Application of light detection and ranging and ultrasonic sensors to high throughput phenotyping and precision horticulture: current status and challenges
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.Remote sensing: Shining light on tree productivityLIDAR should be combined with other information from groves or orchards to gain a better understanding of the factors driving tree performance and optimize it. LIDAR is a remote sensing method which 'maps' surfaces by shining light at them and measuring how long the light takes to return. Within horticulture, it's main use has been in estimating canopy volume to optimize spraying of eg. fruit trees, or fertilizer distribution. In this review, Andre Colaco at the University of Sao Paulo in Brazil and colleagues describe the evolution of this technology and its broader applications. They suggest that by combining LIDAR with other information, such as soil electrical conductivity and fertility; or historic yield, disease and pest occurrence, growers could fine tune crop production. LIDAR could also be used to evaluate the performance of new plant varieties.
Horticulture Research