Application of light detection and ranging and ultrasonic sensors to high-throughput phenotyping and precision horticulture: current status and challenges

André F Colaço,Alexandre Escolà,Joan R Rosell-Polo,José P Molin

doi:10.1038/s41438-018-0043-0

André F Colaço, Alexandre Escolà + Show 2 more

Open Access

https://doi.org/10.1038/s41438-018-0043-0

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Abstract

Ultrasonic and light detection and ranging (LiDAR) sensors have been some of the most deeply investigated sensing technologies within the scope of digital horticulture. They can accurately estimate geometrical and structural parameters of the tree canopies providing input information for high-throughput phenotyping and precision horticulture. A review was conducted in order to describe how these technologies evolved and identify the main investigated topics, applications, and key points for future investigations in horticulture science. Most research efforts have been focused on the development of data acquisition systems, data processing, and high-resolution 3D modeling to derive structural tree parameters such as canopy volume and leaf area. Reported applications of such sensors for precision horticulture were restricted to real-time variable-rate solutions where ultrasonic or LiDAR sensors were tested to adjust plant protection product or fertilizer dose rates according to the tree volume variability. More studies exploring other applications in site-specific management are encouraged; some that integrates canopy sensing data with other sources of information collected at the within-grove scale (e.g., digital elevation models, soil type maps, historical yield maps, etc.). Highly accurate 3D tree models derived from LiDAR scanning demonstrate their great potential for tree phenotyping. However, the technology has not been widely adopted by researchers to evaluate the performance of new plant varieties or the outcomes from different management practices. Commercial solutions for tree scanning of whole groves, orchards, and nurseries would promote such adoption and facilitate more applied research in plant phenotyping and precision horticulture.

Highlights

Collecting information over a grove or orchard has been greatly facilitated in the past few decades with the development of different types of sensors within the scope digital horticulture
Among different types of sensing technologies applied in digital horticulture, ranging sensors, mostly light detection and ranging (LiDAR) and ultrasonic sensors, gained attention from researchers and practitioners for their applications in fruit and nut crops
Ranging sensors are designed to measure the distance to the nearest object by emitting an electromagnetic signal in a given direction; the time between emitting and receiving the signal is used to calculate distance to the target

Summary

Introduction

Collecting information over a grove or orchard has been greatly facilitated in the past few decades with the development of different types of sensors within the scope digital horticulture. The proposed set up of the laser sensor, facing the side of the tree vertically and moving along the grove alleys to measure transversal sections of the row, was similar to the ultrasonic systems proposed by McConnell et al.[12] and by Giles et al.[13,14,15] and was later used by most of the studies in the application of LiDAR to tree crops[23,24].

Results

Conclusion