A Progress report on citrus rootstocks studies in Sardinia

This paper reports further results of long-term research on citrus rootstocks in Sardinia started in 1969. Two rootstocks (sour orange and « Troyer » citrange) have been compared for « Hamlin » and « Frost Navel » sweet oranges, and «Frost Eureka» lemon. Five rootstocks (sour orange, « Troyer» citrange, «Rubidoux» trifoliate orange, « Orlando» tangelo, and « Palestine» sweet lime) were also compared for « Frost Marsh» grapefruit. The growth and productivity for all of the stock/scion combinations were evaluated from 1973 to 1977. The results showed that both growth and productivity of «Frost Navel» orange were better on «Troyer» citrange than on sour orange. «Hamlin» orange productivity was also improved by « Troyer» citrange, while sour orange increased the tree-growth. In « Frost Eureka» lemon both growth and productivity were increased by sour orange. The fruit quality was normally improved by «Troyer» citrange in comparison with sour orange. The growth and fruit production of «Frost Marsh» grapefruit were mainly increased by «Orlando» tangelo and «Palestine» sweet lime. Intermediate growth and productivity were found on sour orange and «Troyer» citrange. The lowest growth and yield were recorded on « Rubidoux» trifoliate orange, but it and « Troyer» citrange improved fruit quality

Phytotoxic metabolites produced by Botryosphaeriaceae involved in grapevine trunk diseases

Fungi belonging to the Botryosphaeriaceae family are well known as cosmopolitan pathogens, saprophytes and endophytes and occur on a wide range of hosts including grapevine. More recently, a new species of Lasiodiplodia was isolated from declining grapevines in Sardinia (Italy). This still undescribed species showed to produce in liquid culture several phytotoxic secondary metabolites. In this communication the chemical and biological characterization of these bioactive secondary metabolites is discussed together with their role in the pathogenesis process

<i>Botryosphaeriaceae</i> species associated with cankers and dieback of grapevine and other woody hosts in agricultural and forestry ecosystems

Species of Botryosphaeriaceae have a cosmopolitan distribution and are known to cause serious diseases with dramatic economic implications in both agricultural and forestry ecosystems. In recent years, epidemic attacks of Diplodia and Neofusicoccum species have gradually increased in Sardinia on different hosts such as holm oak, cork oak and Juniper. Considering the plurivorous nature of many Botryosphaeriaceae species and the little information available on their geographic distribution, host range and genetic variability in Sardinia, it was considered appropriate in this PhD thesis to expand knowledge on five patho-systems by studying taxonomy, morphology, phylogeny and pathogenicity of the main species associated with plant cankers and dieback. Results obtained highlight that more than twenty Botryosphaeriaceae species occur on declining plants in both agricultural and forestry ecosystems. Among these, three species Diplodia subglobosa, Lasiodiplodia exigua and Lasiodiplodia mediterranea, morphologically and phylogenetically (ITS and EF1-&#945; sequences data) distinct from all other known species, are described and illustrated herein. Finally, this study showed that species belonging to the Botryosphaeriaceae family currently represent a serious threat to the biodiversity of Sardinian natural ecosystems and can strongly affect the quality and quantity of the produce yielded

Variazioni stagionali del potenziale idrico fogliare, osmotico e di pressione nel grano duro

In 1982 the seasonal changes of leaf Ψ, Ψs and Ψpof five durum wheat cultivars grown under field conditions was monitored using a psycrometric apparatus. There was found to be a general increase in pressure during the floreal differentiation-earing period. No particular differences were observed either between the tall and dwarf varieties or between those with bloom or not. The relation between the values ot Ψp and leaf Ψ, taken from the earing period to the inltial stage of leaf senescence das not fallow a linear regression in all the varieties. According to an analysis of the differing values of Ψ p and Ψ, it seems that the varieties «Tibula» and «Creso» are more resistant to water stress than the other varieties, although these findings require further convalidation

Risposta produttiva del mais e del sorgo agli stress idrici indotti in diverse fasi del ciclo biologico

During 1982 a comparative test was conducted between a maize hybrid and a sorghum hybrid of similar growing cycle duration, to study the effect of water stress induced during various phases of the biological cycle. Yield response and the analysis of physiological parameters confirm the higher resistence of sorghum to water stress presumably through mechanisms of osmotic adjustment. Nel corso del 1982 è stata attuata una prova di confronto tra un ibrido di mais e di sorgo di simile durata del ciclo colturale al fine di studiare gli effetti dello stress idrico indotto in diverse fasi del ciclo biologico. I risultati produttivi e l'analisi dei parametri fisiologici presi in considerazione confermano la superiore capacità del sorgo ad "adattarsi" a condizioni di limitata disponibilità idrica del terreno, presumibilmente attraverso meccanismi di aggiustamento osmotico. Nel mais da granella i decrementi di produzione sono risultati simili sospendendo temporaneamente le erogazioni idriche o durante la fase di levata o di maturazione lattea. Si rileva, infine, che con ottimali disponibilità idriche, il mais ha confermato la sua superiorità produttiva nei confronti del sorgo

Effetti della densità di semina e della concimazione azotata sulla produzione del triticale

In the year 1981-82 a factorial trial of nitrogen fertilization (80, 120, 160, kg ha-1of N) and sowing rates (300, 350, 400 viable seeds per m2) has been carried out on three triticale lines in two environments of Sardinia (Oristano and Sassari). Equal N rates have been applied to a durum wheat at 350 sowing rate. The limited water availability in the soil, especially during the grain filling, has negatively affected the DM accumulation processes more markedly in the high ear n. per m2 thesis. In both sites the n. of plants increased with increase in seed rates and there was a greater correspondence between theoretical and reaI density at Oristano. Indipendently of the varieties and N rates, at Sassari yields have been slightly increasing with increase in sowing rates to which variations in the ear n. per m2 correspond in the same way, while at Oristano significant production increase has been achieved only by N80 rate owing to the seed rate. At Sassari, indipendent of sowing rates, triticale grain yields have been slightly increasing with increase in N rates. At Oristano production variation has not been achieved with lower sowing rates, decrease has been observed with more then N 80 kg ha-1 at higher sowing rate. A slightly higher triticale grain production compared with durum wheat has been achieved restricted to Oristano

Influenza della posizione degli erogatori sulle componenti dello sviluppo e della produzione nell'arancio «Valencia»: risultati preliminari

In this study two irrigation systems (drip and microjet) and different positions of emitters were compared in a young «Frost Valencia» orange grove. The following irrigation treatments were set out: - two drippers (4 l/h each) per tree at apposite distance of 1 m trom the trunk: - two drippers (4 l/h each) per tree at apposite distance of 0.5 m from the trunk; - two microjets (65 l/h) per tree at apposite distance of 0.2 m from the trunk. Both the irrigation systems were able to wet a 3 m strip of soil along the rows, while thc central part of interrows was kept dry. Among the wet area drip irrigation induced different soil moisture pattern, since the soil moisture percentage was greater near the emitters (more than the «field capacity») and particularly at 50 cm depth; and decreased as the distance trom the drippers increased. The water distribution under the microjets resulted more uniform and the soil moisture reached the highest values at 25 cm soil depth, alwais close to the emitters. Leaf water potential and leat diffusive resistance measured at different times did not show any symptom af water-stress, while trunk growth resulted not affected by different irrigation treatments

Shear zone development and structurally-controlled skarn ore mineralization in the Rosas district, SW Sardinia.

The Rosas Shear Zone (RSZ) is a 1 km thick brittle-ductile shear zone that outcrops in the Variscan fold and thrust belt foreland of SW Sardinia, where several important ore deposits were mined in the last century. The RSZ lies in the footwall and strikes parallel to the NE-dipping regional thrust that separates the Variscan foreland from the nappe zone. Two thrusts that developed along the limbs of two km-scale overturned antiforms, with NE-dipping axial plane, bound the RSZ. The folds show a SW-facing direction and a well-developed axial plane cleavage, and affect a lower Cambrianupper Ordovician stratigraphic succession mainly made, from bottom to top, by a sequence about 200 m thick of dolostones and massive limestone followed by 50 m of marly limestones overlain by about 150 m of sandstones, pelites and siltstones, finally unconformable capped by conglomerates and siltstones, ranging in thickness from a few to 200 m. Differently, within the RSZ the bedding is completely transposed along the cleavage and its internal structure is characterized by anastomosing thrusts that affect the stratigraphic succession defining map-scale slices mainly consisting of dolostones and limestones embedded into the siliciclastic formations. It is noteworthy the occurrence of a NE-dipping, up to 100 m thick gabbro-dyke that postdates the deformation phases and that can be related to the exhumation of the chain during late Carboniferous-Permian times. In the whole area, contact metamorphic and metasomatic processes selectively affected the Cambrian carbonate tectonic slices, originating several skarn-type orebodies. Mineralized rocks display the mineralogical assemblages and textures of Fe-Cu-Zn skarns, with relicts of anhydrous calcic phases related to the prograde metamorphic stage (garnet, clinopyroxene, wollastonite), frequently enclosed in a mass of hydrous silicates (actinolitic amphibole, epidote) and magnetite related to the retrograde metasomatic stage, in turn followed by chlorite, sulfides, quartz and calcite associated to the hydrothermal stage. Metasomatic reactions also involved mafic rocks, producing a mineral association marked by clinopyroxene, amphibole, epidote, prehnite and Barich K-feldspar. Sulfide ores are made of prevailing sphalerite, chalcopyrite and galena, with abundant pyrite and pyrrhotite and minor tetrahedrite and Ag-sulfosalts. Garnets are andraditic/grossularitic, distinctly zoned and optically anisotropic. Field surveys pointed out the tight structural controls on skarn and ore formation. On a local scale, the gabbro emplacement along high- to low-angle NNW-SSE structures bordering the carbonate tectonic slices accentuate the effects of contact metamorphism, and metric to decametric mineralogical zonation (garnet-&gt;pyroxene-&gt;wollastonite) are recognized. On a larger scale, extensive hydrothermal fluid circulations involved the structures of the RSZ. Infilling of metasomatic fluids in carbonate tectonic slices is fault-controlled and aided by the increase in permeability due to the alteration of prograde silicates. The causative intrusion related to skarn ores belongs to the early Permian (289±1 Ma) ilmenite-series, ferroan granite suite which intrudes the RSZ about 3 km east from the studied area. The Fe-Cu-Zn skarn ores of Rosas are best interpreted as distal, structurallycontrolled orebodies, connected to large-scale circulation of granite-related fluids in the km-sized plumbing system represented by the RSZ

ARMENITE: A REALLY RARE MINERAL?

Armenite is a quite uncommon double-ring Ba-Al-Ca silicate hydrate belonging to the milarite-osumilite group and with the general formula BaCa2Al6Si9O30·2H2O. It generally forms pseudo-hexagonal whitish-pinkish crystals. However, in its structure, Si, Al ordering and H2O positions produce the deviation from hexagonal symmetry, explaining the belonging to the Pnna or Pnc2 space groups. In thin section, armenite is quite elusive. In fact, it appears colorless, with low relief and low first-order interference color. More complication arises from the tartan-like twinning patterns (resembling that of microcline), patchy-like and/or undulose extinction as well as the monoaxial to strongly biaxial (2V up to 65°) behavior. Its affinity to hexagonal or orthorhombic space groups as well as the reasons for its anomalous optical features have formerly been an object of debate. Up to now, armenite has only been found in a dozen of places worldwide, among which Armen mine (Norway), Quebec (Canada), New South Wales (Australia), Scotland, Switzerland, and Sardinia (Italy). It typically forms veins within the host rocks in different geological environments. These include metasomatic basic to intermediate igneous rocks, mineralized skarn and hornfels, and gneisses indicating that the interaction between fluid phases and a primary Ba source is required for its formation. Here we report the third occurrence of armenite in Sardinia, from the Rosas mine area (Mitza Sermentus mineworks, south-west Sardinia). Armenite-bearing samples were collected along the contact between a sulfide-mineralized skarn vein and a black phyllite host-rock. The black phyllite matrix consists of muscovite, chamosite and quartz with feldspars, clinozoisite, titanite, and calcite as accessory phases. The skarn is made up of clinopyroxene, amphibole, epidote, chlorite and wollastonite, and calcite; accessory minerals are titanite, apatite, prehnite, and baryte. The ore minerals mainly consist of galena, sphalerite, chalcopyrite, and pyrite. Armenite is usually concentrated in mm-wide white veinlets along the contact between the sulfide mineralization and the host rock or more rarely dispersed in the phyllite matrix. At first, interpreted as an altered feldspar, it was identified by SEM-EDS analyses. Despite being semi-quantitative, the analyses provided compositions very close to stoichiometric armenite, with SiO2 ~ 48 wt.%, Al2O3 ~ 28 wt.%, BaO ~ 13 wt.% and CaO ~ 10 wt.%. This finding was further confirmed by XRPD analyses on armenite-rich polymineralic samples in which more than 20 peaks were assigned to this phase leading to a good match with an armenite in the PDF database (Ref. code 00-037-0432). Beyond its supposed rarity and its peculiar crystal structure, three reasons make armenite deserving of attention: (i) understanding its genesis could better constrain the P-T-fluid conditions of rocks in which armenite is found and that are often mineralized; (ii) given its difficult recognition by base techniques, it is likely that armenite is more common than previously thought and is usually overlooked; (iii) since its formation requires a primary Ba source, armenite could be used as an indicator of the proximity of Ba-rich deposits

Performances of GPM satellite precipitation over the two major Mediterranean islands

This study aims to assess the reliability of satellite-precipitation products from the Global Precipitation Measurements (GPM) mission in regions with complex landscape morphology. Our analysis is carried out in the European mid-latitude area, namely on the two major islands of Mediterranean Sea, i.e. Sardinia and Sicily (Italy). Both islands experience precipitation originating from the interaction of steep orography on the coasts with winds carrying humid air masses from the Mediterranean Sea. The GPM post real-time IMERG (Integrated Multi-satellitE Retrievals from Global Precipitation Measurement) “Final” run product at 0.1° spatial resolution and half-hour temporal resolution have been selected for the two-year 2015–2016 period. Evaluation and comparison ofthe selected product, withreferenceto raingauge network data, areperformed athourly and daily time scales using statistical and graphical tools. The influences of morphology and land-sea coastal area transition on the reliability of the GPM product have been analysed. Confirming previous studies, results showed that GPM satellite data slightly overestimate rainfall over the study areas, but they are well correlated with the interpolated raingauge data. Metrics based on occurrences above a given threshold and on total volume above the same threshold were applied and revealed better performances for the latter ones. Applying the same metrics we show how GPM performances improve as the temporal aggregation increases. Several drawbacks were detected in the coastal areas, which were characterized by worse performances than internal areas. Statistics are generally very similar for the two considered case studies (i.e., Sardinia and Sicily) except for correlation between topography and accuracy of GPM products, which was slightly higher for Sardinia