Mario Pagano

Non-invasive absolute measurement of leaf water content using terahertz quantum cascade lasers

BackgroundPlant water resource management is one of the main future challenges to fight recent climatic changes. The knowledge of the plant water content could be indispensable for water saving strategies. Terahertz spectroscopic techniques are particularly promising as a non-invasive tool for measuring leaf water content, thanks to the high predominance of the water contribution to the total leaf absorption. Terahertz quantum cascade lasers (THz QCL) are one of the most successful sources of THz radiation.ResultsHere we present a new method which improves the precision of THz techniques by combining a transmission measurement performed using a THz QCL source, with simple pictures of leaves taken by an optical camera. As a proof of principle, we performed transmission measurements on six plants of Vitis vinifera L. (cv “Colorino”). We found a linear law which relates the leaf water mass to the product between the leaf optical depth in the THz and the projected area. Results are in optimal agreement with the proposed law, which reproduces the experimental data with 95% accuracy.ConclusionsThis method may overcome the issues related to intra-variety heterogeneities and retrieve the leaf water mass in a fast, simple, and non-invasive way. In the future this technique could highlight different behaviours in preserving the water status during drought stress.

Image analysis of the leaf vascular network: physiological considerations

The study of leaf vascular systems is important in order to understand the fluid dynamics of water movement in leaves. Recent studies have shown how these systems can be involved in the performance of photosynthesis, which is linked to the density of the vascular network per unit of leaf area. The aim of the present study was to highlight the correlation between a leaf vein density (VD) and net photosynthetic rate (PN), which was undertaken using a digital camera, a stereoscopic microscope, and a light source. The proposed hypothesis was tested, for the first time, on the leaves of two cultivars of Vitis vinifera (L.). A significant difference was found between the VD of mature leaves of the two cultivars. VD was also significantly correlated with the maximum leaf PN. These findings support the hypothesis that the vascular system of grape leaves can be correlated with leaf photosynthesis performance.

Propagative material of grapevine: RFID technology for supporting traceability of "basic" and "certified" material along the wine production chain

Four main categories of propagative material in the European Union (EU) have been indentified for grapevine: the primary source, pre-basic, basic and certified material. Each type of material has to be periodically assayed for patho- gens and each material stage is intrinsically characterized by increasing risks. Radiofrequency (RFID) can be considered an efficient and durable traceability system to provide retrieval of propagated material or check producer identity. RFID tagging of grapevines of different categories along the production line could establish a durable link between stakeholder and products. To evaluate this approach, histological observations and growth parameters of basic or certified RFID- tagged grapevine were performed, as well as requirement analysis for management of sanitary checks and for traceability of the wine production chain. Basic material can be safety tagged with RFID tags to establish mother plant vineyards; derived certified material can also safely be tagged. No detrimental performance in terms of vegetative growth and bud production were reported for mother plant vineyards from the first year of production life. Requirement analysis made it possible to individuate traceability objectives, materials and stakeholders involved, as well as the RFID-tagging steps and methods to collect sanitary and production data that are useful for traceability purposes.

A possible role of leaf vascular network in heat dissipation in Vitis vinifera L.

Recent studies showed how the density of leaf vascular system can be involved in the performance of physiological parameters. Major veins are commonly elevated in the lower epidermis of the leaf, and this anatomical feature could play a subsidiary role in increasing heat dispersion in the surrounding environment and may help dissipate excess light energy in the leaves. The aim of this study is to analyse the role of the leaf vein network in the heat dissipation process in Vitis vinifera (L.). Major leaf veins were insulated with liquid paraffin and analysed using thermal imaging. A significantly higher temperature was found on the leaf tissues with insulated veins compared to untreated leaves. Further studies are required to assess the real contribution of the leaf vascular network in thermal dissipation.

Biosecurity of kiwifruit plants: effects of internal microchip implants on vines for monitoring plant health status

Abstract The sanitary condition and traceability of kiwifruit cuttings can represent a key point for pest control in the production of planting material. In recent years there has been concern about the rise of bacterial canker and thus investigation of systems to improve plant biosecurity. Radio frequency identification (RFID) microchips were implanted in 1- or 2-year-old Actinidia deliciosa in order to develop a system for plant traceability able to record health status, certifications or sanitary assay. To assess the health of implanted plants, histological observations were performed, while functional vascular tissue area and mean relative growth rate were evaluated. A small calibre trunk (5–7 mm) did not allow microchip implantation. Conversely, larger trunk diameters seem to sustain microchip positioning. Data reading tests were performed to evaluate the access to sanitary data, and RFID accuracy and reliability were satisfactory. Requirement analysis for the kiwifruit plant nursery chain was performed to help develop a computer-based information system able to record and retrieve sanitary data from each plant. Requirement analysis made it possible to identify traceability objectives, materials and stakeholders involved, as well as RFID-tagging steps and methods to collect information and matching data.