). For the LAI-2000, LAI was estimated with or without the wide angle reading (Ring 5). When data from 50 and 56 DAS, which included LAI measured destructively of >4 m2 m–2, were omitted, the relationship of LAI measured destructively with LAI estimated by the SunScan was highly significant (R2 = 0.96) and had lower root mean square error than that with LAI estimated by the LAI-2000 without Ring 5. We conclude that by restricting the range of LAI to <4 m2 m–2, the SanScan can provide reasonable estimates of LAI.