Study on the morphological evolution of bud break in Vitis vinifera L.

The aims are to evaluate morpho-anatomical bud development during dormancy and to compare the heat requirement needed to start bud break in several grapevine cultivars characterised by different geographic origins. A detailed description is presented of the bud growth stages of Vitis vinifera cultivars to contribute to the standardisation of national and international testing systems of fruit growing. Based on the general BBCH-scale, the codes describe the first stages of budbreak in several cultivars with different geographical origins. Dormancy release was evaluated both under natural and forcing conditions, appropriate method to establish the budbreak of deciduous species. The cultivars were characterised in relation to the achievement of complete bud scale opening stage (03 of BBCH scale) which is suggested to consider as an early and indicator of budbreak.

The dam-break problem for concentrated suspensions of neutrally buoyant particles

This paper addresses the dam-break problem for particle suspensions, that is, the flow of a finite volume of suspension released suddenly down an inclined flume. We were concerned with concentrated suspensions made up of neutrally buoyant non-colloidal particles within a Newtonian fluid. Experiments were conducted over wide ranges of slope, concentration and mass. The major contributions of our experimental study are the simultaneous measurement of local flow properties far from the sidewalls (velocity profile and, with lower accuracy, particle concentration) and macroscopic features (front position, flow depth profile). To that end, the refractive index of the fluid was adapted to closely match that of the particles, enabling data acquisition up to particle volume fractions of 60 %. Particle migration resulted in the blunting of the velocity profile, in contrast to the parabolic profile observed in homogeneous Newtonian fluids. The experimental results were compared with predictions from lubrication theory and particle migration theory. For solids fractions as large as 45 %, the flow behaviour did not differ much from that of a homogeneous Newtonian fluid. More specifically, we observed that the velocity profiles were closely approximated by a parabolic form and there was little evidence of particle migration throughout the depth. For particle concentrations in the 52-56 % range, the flow depth and front position were fairly well predicted by lubrication theory, but taking a closer look at the velocity profiles revealed that particle migration had noticeable effects on the shape of the velocity profile (blunting), but had little impact on its strength, which explained why lubrication theory performed well. Particle migration theories (such as the shear-induced diffusion model) successfully captured the slow evolution of the velocity profiles. For particle concentrations in excess of 56 %, the macroscopic flow features were grossly predicted by lubrication theory (to within 20 % for the flow depth, 50 % for the front position). The flows seemed to reach a steady state, i.e. the shape of the velocity profile showed little time dependenc

Evaluation of the effect of esca disease on bud break in Vitis vinifera L.: Possible relationship between cultivars and rootstocks

The aim of this study was to investigate the effect of esca disease on bud break of grapevine in relation to different rootstock combinations. For this purpose under field conditions observations of flower bud phenological stages were carried out on three widespread grapevine cultivars 'Cabernet Sauvignon', 'Sangiovese' and 'Trebbiano toscano'. Further phenological observations were recorded under forcing conditions using 'Cabernet Sauvignon' as the most susceptible to esca disease. Each cultivar was grafted on K5BB, 1103P and own rooted. The plants were infected by esca due to the natural presence of fungi in the vineyard. Results showed that esca disease significantly delayed bud break of symptomatic vines for several years. Grapevines on different rootstocks showed different bud break changes, in particular those on K5BB were the most susceptible to esca.

Gas Exchange, Stem Water Potential and Xylem Flux on Some Grapevine Cultivars Affected by Esca Disease

The effect of esca disease on gas exchange, stem water potential and xylem flux of adult grapevines of CabernetSauvignon, Sangiovese and Trebbiano cultivars was studied over three growing seasons. Water relations weremeasured at véraison and cluster ripening on three types of vines: i) healthy (control); ii) symptomatic and iii)apparently healthy in the year of measurements but that had showed esca symptoms in the previous season. Xylemflux was determined on cane segments by perfusion using a tracing dye before and after the appearance of escasymptoms. Esca induced a marked reduction (about 70%) in carbon assimilation and stomatal conductance,especially in Cabernet Sauvignon and Sangiovese. Esca did not affect the stem water potential. Gas exchangeparameters measured before the symptoms appeared in plants affected by esca were similar to those of healthyplants. Measurements made one month before the appearance of the symptoms cannot be used as screening methodto determine whether the vine will show esca. No differences in dye translocation were found before the symptoms’appearance. However, a decrease in xylem flux was measured in symptomatic vines of Cabernet Sauvignon. Afterthe appearance of esca symptoms, only the Trebbiano had a lower xylem flux than the healthy vines

Esca symptoms appearance in Vitis vinifera L.: influence of climate, pedo-climatic conditions and rootstock/cultivar combination

This study investigated the appearance of esca symptoms in relation to environmental factors and the rootstock/cultivar combination in an experimental setting between 2004 and 2009. Among the common genotypes showing susceptibility to the esca disease, four cultivars were considered: ‘Cabernet Sauvignon’, ‘Sangiovese’, ‘Trebbiano Toscano’ and ‘Chardonnay’. These cultivars were studied own-rooted and in combination with two rootstocks: Kober 5BB and 1103 Paulsen. The difference in susceptibility of cultivars to esca appeared negatively related to the graft. No clear relation was found between esca appearance and environmental factors. Moreover, an unexpected discordance between esca incidence percentage and mortality rate was observed.

Crack growth behavior of SBR, NR and BR rubber compounds: comparison of Pure-Shear versus Strip Tensile test

Fatigue crack growth experiments on different carbon black–filled rubber compounds have been carried out to evaluate the influence of pure-shear and strip tensile testing mode by using sine and pulse as waveforms. In a previous set of experimental investigations regarding the influence of both waveform and tested material, it was found that the mode I of crack opening sometimes propagates too quickly to be properly monitored in tests involving strip-tensile specimens. An alternative test methodology based on pure-shear test mode has been investigated, optimizing both the shape of the specimen and the test equipment. Data obtained from the different compound formulations were consistent with the theoretical background and resulted in similar ranking of compound crack growth resistance for the two testing modes; in addition, pure-shear mode showed a higher sensitivity to formula variations

Calcareous Nannofossil and Calpionellid calcification events across Tithonian \u2013 Berriasian time interval and low latitudes paleoceanographic implications.

The Tithonian-Berriasian time interval is characterized by a major calcareous nannofossil speciation episode and by the appearance of calpionellid group: several genera and species first appear and evolve, showing an increase in diversity, abundance and particularly in calcification degree. This time interval is also characterized by a significant low latitudes increase of carbonate-rich sediments (Rosso ad Aptici fm. toward Maiolica fm.). Calcareous nannofossil and calpionellid biostratigraphy and absolute abundances have been performed on low latitudes selected sections in order to reconstruct biogenic calcite palaeofluxes. Calpionellid has been investigated on thin sections (25\u3bcm thick), while calcareous nannofossil on the same thinnered thin sections (up to 7\ub5m thick) used for calpionellid. All specimens have been counted on 1 cm2 of thin section or 1 mm2 of ultra-thin section respectively for calpionellid and calcareous nannofossil. Paleofluxes have been obtained integrating absolute abundance with single speciment mass weigh (10-12gr of calcareous carbonate) per area unit (cm2) per time unit (yr). Calcareous biogenic paleofluxes point out a link between the lithologic changes and calcified plankton evolution across the Tithonian \u2013 Berriasian interval. During Lower Tithonian (Rosso ad Aptici Fm.) a first calcification event is characterized by nannolith (F.multicolumnatus, C.mexicana, P.beckmannii) increase in abundance, size and calcification degree, followed by the occurrence of first calcified calpionellid (Tintinopsella). Across Upper Tithonian to Lower Berriasian (Rosso ad Aptici fm. \u2013 Maiolica transition and Maiolica fm.) a second bigger calcification event is characterized by a dramatic increase of nannoconid abundance and calcification degree reaching lithogenetic amounts, concomitant with a moderate abundance increase of calcified calpionellid (genera Crassicollaria, Calpionella, Remaniella). Linkages between calcareous nannofossil and calpionellid evolutions with geologic, palaeoceanographic or palaeoclimatic events are inferred. The diversification and biomineralization of high-calcified plankton produced a major increase in pelagic carbonate sedimentation due to the onset of paleoenvrionmental conditions favorable to calcification. The diversification and proliferation of nannolith and nannoconid, interpreted as inhabitants of the lower photic zone, might indicate the establishment of a thermocline/nutricline in the deep photic zone, suggesting the develope of oligotrophic and stable oceanic conditions. It is also suggested that Tithonian-Berriasian calcified plankton evolution could be controlled by a decrease in pCO2, due to decreased spreading rate and/or increased weathering rate (87Sr/86Sr) and cool climatic conditions, concomitant with a decrease in oceanic Mg/Ca ratio values. Both factors thermodynamically promoted low Mg-CaCO3 and CaCO3 biomineralization supporting calpionellid and calcareous nannofossil abundance and calcification rate increases

Calpionellid and calcareous nannofossil evolution and calcification across Tithonian-Berriasian interval (Tethys Ocean).

The Tithonian-Berriasian interval is characterized by the appearance of calpionellid and by a major calcareous nannofossil speciation episode: several genera and species first appear and evolve, showing an increase in diversity, abundance and calcification degree. Monte Pernice and Torre de Busi sections (Southern Alps, Italy) have been analyzed for calcareous nannofossil and calpionellid biostratigraphy, relative and absolute abundances and to reconstruct biogenic calcite palaeofluxes. Calcareous nannofossils have been investigated on simple smear slides and ultra-thin sections (7-8 \ub5m thick) calpionellids on the same thin sections (20-30 \u3bcm thick). All nannofossil specimens have been counted on 1 mm2 of ultra-thin section; all calpionellid specimens on 1 cm2 of thin sections to reconstruct paleofluxes. In the Tithonian- Berriasian interval all known calcareous nannofossil Zones and corresponding Subzones (Bralower et al., 1989) have been recognized. Chitinoidella, Crassicollaria and Calpionella Zones have been identified (Remane, 1986; Pop, 1994b; Reh\ue1kov\ue1 & Michal\uedk, 1997; Andreini et al., 2007). Quantitative calpionellid and nannofossil analyses point out major changes during the Tithonian \u2013 Berriasian interval: nannolith taxa (F.multicolumnatus, C.mexicana, P.beckmannii) increase in abundance, size and calcification degree in discrete steps across the Lower Tithonian, coeval with the occurrence of first calcified calpionellids (Tintinopsella). Nannoconids and calcified calpionellids (Crassicollaria, Calpionella, Remaniella) increase across the Tithonian/Berriasian boundary reaching lithogenetic abundances: the rise in high-calcified nannoconids roughly corresponds with the Acme of C. alpina spherical forms. The diversification and biomineralization of highly-calcified microplankton produced a major increase in pelagic carbonate sedimentation due to the onset of paleoenvrionmental conditions favorable to calcification