Potassium deficiency and drought stress in grapevine cultivars

Potassium availability affects drought responses in plants through several metabolic roles, among which stomatal regulation, cell growth and xylem hydraulics. Vitis vinifera L. is a highly valuable crop and several genotypes have been selected during its millennial cultivation. Varieties show differences in their adaptability to stress conditions, making them more or less suitable to certain climatic and edaphic conditions. The varieties cultivated in Sicily are characterized by high variability. We investigated the response of two Sicilian cultivars (Nero d'Avola and Catarratto) to potassium deficiency and drought stress. Two-year-old grafted plants were grown in agriperlite, with or without potassium in the fertigation solution, and subjected to moderate drought stress by suspending irrigation for 6-8 days. Potassium content of xylem sap, leaf and root tissues were measured with an ion-selective electrode. Changes in stomatal conductance, plant transpiration and hydraulic conductance were compared between genotypes and treatments, in order to gain information for the development of optimal fertigation practices and the selection of the most drought tolerant varieties

ETHICS AND AGING: FOCUS ON LIVING WILL FOR PATIENTS WITH DEMENTIA

Today dementia certainly represents a public health priority with a huge global impact on wordwide population. However, clinical and social issues related to demen-tia have long been marginalized. The actual high prevalence of dementias requires also to face issues from a bioethical perspective, regarding how to deal with demented patient\u2019s disposition. There are currently no specific guide-lines on the national territory regarding whether to draw up a living will by a patient with dementia, neither about the informa-tive role of physicians during the progres-sive story of the disease

A Community-Based Multicenter Trial of Pharmacokinetically Guided 5-Fluorouracil Dosing for Personalized Colorectal Cancer Therapy

Pharmacokinetically guided (PK-guided) versus body surface area-based 5-fluorouracil (5-FU) dosing results in higher response rates and better tolerability. A paucity of data exists on PK-guided 5-FU dosing in the community setting

Young Women With Type 1 Diabetes Have Lower Bone Mineral Density That Persists Over Time

OBJECTIVE—Individuals with type 1 diabetes have decreased bone mineral density (BMD), yet the natural history and pathogenesis of osteopenia are unclear. We have previously shown that women with type 1 diabetes (aged 13–35 years) have lower BMD than community age-matched nondiabetic control subjects. We here report 2-year follow-up BMD data in this cohort to determine the natural history of BMD in young women with and without diabetes

Design and Digital Fabrication of a Parametric Joint for Bamboo Sustainable Structures

The study deepens the design of a joining system for bamboo spatial structure by proposing new and advanced solutions that guarantee maximum freedom of composition to the designer. The joint allows to determine and control parametrically the adaptability to any spatial grid configuration of culms with heterogeneous dimensions. Despite the bamboo being one of the main natural building materials in the field of sustainable architecture, currently, it is not used enough due to the lack of adequate connection systems. Bamboo is a rapidly growing renewable resource, naturally available, which is quite strong and lends itself to structural applications. The paper proposes an innovative approach to architectural design by parametric modelling techniques developed in recent years in parallel with advances in the field of computational geometry. The 3D prototyping of different types of joints and the architectural-compositional design of a temporary structure, destined to be used as an exhibition pavilion, have made it possible to validate the technological solution defined

Does short-term potassium fertilization improve recovery from drought stress in laurel?

Xylem hydraulic conductance varies in response to changes in sap solute content, and in particular of potassium (K+) ion concentration. This phenomenon, known as the \u2018ionic effect\u2019, is enhanced in embolized stems, where it can compensate for cavitation-induced loss of hydraulic conductance. Previous studies have shown that in well-watered laurel plants (Laurus nobilis L.), potassium concentration of the xylem sap and plant hydraulic conductance increased 24 h after fertilization with KCl. The aim of this work was to test whether water-stressed laurel plants, grown under low potassium availability, could recover earlier from stress when irrigated with a KCl solution instead of potassium-free water. Two-year-old potted laurel seedlings were subjected to water stress by suspending irrigation until leaf conductance to water vapour (gL) dropped to 3c30% of its initial value and leaf water potential (\u3c8L) reached the turgor loss point (\u3c8TLP). Plants were then irrigated either with water or with 25 mM KCl and monitored for water status, gas exchange and plant hydraulics recovery at 3, 6 and 24 h after irrigation. No significant differences were found between the two experimental groups in terms of \u3c8L, gL, plant transpiration, plant hydraulic conductance or leaf-specific shoot hydraulic conductivity. Analysis of xylem sap potassium concentration showed that there were no significant differences between treatments, and potassium levels were similar to those of potassium-starved but well-watered plants. In conclusion, potassium uptake from the soil solution and/or potassium release to the xylem appeared to be impaired in water-stressed plants, at least up to 24 h after relief from water stress, so that fertilization after the onset of stress did not result in any short-term advantage for recovery from drought