Investigations on anomalies of ovule development and on pollination in mutated grapevines, cv. Barbera

In order to point out the reasons for reduced fertility in tetraploid and 2n-4n periclinal chimera grapevines, ovule development and pollination shown by these plants were investigated.Anomalies in embryo sac formation and non-fertilization, mainly due to difficulties in pollination, were observed and related to fertility

In ovulo embryo culture of stenospermocarpic grapes

Ovules of 14 seedless cultivars, collected 41-49 d after anthesis, were excised and in vitro cultured on 2 different media: NN + 1 µM GA3 + 10 µM IAA and NN + 1 µM GA3 + 20 µM IAA + 2 g/l activated charcoal. Plant development occurred at variable rates; the best percentages were found in Flame Seedless, Perlon, Imperatrice, Carina, Perlette and Ruby Seedless. Genotype resulted to be the main factor affecting ovule response to culture, but also the medium and the interaction genotype x medium influenced it. The addition of 2 g/l activated charcoal to the medium, tested on the cv. Perlette, and the type of added auxin (IBA, IAA, NAA), tested on the cvs Perlette and Sultanina, enhanced plantlet development

Control of sucker growth on Vitis vinifera cv. Merlot with NAA derivatives

Six NAA esters (three known, three newly synthesized) were tested for the grapevine sucker control. Good results were achieved by E4, E5, E9 (8 % concentration) but E3 presented solubility problems. Suckering was reduced also in the second year, without repeating the treatment

Osservazioni sulla meiosi in cellule madri del polline di Vitis vinifera L. (cv. Barbera) diploide e tetraploide

Sono state osservate in Barbera diploide e mutato (tetraploide e chimera periclinale 2n-4n) le varie fasi della meiosi a partire dalle cellule madri del polline fino alla formazione del polline stesso.E' stata evidenziata una certa incidenza di appaiamenti anomali in entrambi i mutanti e, al termine della meiosi, si sono potuti osservare tetradi con granuli soprannumerari. Il polline delle piante mutate, presentante per lo più 4 pori, possiede una capacità germinativa ridotta rispetto al testimone.Investigations on meiosis in pollen mother cells of diploid and tetraploid Vitis vinifera L. cv. BarberaThe different stages of meiosis have been investigated in diploid and mutated Vitis vinifera cv. Barbera (a tetraploid and a periclinal chimera 2n-4n) concerning the pollen mother cells.Some incidence of anomalous coupling in both mutants has been pointed out, and tetrades with extra grains can be observed at the end of meiosis.Pollen grains from mutated plants have generally 4 pores and show with respect to the control a reduced germinability

Osservazioni su due casi di poliploidia indotta in Vitis vinifera L. (cv. Barbera)

Vengono descritti gli aspetti citologici ed istologici di due viti cv. Barbera irraggiate con CO60 e present anti fenotipo poliploide.Le analisi compiute hanno riguardato il conteggio dei cromosomi negli apici radicali, l'osservazione degli strati epidermico e subepidermico delle gemme ibernanti, dei granuli pollinici, degli stomi, delle cellule dell'epidermide degli acini.Da tali osservazioni è emerso che un individuo è totalmente tetraploide, mentre il secondo è una chimera periclinale del tipo 2n-4n.Investigations on two cases of induced polyploidy in Vitis vinifera L. (cv. Barbera)The authors describe cytological and histological aspects of two grapevine plants, cv. Barbera, previously irradiated with CO60 and showing polyploid phenotype.The number of chromosomes in the root tip cells, the two first meristematic layers of wintering buds, the size of pollen grains, stornata, and epidermal cells of berries were investigated.The results show that one of them is a tetraploid grape, while the other was found to be a 2n-4n periclinal chimera

Measurements and tests on FBK silicon sensors with an optimized electronic design for a CTA camera

In October 2013, the Italian Ministry approved the funding of a Research & Development (R&D) study, within the "Progetto Premiale TElescopi CHErenkov made in Italy (TECHE)", devoted to the development of a demonstrator for a camera for the Cherenkov Telescope Array (CTA) consortium. The demonstrator consists of a sensor plane based on the Silicon Photomultiplier (SiPM) technology and on an electronics designed for signal sampling. Preliminary tests on a matrix of sensors produced by the Fondazione Bruno Kessler (FBK-Trento, Italy) and on electronic prototypes produced by SITAEL S.p.A. will be presented. In particular, we used different designs of the electronics in order to optimize the output signals in terms of tail cancellation. This is crucial for applications where a high background is expected, as for the CTA experiment.Comment: 5 pages, 6 figures; Proceedings of the 10th Workshop on Science with the New Generation of High-Energy Gamma-ray experiments (SciNeGHE) - PoS(Scineghe2014)00

Search for gamma-ray bursts in the GeV energy range at Mt. Chacaltaya (5200 m)

Observations of gamma-ray bursts in the 1 GeV–1 TeV energy region are of great interest for the understanding of these mysterious events. The detection of GeV-TeV gamma-ray bursts is feasible using extensive air shower arrays monitoring the fluctuations of the single-particle counting rate. The sensitivity is strongly increased working at mountain altitudes, in particular above 5000 m. In this paper we discuss the possibility to exploit the existing BASJE EAS array operating at Mt. Chacaltaya (Bolivia) at 5200 m a.s.l. Simulations of electromagnetic showers in the atmosphere have been performed in order to evaluate the sensitivity of this experiment to detect gamma ray bursts of different time duration, spectrum slope and energy cut-off. The detector can observe events of energy fluence F(ED1 GeV )A few 1025 erg cm22, comparable to that measured by satellite instruments during the most intense gamma-ray bursts, provided they occurr at low zenith angles and assuming that the energy spectrum at least extends up to A1 TeV. In the case of events below the sensitivity of the experiment, upper limits on the high-energy tail of the spectrum can be obtained by measurements in coincidence with satellite observations

A Search for Ultra-High Energy Counterparts to Gamma-Ray Bursts

A small air shower array operating over many years has been used to search for ultra-high energy (UHE) gamma radiation ($\geq 50$ TeV) associated with gamma-ray bursts (GRBs) detected by the BATSE instrument on the Compton Gamma-Ray Observatory (CGRO). Upper limits for a one minute interval after each burst are presented for seven GRBs located with zenith angles $\theta < 20^{\circ}$. A $4.3\sigma$ excess over background was observed between 10 and 20 minutes following the onset of a GRB on 11 May 1991. The confidence level that this is due to a real effect and not a background fluctuation is 99.8\%. If this effect is real then cosmological models are excluded for this burst because of absorption of UHE gamma rays by the intergalactic radiation fields.Comment: 4 pages LaTeX with one postscript figure. This version does not use kluwer.sty and will allow automatic postscript generatio

INFN Camera demonstrator for the Cherenkov Telescope Array

The Cherenkov Telescope Array is a world-wide project for a new generation of ground-based Cherenkov telescopes of the Imaging class with the aim of exploring the highest energy region of the electromagnetic spectrum. With two planned arrays, one for each hemisphere, it will guarantee a good sky coverage in the energy range from a few tens of GeV to hundreds of TeV, with improved angular resolution and a sensitivity in the TeV energy region better by one order of magnitude than the currently operating arrays. In order to cover this wide energy range, three different telescope types are envisaged, with different mirror sizes and focal plane features. In particular, for the highest energies a possible design is a dual-mirror Schwarzschild-Couder optical scheme, with a compact focal plane. A silicon photomultiplier (SiPM) based camera is being proposed as a solution to match the dimensions of the pixel (angular size of ~ 0.17 degrees). INFN is developing a camera demonstrator made by 9 Photo Sensor Modules (PSMs, 64 pixels each, with total coverage 1/4 of the focal plane) equipped with FBK (Fondazione Bruno Kessler, Italy) Near UltraViolet High Fill factor SiPMs and Front-End Electronics (FEE) based on a Target 7 ASIC, a 16 channels fast sampler (up to 2GS/s) with deep buffer, self-trigger and on-demand digitization capabilities specifically developed for this purpose. The pixel dimensions of $6\times6$ mm$^2$ lead to a very compact design with challenging problems of thermal dissipation. A modular structure, made by copper frames hosting one PSM and the corresponding FEE, has been conceived, with a water cooling system to keep the required working temperature. The actual design, the adopted technical solutions and the achieved results for this demonstrator are presented and discussed.Comment: In Proceedings of the 34th International Cosmic Ray Conference (ICRC2015), The Hague, The Netherlands. All CTA contributions at arXiv:1508.0589