Challenging the water stress index concept: Thermographic assessment of Arabidopsis transpiration.

Water stress may greatly limit plant functionality and growth. Stomatal closure and consequently reduced transpiration are considered as early and sensitive plant responses to drought and salinity stress. An important consequence of stomatal closure under water stress is the rise of leaf temperature (Tleaf ), yet Tleaf is not only fluctuating with stomatal closure. It is regulated by several plant parameters and environmental factors. Thermal imaging and different stress indices, incorporating actual leaf/crop temperature and reference temperatures, were developed in previous studies toward normalizing for effects unassociated to water stress on Tleaf , aiming at a more efficient water stress assessment. The concept of stress indices has not been extensively studied on the model plant Arabidopsis thaliana. Therefore, the aim of this study was to examine the different indices employed in previous studies in assessing rosette transpiration rate (E) in Arabidopsis plants grown under two different light environments and subjected to salinity. After salinity imposition, E was gravimetrically quantified, and thermal imaging was employed to quantify rosette (Trosette ) and artificial reference temperature (Twet, Tdry ). Trosette and several water stress indices were tested for their relation to E. Among the microclimatic growth conditions tested, RWSI1 ([Trosette - Twet ]/[Tdry - Twet ]) and RWSI2 ([Tdry - Trosette ]/[Tdry - Twet ]) were well linearly-related to E, irrespective of the light environment, while the sole use of either Twet or Tdry in different combinations with Trosette returned less accurate results. This study provides evidence that selected combinations of Trosette , Tdry , and Twet can be utilized to assess E under water stress irrespective of the light environment.

An Ethnobotanical Investigation into the Traditional Uses of Mediterranean Medicinal and Aromatic Plants: The Case of Troodos Mountains in Cyprus.

The Troodos mountains in Cyprus are a hotspot of plant diversity and cultural heritage. However, the traditional uses of medicinal and aromatic plants (MAPs), a significant aspect of local culture, have not been thoroughly studied. The aim of this research was to document and analyze the traditional uses of MAPs in Troodos. Data on MAPs and their traditional uses were collected through interviews. A database was constructed with categorized information on the uses of 160 taxa belonging to 63 families. The quantitative analysis included the calculation and comparison of six indices of ethnobotanical importance. The cultural value index was selected to reveal the most culturally significant MAPs taxa, while the informant consensus index was utilized to quantify the consensus in information obtained related to uses of MAPs. Furthermore, the 30 most popular MAPs taxa, exceptional and fading uses, and the plant parts used for different purposes are described and reported. The results reveal a deep connection between the people of Troodos and the plants of the area. Overall, the study provides the first ethnobotanical assessment for the Troodos mountains in Cyprus, contributing to a better understanding of the diverse uses of MAPs in mountain regions of the Mediterranean.

Two Inexpensive and Non-destructive Techniques to Correct for Smaller-Than-Gasket Leaf Area in Gas Exchange Measurements.

The development of technology, like the widely-used off-the-shelf portable photosynthesis systems, for the quantification of leaf gas exchange rates and chlorophyll fluorescence offered photosynthesis research a massive boost. Gas exchange parameters in such photosynthesis systems are calculated as gas exchange rates per unit leaf area. In small chambers (<10 cm2), the leaf area used by the system for these calculations is actually the internal gasket area (AG), provided that the leaf covers the entire AG. In this study, we present two inexpensive and non-destructive techniques that can be used to easily quantify the enclosed leaf area (AL) of plant species with leaves of surface area much smaller than the AG, such as that of cereal crops. The AL of the cereal crop species studied has been measured using a standard image-based approach (iAL) and estimated using a leaf width-based approach (wAL). iAL and wAL did not show any significant differences between them in maize, barley, hard and soft wheat. Similar results were obtained when the wAL was tested in comparison with iAL in different positions along the leaf in all species studied. The quantification of AL and the subsequent correction of leaf gas exchange parameters for AL provided a precise quantification of net photosynthesis and stomatal conductance especially with decreasing AL. This study provides two practical, inexpensive and non-destructive solutions to researchers dealing with photosynthesis measurements on small-leaf plant species. The image-based technique can be widely used for quantifying AL in many plant species despite their leaf shape. The leaf width-based technique can be securely used for quantifying AL in cereal crop species such as maize, wheat and barley along the leaf. Both techniques can be used for a wide range of gasket shapes and sizes with minor technique-specific adjustments.