Dynamic Physiological Phenotyping of Drought-Stressed Pepper Plants Treated With “Productivity-Enhancing” and “Survivability-Enhancing” Biostimulants

Abstract

The improvement of crop productivity under abiotic stress is one of the biggest challenges faced by the agricultural scientific community. Despite extensive research, the research-to-commercial transfer rate of abiotic stress-resistant crops remains very low. This is mainly due to the complexity of genotype × environment interactions and in particular, the ability to quantify the dynamic plant physiological response profile to a dynamic environment. Most existing phenotyping facilities collect information using robotics and automated image acquisition and analysis. However, their ability to directly measure the physiological properties of the whole plant is limited. We demonstrate a high-throughput functional phenotyping system (HFPS) that enables comparing plants’ dynamic responses to different ambient conditions in dynamic environments due to its direct and simultaneous measurement of yield-related physiological traits of plants under several treatments. The system is designed as one-to-one (1:1) plant–[sensors+controller] units, i.e., each individual plant has its own personalized sensor, controller and irrigation valves that enable (i) monitoring water-relation kinetics of each plant–environment response throughout the plant’s life cycle with high spatiotemporal resolution, (ii) a truly randomized experimental design due to multiple independent treatment scenarios for every plant, and (iii) reduction of artificial ambient perturbations due to the immobility of the plants or other objects. In addition, we propose two new resilience-quantifying-related traits that can also be phenotyped using the HFPS: transpiration recovery rate and night water reabsorption. We use the HFPS to screen the effects of two commercial biostimulants (a seaweed extract –ICL-SW, and a metabolite formula – ICL-NewFo1) on Capsicum annuum under different irrigation regimes. Biostimulants are considered an alternative approach to improving crop productivity. However, their complex mode of action necessitates cost-effective pre-field phenotyping. The combination of two types of treatment (biostimulants and drought) enabled us to evaluate the precision and resolution of the system in investigating the effect of biostimulants on drought tolerance. We analyze and discuss plant behavior at different stages, and assess the penalty and trade-off between productivity and resilience. In this test case, we suggest a protocol for the screening of biostimulants’ physiological mechanisms of action.

A High-Throughput Gravimetric Phenotyping Platform for Real-Time Physiological Screening of Plant–Environment Dynamic Responses

“…The genotype–phenotype knowledge gap reflects the complexity of genotype × environment interactions (reviewed by Dalal et al 2017; Gosa et al 2018). It might be possible to bridge this gap through the use of high-resolution, high-throughput diagnostic and phenotypic screening platforms to study whole-plant physiological performance and water-relation kinetics (Moshelion and Altman, 2015; Dalal et al 2019). The complexity of genotype × environment interactions makes phenotyping a challenge, particularly in light of how rapidly plants respond to their changing environments.…”

“…Bridging this gap is one of the greatest challenges facing modern plant science (Chen et al, 2014; Ubbens and Stavness, 2017; Danzi et al, 2019). To meet the challenges that arise in crop improvement and minimize the genotype–phenotype knowledge gap, we must balance the genotypic approach with a phenocentric one (Miflin, 2000; Dalal et al, 2019).…”

“…Recently, various high-throughput phenotyping (HTP) platforms have allowed for nondestructive phenotyping of large plant populations over time and these platforms may help us to reduce the genotype–phenotype knowledge gap (Moshelion and Altman, 2015; Singh et al, 2016; Dalal et al, 2019; Danzi et al, 2019). Most of these HTP platforms involve the assessment of phenotypic traits through electronic sensors, robotics and/or automated image acquisition (Tardieu et al, 2017; Negin and Moshelion, 2017).…”

Detection of Potassium Deficiency and Momentary Transpiration Rate Estimation at Early Growth Stages Using Proximal Hyperspectral Imaging and Extreme Gradient Boosting

“…Plant transpiration rate (TR) is an important trait that reflects the plant water influx and outflux [ 1 , 2 ]. When water is not a limiting factor, the TR depends on abiotic factors such as soil salinity and water vapor in the atmosphere, as well as photosynthetically active radiation (PAR).…”

“…Recently, a new high-throughput, whole-plant functional phenotyping system named PlantArray (PA) was developed, which can calculate the momentary and daily TR of an entire array of plants simultaneously, as well as other plant and soil attributes and interactions [ 29 ]. The PA system’s dynamic responses to changes in ambient conditions [ 3 ], nutrient stress, and biostimulants effectiveness have been recently explored [ 1 ].…”