Li Hongbo, E-mail: lihongbo19790127@126.com
Unmanned aerial vehicle (UAV)-based fertilization is increasingly applied in rice production; however, fertilization prescriptions are still largely dependent on empirical knowledge and lack decision support based on real-time crop nutrient status. Meanwhile, limitations in hyperspectral data processing and model construction restrict the high-precision estimation of chlorophyll content in cold-region rice, thereby constraining the accurate implementation of variable-rate fertilization. To address these issues, this study combined multiple spectral preprocessing methods with feature variable selection techniques, including uninformative variable elimination (UVE), competitive adaptive reweighted sampling (CARS), iterative retention of informative variables (IRIV), and variable iterative space shrinkage approach (VISSA), to extract key spectral bands. Models including least squares support vector regression (LSSVR), particle swarm optimization-based LSSVR (PSO-LSSVR), partial least squares regression (PLSR), and a deep learning model (1DCNN-WN) were developed for chlorophyll content inversion. Based on the inversion results, nitrogen fertilization prescription maps were generated to guide UAV-based variable-rate fertilization at the tillering stage. The results showed that the SNV-IRIV-1DCNN-WN model achieved the highest inversion accuracy under the optimal preprocessing and feature selection combinations, with an R2 of 0.687, which was 0.047, 0.031, and 0.027 higher than those of SNV-UVE-LSSVR, NL-VISSA-PSO-LSSVR, and MSC-IRIV-PLSR, respectively, while the RMSE was reduced by 0.281, 0.147, and 0.107. The coefficients of variation for no fertilization (N0), low fertilization (N1), standard fertilization (N2), and excessive fertilization (N3) treatments were 6.08%, 4.16%, 3.42%, and 3.07%, respectively, indicating good fertilization uniformity. These findings provide theoretical support and technical guidance for hyperspectral-based chlorophyll inversion and precision fertilization in cold-region rice production.
| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |