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SPAD variability of summer maize with different controlled- release fertilizers based on UAV remote sensing |
MA Hongyu1,LI Xianyue1*,SUN Yanan1,HU Qi1,XIN Maoxin1,CHI Ligang2,ZHANG Jun2 |
1. College of Water Conservancy and Civil Engineering, Inner Mongolia Agricultural University, Hohhot, Inner Mongolia 010018, China; 2. Inner Mongolia Loop Irrigation District Water Development Center Ulanbuhe Branch, Bayannur, Inner Mongolia 015000, China |
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Abstract A multispectral remote sensing model of SPAD was constructed based on the effects of different controlled-release fertilizer dosages on SPAD, for which 15 spectral variables were selected to reveal the response characteristics of canopy SPAD distribution to nitrogen fertilizer type and controlled-release fertilizer dosage during the nodulation, tasseling and filling stages of summer maize. The results show that the controlled-release fertilizer is released slowly, and there are significant differences in SPAD of summer maize among treatments at late reproductive stage. In addition, when the controlled-release fertilizer exceeds a certain threshold(225 kg/hm2), SPAD does not increase significantly after additional controlled-release fertilizer application, which indicates that excessive nitrogen fertilizer does not sustainably increase chlorophyll content. The constructed UAV multispectral remote sensing model for SPAD of summer maize has a mean R2 of 0.61, a mean RMSE of 4.60 and a mean nRMSE of 7.60% at three fertility stages of modeling, and the maximum SPAD is finally obtained at 225 kg/hm2 of controlled-release fertilizer application of nitrogen by model estimation. Therefore, the use of UAV remote sensing technology can achieve accurate monitoring of SPAD.
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Received: 31 October 2022
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