Thermal infrared imaging of crop canopies for the remote diagnosis and quantification of plant responses to water stress in the field

Abstract

Thermal imaging using infrared (IR) is now an established technology for the study of stomatal responses and for phenotyping plants for differences in stomatal behaviour. This paper outlines the potential applications of IR sensing in drought phenotyping, with particular emphasis on a description of the problems with extrapolation of the technique from the study of single leaves in controlled environments to the study of plant canopies is field plots, with examples taken from studies on grapevine (Vitis vinifera L.) and rice (Oryza sativa L.). Particular problems include the sensitivity of leaf temperature (and potentially the temperature of reference surfaces) to both temporal and spatial variation in absorbed radiation, with leaf temperature varying by as much as 15°C between full sun and deep shade. Examples of application of the approach to phenotyping in the field and the steps in data analysis are outlined, demonstrating that clear genotypic variation may be detected despite substantial variation in soil moisture status or incident radiation by the use of appropriate normalisation techniques.

Phenotyping of Plants for Drought and Salt Tolerance Using Infra-Red Thermography

“…In sensitive genotypes, temperatures of leaf and plant body increased in water-deficit environments. In droughttolerant plants, stomata plays a key role to maintain enough moisture inside the leaf and lower temperatures under water deficit condition (Munns 2002;Jones et al 2009), as was seen in CaMsrB2 transgenic lines. Therefore RWC and stomatal conductance were found to be consistent with IR thermography under drought stress.…”

“…Relationship between physiological parameters and IR images is based on the type and nature of stress and genotypes. For instance, tolerant genotypes uptake soil water efficiently by maintaining higher stomatal conductance and therefore can show cooler leaves (Jones et al 2009;Berger et al 2010;Lu et al 2011). Further, Sirault et al (2009 proposed that leaf temperature could be an indicator of stomatal conductance.…”

“…For the selection of the salt-tolerant plants, both conventional low-throughput physiological approaches and modern high-throughput phenotyping approaches have been used. Scientists need to correlate these two approaches and to homogenize the protocol for examining adequate phenotypes under salt stress that might have some role in the regulation of plant temperature (Merlot et al 2002;Jones et al 2009;Collins et al 2010;Munns et al 2010). Stomatal regulation and plant water status are important aspects in the presence of salt stress.…”

“…Commonly, water loss from leaf needs a considerable amount of energy to convert each molecule of water from liquid to vapor. This energy is then taken away from the leaf in the evaporating water for cooling purpose (Jones et al 2009). Thus, for a given environmental or stress condition, leaf transpiration is an important determinant of leaf temperature.…”

Foreword: Plant phenomics: from gene to form and function

“…Infrared thermography as a surrogate for measurements of transpiration and photosynthetic response to stress shows great promise in high throughput plant phenomics and can be used both in controlled environments (Qiu et al 2009;Sirault et al 2009) and in the field (Jones et al 2009). The power of this approach is that it allows high throughput screening at the seedling level to be validated at the canopy level in a field environment, using the same genotypes and tools.…”