Using Infrared Thermography for High-Throughput Plant Phenotyping

Infrared thermography offers a rapid, noninvasive method for measuring plant temperature, which provides a proxy for stomatal conductance and plant water status and can therefore be used as an index for plant stress. Thermal imaging can provide an efficient method for high-throughput screening of large numbers of plants. This chapter provides guidelines for using thermal imaging equipment and illustrative methodologies, coupled with essential considerations, to access plant physiological processes.

Host plant and humidity effects on phytoseiid mite, Gynaeseius liturivorus (Acari: Phytoseiidae) egg hatchability

Gynaeseius liturivorus (Ehara) (Acari: Phytoseiidae) is a promising biological control agent for tiny arthropod pests, including Thrips tabaci Lindeman (Thysanoptera: Thripidae) known as a major pest of Welsh onion. In fields during summer, G. liturivorus is observed on soybean, but not on Welsh onion, even when numerous T. tabaci are present. To elucidate G. liturivorus's occurrence on soybean and Welsh onion in relation to relative humidity (RH), we examined its egg hatching on their seedlings under low RH conditions. Then we estimated the moisture transpiration from both plants. Egg hatching occurred only on soybean plants exhibiting greater moisture transpiration. Aiming at utilizing G. liturivorus as a biological control agent for Welsh onion production in summer, evaluation of its relative tolerance and compensation potential for drought injury is necessary. Therefore, we used five phytoseiid species including G. liturivorus and Neoseiulus californicus to estimate the RH and vapor pressure deficit (VPD) at which 50% of eggs hatch (RH₅₀ and VPD₅₀). Furthermore, we examined G. liturivorus and N. californicus egg hatching under different RH oscillation conditions. Results show G. liturivorus as the most drought-sensitive among the five species tested, but G. liturivorus is able to compensate for lethal low-RH effects on egg hatching in part by periodic exposure to high RH conditions, as observed for N. californicus.

Tansley Review No. 59 Leaf boundary layers

Studies of heat and mass exchange between leaves and their local environment are central to our understanding of plant-atmosphere interactions. The transfer across aerodynamic leaf boundary layers is generally described by non-dimensional expressions which reflect largely empirical adaptations of engineering models derived for flat plates. This paper reviews studies on leaves, and leaf models with varying degrees of abstraction, in free and forced convection. It discusses implecations of finding for leaf morphology as it affects - and is affected by - the local microclimate. Predictions of transfer from many leaves in plant communities are complicated by physical and physiological feedback mechanisms between leaves and their environment. Some common approaches, and the current challenge of integrating leaf-atmosphere interactions into models of global relevance, are also briefly addressed. Contents Summary 477 I. Introduction 478 II. Early studies 479 III. The formal description of leaf transfer 480 IV. Effects of turbulence on idealized shapes 484 V. Effects of aspect ratio and inclination 486 VI. Leaves and leaf models in forced convection 491 VII. Leaves and leaf models in mixed and free convection 493 VIII. Interpretation of leaf shape 494 IX. Leaves in plant canopies 499 X. Synopsis and conclusions 502 References 502.