Content area
Full text
Received Oct 21, 2017; Revised Feb 18, 2018; Accepted Mar 7, 2018
This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
1. Introduction
Phenotyping morphological and physiological traits of plants is one of the most laborious tasks in plant breeding and thus automated high-throughput plant phenotyping (HTP) facilitates measurement of such traits. Visible light (RGB) imaging facilitates measurement of plant’s morphological traits such as biomass, height, width, color, number of leaves, and roots to estimate plant growth rate, health, nutrition status, drought stress, water-use efficiency, nutrient-use efficiency, and early vigour [1–4]. 3D imaging can additionally measure traits such as leaf angle and leaf area which affect photosynthesis efficiency of the plants [5–7]. Hyperspectral, thermal, near-infrared (NIR), and fluorescent imaging are useful for detecting abiotic and biotic stresses [8–12]. While RGB imaging is a common feature in most facilities, some also offer fluorescence, thermal, NIR, or UV imaging. 3D imaging is popular and is available at bigger facilities such as Agrobios Plant Scanalyzer (APS) facility in Italy and The Plant Accelerator-Australian Plant Phenomics Facility. Several freely available software programs are available for image analysis [13] such as HTPheno [14], PlantCV [3], Easy Leaf Area [15], Integrated Analysis Platform [16], ImageHarvest [17], and Canopeo [18].
Whole plant biomass and growth rate at the seedling stage are traits that correlate well with early vigour and can be estimated by HTP in cereal crops. Higher early vigour is associated with higher water-use efficiency [19], nitrogen and phosphate uptake [20, 21], and weed competition [22]. 3D imaging with a NIR camera was used to measure early vigour traits such as leaf length and width and tillering in wheat [5]. Thus, HTP can aid in the evaluation of plants for early vigour based on plant biomass and growth rate both in the controlled conditions [17, 20, 23–26] and in the field [4, 26–28].
Major limiting factors for HTP in the controlled conditions are access to an imaging facility or the costs for establishing one. Thus, such facilities are established with the aim of providing phenotyping as a service and when a high-throughput and continuous use of the facility is anticipated....