Li Dan, Li Fei, Hu Yun-cai, Bodo Mistele, Schmidhalter Urs
Guang Pu Xue Yu Guang Pu Fen Xi. 2016 Apr;36(4):1150-7.
Nitrogen fertilizer plays a crucial role in keeping food production in pace with population growth. However, the exceeding application of nitrogen fertilizer causes environmental risks. Timely and accurate quantification of canopy nitrogen content in crops is important for the rational application of nitrogen fertilizer and reduction environmental risks. The current research aimed to remotely estimate canopy nitrogen content in winter wheat and summer maize. Experiments with different N rates for different cultivars of wheat and maize were conducted in southeast Germany and in the North China Plain from 2008 to 2011. The results showed that, compared with traditional red light based spectral parameters, optimized spectral parameters significantly improved the prediction capacity, overcoming saturation problem in deriving canopy nitrogen content of wheat and maize. Band combination of optimized parameters varied with the difference in species and canopy structure of crops. The optimized bands concentrated on 730760 and 760800 nm. The best performing spectral parameter was Rλ766/Rλ738-1 for maize, Rλ796/Rλ760-1 for wheat and Rλ876/Rλ730-1 for wheat and maize combination. The validation results further confirmed that the optimized spectral parameters had the lowest predictive error, indicating that optimized spectral indices could estimate canopy nitrogen content of crops. In conclusion, the band optimization of spectral parameters is a promising approach to derive canopy N content in wheat and maize. The findings from this study may be useful for designing improved nitrogen diagnosis systems and for enhancing the applications of satellite-based sensors.
氮肥在使粮食产量跟上人口增长步伐方面发挥着关键作用。然而，过量施用氮肥会带来环境风险。及时、准确地定量作物冠层氮含量对于合理施用氮肥和降低环境风险至关重要。当前的研究旨在对冬小麦和夏玉米的冠层氮含量进行遥感估算。2008年至2011年期间，在德国东南部和中国华北平原针对小麦和玉米的不同品种进行了不同施氮量的试验。结果表明，与基于传统红光的光谱参数相比，优化后的光谱参数显著提高了预测能力，克服了在推导小麦和玉米冠层氮含量时出现的饱和问题。优化参数的波段组合因作物种类和冠层结构的差异而有所不同。优化后的波段集中在730760纳米和760800纳米。对玉米表现最佳的光谱参数是Rλ766/Rλ738 - 1，对小麦是Rλ796/Rλ760 - 1，对小麦和玉米组合是Rλ876/Rλ730 - 1。验证结果进一步证实，优化后的光谱参数具有最低的预测误差，表明优化后的光谱指数能够估算作物冠层氮含量。总之，光谱参数的波段优化是一种推导小麦和玉米冠层氮含量的有前景的方法。本研究的结果可能有助于设计改进的氮素诊断系统，并增强基于卫星的传感器应用。
