Monitoring Leaf Water Content Based on Hyperspectra in Rice

【Objective】 The objective of the experiments is to develop a key method for fast and nondestructive monitoring leaf water content(LWC) in rice(Oryza sativa L.).【Method】 Two field experiments were conducted with different soil water conditions and rice cultivars across two growing seasons,and time-course measurements were taken on leaf hyperspectral reflectance and LWC at top four leaves over main growth stages.Several kinds of hyperspectral indices at leaf scale including ratio spectral indices(RSI),normalized difference spectral indices(NDSI) and difference spectral indices(DSI) with all combinations of two wavebands between 350 and 2 500 nm were calculated,and their relationships to LWC were analyzed.【Result】 The results indicated that the leaf spectral reflectance varied distinctly with soil water treatments and different top leaves,the sensitivity bands mostly occured within near-infrared and short-infrared spectral regions.The spectral indices as RSI(R1402,R2272) and NDSI(R1402,R2272) were linear with LWC,giving the determination coefficient of linear regression(S-R2) of 0.80,and the predicted R2(P-R2) based on the testing performance with independent datasets as 0.86.【Conclusion】 It is concluded that the RSI(R1402,R2272) and NDSI(R1402,R2272) can be used to monitor leaf water content in rice.