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 m 2 m −2 , were omitted, the relationship of LAI measured destructively with LAI estimated by the SunScan was highly significant ( R 2 = 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 m 2 m −2 , the SanScan can provide reasonable estimates of LAI.