The Comparison for Leaf Nitrogen Estimating in Rice by Chlorophyll Meters and Reflectance Spectroscopy

摘要

Handheld chlorophyll sensors is a very important technique to determine the timing and number of N applications, which can improve the fertilizer-N use efficiency and monitor leaf N status of irrigated rice. One solution-culture and two field experiments with four rice genotypes were conducted to obtain variables reflecting nitrogen (N) status at different developmental stages. The paper systemically compared SPAD indices calculated from the SPAD readings of various leaf positions and hyperspectral vegetation indices. The results showed that the indices RSI and RDSI were more reliable SPAD indices for estimating foliar N status in rice plant; In addition, from view of quickness and cheapness, chlorophyll meters are more suitable for estimating foliar N status in rice than reflectance spectroscopy on the basis of meeting accuracy requirements.