1,721,025 research outputs found
Advancements in the study of the grapevine hydraulic strategy under water deficit in relation to the formation of embolism
No full textIn recent years, the validity of embolism quantification methods has been questioned, especially for long-vesseled plants, as some studies have suggested that cutting xylem while under tension (even under water) might generate artificial cavitation. Accordingly, a rehydration procedure prior to hydraulic measurements has been recommended to avoid this artefact. On the other hand, concerns have been raised that xylem refilling might occur when samples are rehydrated. Recently we have proposed an improved method for reliable quantification of this phenomenon in grapevine petioles in which the inclusion of a short-time (20 min) xylem tension relaxation prior to the hydraulic measurement resulted in reliable quantification of native embolism. Much longer periods of hydration (overnight) were required before xylem refilling was observed to occur. This method yielded xylem vulnerability curves similar to the ones obtained using direct microCT visualization and the values were lower than the ones found in samples harvested under native tensions. The new protocol revealed cavitation in grapevine petioles occurs only after significant stomatal conductance reduction, contrary to what was previously hypothesized. In field-grown vines, over 85% of stomatal closure occurred at less negative xylem tension than that required to induce 12% loss of conductivity (PLC). These findings indicate that grapevines regulate their stomata to prevent xylem embolism and would even shed a large proportion of their leaves in order to avoid cavitation tensions. This pattern of stomatal behavior is more consistent with a strategy of cavitation resistance and avoidance, rather than a paradigm of tolerance featuring diurnal cycles of cavitation accumulation and repair
I paesaggi dell’Olivo. Una metodica per il loro riconoscimento applicata in Sardegna
No full textIntroduzione. Il Piano Paesaggistico della Sardegna (2006) ha, sinora, interessato la sola fascia costiera, articolata in 27 Ambiti di paesaggio cui si aggiungono nelle aree interne ulteriori 24 Ambiti che attendono di essere descritti e normati.
Materiali e metodi. Il riconoscimento, nei 24mila Km2 del territorio regionale, di tessere elementari subordinate agli ambiti del PPR è stato realizzato, in ambiente GIS, stratificando all’Uso del Suolo della regione Sardegna (2008), gli shape della Carta Pedologica (con substrato litologico), ricorrendo, per i casi dubbi, a verifiche in loco. L’analisi ha delimitato unità omogenee per tipologia di copertura spingendosi sino al quinto livello dell’UDS RAS. Il successivo arricchimento in conoscenze del singolo paesaggio agrario locale (PAL) è ottenuto sovrapponendo ulteriori db.
Risultati. L’analisi ha individuato 258 PAL con superfici comprese tra 118÷48.662 ettari, in funzione dell’uniformità o eterogeneità dell’uso del suolo e del substrato litologico. I PAL caratterizzati dalla prevalente presenza dell’oliveto sono 11, in 7 l’oliveto è la seconda classe UDS più rappresentata e in 15 la terza.
Conclusioni. La metodologia ha consentito di riconoscere undici ambiti elementari di paesaggio caratterizzati dalla coltivazione dell’olivo per una superficie complessiva di 17.306 ha su una superficie totale di 48.778 presenti sull’intera Isola secondo l’UDS 2008 e rispetto ai 36.468 attribuiti dall’Istat (2010) alla coltura. La progettazione di interventi di valorizzazione sarà facilitata dalla possibilità di poter calare speditamente sui poligoni ulteriori strati informativi
Produzioni animali e bioeconomia
No full textAnimal productions constitute a fundamental pillar of the bioeconomy. The sustainability and circularity of the agricultural and food production systems at the global, European and national levels is based on the transformation of part of the plant-derived productions into animal products. Medium- and long-term estimations agree on the increasing trend of the global request of animal derived proteins. Animal production systems are evolving to find novel solutions to reduce their environmental footprint and to increase their production efficiency
Componenti della produttività ed effetto del-l’irrigazione sulla cascola pre-raccolta dei frutti in olivi della cultivar Frantoio
Full text linkGli effetti dell’irrigazione sulla cascola pre-raccolta dei frutti e sulle componenti produttive dell’olivo sono stati valutati in un esperimento condotto in un oliveto (Olea europaea L., cv Frantoio) intensivo di 6 anni di età. La piena restituzione del fabbisogno idrico dell’albero (PI) durante tutto il periodo irriguo è stata confrontata con un’ir-rigazione di soccorso (IS). Settimanalmente è stato misurato il peso fresco del frutto, l’indice di maturazione e il conte-nuto in olio nella polpa. La raccolta è stata effettuata 142 giorni dopo la piena fioritura (GDPF), ad eccezione di 3 alberi per tesi raccolti 185 GDPF. A partire da 106 GDPF, e per ogni settimana fino a 185 GDPF, sugli alberi selezionati per una raccolta tardiva è stata misurata la cascola dei frutti, distinta tra cascola fisiologica e causata da B. oleae. I frutti degli alberi IS hanno mostrato un minor peso fresco durante tutto il periodo irriguo (-24%) e un maggior indice di matu-razione alla raccolta di ottobre (+25%) rispetto agli alberi PI. Non sono emerse differenze significative tra le tesi in merito al contenuto in olio nella polpa. Le produzioni ad albero nella tesi PI sono state superiori di circa il 30%rispetto a quelle degli alberi IS. A partire da 163 GDPF, e fino alla seconda raccolta, le maggiori percentuali di casco-la sono state misurate sugli alberi sottoposti ad irrigazione di soccorso. Tale cascola, prevalentemente fisiologica, è imputabile al crescente livello di stress idrico subito dagli alberi in asciutto nel corso del periodo estivo. Al contrario, la piena irrigazione ha comportato un maggior livello di infestazione di B. oleae, stimata come % di frutti con foro d’uscita, sulle produzioni alla raccolta 142 GDPF. Considerando il regime irriguo e le perdite legate alla cascola, il periodo di raccolta utile per ottenere produzioni superiori al 90% della produzione massima stimata è stato compreso tra i 263 e i 298 e tra i 273 e i 295 GDPF per la tesi PI e IS, rispettivamente
Stomatal and hydraulic water transport factors in mycorrhizated olive trees
No full textWater uptake and transport are complex processes
affected by root hydraulic conductance and water utilization,
as mediated by leaf. Arbuscular mycorrhizal (AM)
fungi may colonize roots and regulate stomatal behaviour
contributing to the overall water economy of the tree.This
study test whether AM colonisation has a beneficial effect
on total root hydraulic conductance and leaf gas exchange
parameters in olive trees both well irrigated and under
drought.Approx. 20 2-year old potted olive trees were inoculated
with Glomus intraradices, 10 inoculated trees were
kept well irrigated (WI) while the remaining were allowed
to dry up (D) till a value of -2 MPa predawn leaf water
potential (Y). Additional 20 trees were not inoculated and
served as control.Hydraulic conductance (K, kg s-1 MPa-1)
was determined by a HCFM (Dynamax, Inc. USA) (0.1-
0.5 MPa of applied pressure). Leaf transpiration (E), assimilation
(A) and stomatal conductance (gs) was appraised
through the LI-6400 (Li-Cor Inc., NE, USA).Drought in
non-inoculated trees induced a decline of midday K from
1.1±0.1 (SE) to 0.9±0.1 kg s-1 MPa-1, AM fungi maintained
K stable or even higher at 1.3±0.1 kg s-1 MPa-1 (inoculated
D trees). A positive impact on hydraulic transport (~23%
increase of K) was also detected in mycorrhizated WI
trees.In WI trees, average daily A remained similar in control
and mycorrhizated trees (~ 4 mmol CO2 m-2 s-1), concomitantly
it was registered a significant reduction of E
and gs in mycorrhizated WI trees compare to non
mycorrhizated WI. In D trees, a similar response of E and
A was detected, while gs was not clearly affected by
AM.This study revealed that AM may regulate both K and
some gas exchange parameters in both WI and D olive
trees and that the fungi improved the water use efficiency
at leaf scale. It could be concluded that knowledge and
improvement of soil biodiversity level (including AM)
through sustainable practices may be in favour of an optimal
water use in agriculture
Morpho-anatomical adaptations of Callistemon citrinus to CaCl2 and NaCl solutions
No full textAbiotic stress such as salinity is the major abiotic stress that reduce plant growth worldwide, especially in semi-arid regions. Ornamental plants are classified as tolerant species due to their ability to adapt under salt stress conditions. However, most studies concerning the salt tolerance of ornamental species have been based on studies in which NaCl is the predominant salt, whereas information is lacking concerning the CaCl2 effects on morphological, physiological and anatomical adaptations of ornamentals. The aim of this study was to assess the adaptation/tolerance of green house grown Callistemon citrinus an important potted flowering shrub in terms of plant growth, leaf water potential, leaf gas exchange, leaf anatomy and mineral composition, to two chloride salts NaCl and CaCl2. The experiment was performed in terms of equimolar concentrations in order to assess the ion effects of the two salinity sources. Plant growth parameters such as leaf area, leaf number, shoot and root dry weight were negatively affected by salinity, with more pronounced effects recorded under CaCl2 irrigation. The growth reduction was related to a significant decrease of the photosynthetic rate and stomatal conductance. A reduction of stomata size and palisade tissue size was also observed under NaCl irrigation. The differential responses of Callistemon citrinus plants to water salinity by CaCl2 or NaCl elicited several considerations. Other than the ion imbalance, in the CaCl2 treatment ion toxicity might have played a major role on the growth and Pn rate, since the amount of Cl ions accumulated in the leaves of these plants was doubled compared to NaCl treated ones. The adaptation mechanisms developed by the plant to cope with the salinity stress conditions are more effective under NaCl, such as the increased density of glands and trichomes
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