Comparing Nadir and Multi-Angle View Sensor Technologies for Measuring in-Field Plant Height of Upland Cotton

Abstract

Plant height is a morphological characteristic of plant growth that is a useful indicator of plant stress resulting from water and nutrient deficit. While height is a relatively simple trait, it can be difficult to measure accurately, especially in crops with complex canopy architectures like cotton. This paper describes the deployment of four nadir view ultrasonic transducers (UTs), two light detection and ranging (LiDAR) systems, and an unmanned aerial system (UAS) with a digital color camera to characterize plant height in an upland cotton breeding trial. The comparison of the UTs with manual measurements demonstrated that the Honeywell and Pepperl+Fuchs sensors provided more precise estimates of plant height than the MaxSonar and db3 Pulsar sensors. Performance of the multi-angle view LiDAR and UAS technologies demonstrated that the UAS derived 3-D point clouds had stronger correlations (0.980) with the UTs than the proximal LiDAR sensors. As manual measurements require increased time and labor in large breeding trials and are prone to human error reducing repeatability, UT and UAS technologies are an efficient and effective means of characterizing cotton plant height.height is often positively correlated with fiber yield and water-use efficiency when cotton is grown with low soil moisture conditions [9,10]. These studies indicate that plant height is a useful phenotype for cotton breeders to identify high yielding lines, particularly under less-than-optimal environmental conditions. Unfortunately, manual measurements of plant height are labor intensive, prone to human error, and provide data for a limited number of plants. These factors lead to extreme inefficiencies for large scale breeding programs, in which thousands of such measurements must be collected.Field-based high-throughput phenotyping is a novel approach for increasing plant breeding efficiency by using proximal sensors and imagers on terrestrial or aerial platforms to generate useful phenotypic data for plant characterization. The power of high-throughput phenotyping (HTP) is the ability to characterize large populations in both time and space, which improves trait capture of dynamic plant responses to environmental conditions. Over the last 10 years, a multitude of HTP platforms and sensor packages have been developed and evaluated in various agronomic crops [11][12][13]. Platforms and sensors used for plant height evaluation include ultrasonic transducers mounted on high-clearance tractors or field carts [10,14-16], light detection and ranging (LiDAR) systems mounted on tractors and rails [13,[17][18][19][20], and compact digital color cameras mounted on either unmanned aerial systems (UAS) or terrestrial platforms [16,19,21,22].The fundamentals of ultrasonic transducer (UT) sensors are based on the time-of-flight (TOF) principle. These devices use a transmitter to send ultrasonic pulses toward an object at frequencies higher than 20 kHz while a receiver registers the pulses reflected back from the object. Distance is calculated as half of th...

Development and Validation of a Model to Combine NDVI and Plant Height for High-Throughput Phenotyping of Herbage Yield in a Perennial Ryegrass Breeding Program

“…Similar results of R 2 (0.56-0.7) from UAS-derived grassland height and RMSE of 3.50 cm from LiDAR-derived wheat height were reported. However, other reports achieved higher R 2 (0.90-0.98) applying ground-based LiDAR on wheat and cotton, aerial based-RGB (R 2 = 0.87-0.98) on barley [23,24] and ground-based sonar sensors (R 2 = 0.86) on cotton [47]. Most of these studies conducted at the plot level were of the canopy structure of plants growing as a sward plot and may be different from space-planted single plants.…”

Editorial for the Special Issue “Estimation of Crop Phenotyping Traits using Unmanned Ground Vehicle and Unmanned Aerial Vehicle Imagery”

“…For ground platform, ground fixed scanning system [15,22,30,35], handheld-based field measuring [11,14,16,32], mobile ground platform (MGP) [14,20], and lifting hoist-based elevated platform [12,36] were reported for different crops types ( Figure 2). These platforms were easy-to-use with low cost, but data acquisition was semi-automatic.…”

A data workflow to support plant breeding decisions from a terrestrial field-based high-throughput plant phenotyping system

“…Two features of this platform were critical for local FB-HTPP activities. First, the tire spacing was adjustable via a hydraulic system to accommodate plant row spacings, ranging from 1.80 to 3.07 m. Second, hydraulic lift systems were available to vertically elevate both the vehicle platform and the sensor boom to accommodate variable plant heights over time, with a total range of 1.04-2.74 m. The front boom was modified by adding a custom frame constructed from 0.04× 0.04 m extruded aluminum T-slot tubing, framing members, and hardware (Rexroth Bosch Group, Charlotte, NC, USA) for attaching proximal sensors and associated hardware as previously described by Thompson et al [25].…”

“…The model parameters depended on the experimental design and project objectives. Examples of models to remove outliers from field-based HTP collections can be found in Andrade-Sanchez et al [3], Pauli et al [15], and Thompson et al [14,25]. Outliers are removed from the data in an iterative fashion ( Fig.…”