Using a Portable Active Sensor to Monitor Growth Parameters and Predict Grain Yield of Winter Wheat

Abstract

Rapid and effective acquisition of crop growth information is a crucial step of precision agriculture for making in-season management decisions. Active canopy sensor GreenSeeker (Trimble Navigation Limited, Sunnyvale, CA, USA) is a portable device commonly used for non-destructively obtaining crop growth information. This study intended to expand the applicability of GreenSeeker in monitoring growth status and predicting grain yield of winter wheat (Triticum aestivum L.). Four field experiments with multiple wheat cultivars and N treatments were conducted during 2013–2015 for obtaining canopy normalized difference vegetation index (NDVI) and ratio vegetation index (RVI) synchronized with four agronomic parameters: leaf area index (LAI), leaf dry matter (LDM), leaf nitrogen concentration (LNC), and leaf nitrogen accumulation (LNA). Duration models based on NDVI and RVI were developed to monitor these parameters, which indicated that NDVI and RVI explained 80%, 68–70%, 10–12%, and 67–73% of the variability in LAI, LDM, LNC and LNA, respectively. According to the validation results, the relative root mean square error (RRMSE) were all <0.24 and the relative error (RE) were all <23%. Considering the variation among different wheat cultivars, the newly normalized vegetation indices rNDVI (NDVI vs. the NDVI for the highest N rate) and rRVI (RVI vs. the RVI for the highest N rate) were calculated to predict the relative grain yield (RY, the yield vs. the yield for the highest N rate). rNDVI and rRVI explained 77–85% of the variability in RY, the RRMSEs were both <0.13 and the REs were both <6.3%. The result demonstrates the feasibility of monitoring growth parameters and predicting grain yield of winter wheat with portable GreenSeeker sensor.

Using Hand-Held Chlorophyll Meters and Canopy Reflectance Sensors for Fertilizer Nitrogen Management in Cereals in Small Farms in Developing Countries

“…Fairly accurate prediction of N uptake is essential for setting up non-invasive strategies to optimize N fertilization and to reduce the environmental risks associated with injudicious use of fertilizer N. Zhang et al [117] found that NDVI was exponentially related to leaf N accumulation at Feekes growth stages 4-7 and 8-10 of wheat and explained 68% and 75% of its variability, respectively. Cao et al [118] conducted studies in the Hebei Province of China and concluded that the three band user configurable Crop Circle ACS-470 sensor can better estimate winter wheat N status as compared to the two fixed band GreenSeeker sensor.…”

Wheat Growth Monitoring and Yield Estimation based on Multi-Rotor Unmanned Aerial Vehicle

“…Developed by the National Information Agriculture Engineering Technology Center, the portable multi-spectral growth monitoring diagnostic instrument CGMD302 can quickly measure the spectral reflectivity of a crop canopy at 720 and 810 nm; this instrument has already been applied to monitor the growth of rice, wheat, and other crops [4]. GreenSeeker, a handheld active spectrometer developed by Trimble Navigation Limited, has two fixed bands of red light and near-infrared, which can construct normalized difference vegetation index (NDVI) and ratio Vegetation Index (RVI), and be applied in the growth monitoring of rice, wheat, corn, and other crops [5,6]. These hand-held sensors have fewer wavebands, building a limited spectral index; this makes it difficult to determine fields with partial vegetation index saturation in the late growth period of crops.…”

Combining Color Indices and Textures of UAV-Based Digital Imagery for Rice LAI Estimation

“…However, unfavorable weather conditions, such as clouds or fog, may lead to the lack of applicable satellite data, consequently limiting their applications for crop monitoring that requires high temporal and spatial resolutions. For applications in small areas, many ground-based non-imaging sensors, such as GreenSeeker (Trimble Navigation Limited, Sunnyvale, CA, USA) and Crop Circle series (Holland Scientific, Lincoln, NE, USA), have also been used on canopy scale to estimate LAI, nitrogen status, and predict crop yield [12,13]. However, the overall cost of using these ground-based sensors needs to be evaluated due to the high labor input and the inefficient use of these sensors [14].…”