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Outline
Aiming to address the needs of modern agriculture in monitoring the overall crop growth status and developmental trends across various growth stages, and enable rapid, non-destructive crop assessment, a handheld crop normalized difference vegetation index (NDVI) sensor based on an active light source was developed. The sensor integrated narrow-band LEDs at 650 and 850 nm, along with Si PIN photodetectors, ensuring stable light output and precise signal acquisition. NDVI values were measured by using signal modulation and demodulation techniques across 60 wheat canopies subjected to four different fertilization levels. Experimental results demonstrated excellent light source stability, with standard deviations at both wavelengths maintained within 0.9 mV. In optical calibration experiments conducted at varying measurement heights, the results exhibited a strong linear relationship to the calibration parameters, with correlation coefficients (R2) exceeding 0.97. When the measurement height ranged from 20 cm to 40 cm, NDVI outputs remained largely stable, with root mean square errors (RMSE) of 0.025 and 0.015, respectively. Moreover, the sensor effectively mitigated the influence of ambient light fluctuations, ensuring consistent measurement results. A comparative analysis with a reference instrument demonstrated strong agreement in NDVI measurements, with R2 of 0.79 and RMSE of just 0.031. These results confirmed that the developed handheld crop growth sensor delivered high reliability and accuracy in practical applications, providing robust technical support for crop growth monitoring and a sound scientific foundation for modern agricultural production management.
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| 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 |
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