Thidiazuron induced somatic embryogenesis in Coffea arabica L. and Coffea canephora P ex Fr.

The rapid direct and repetitive somatic embryogenesis in Coffea arabica and C. canephora genotypes was tested on Murashige and Skoog medium (MS) containing thidiazuron (TDZ) (1-phenyl-3-(1,2,3,-thiadiazol-5-yl)urea) in concentrations of 2.27–11.35s M. Segments taken from cotyledon leaf, first leaf and stalk of regenerated plantlets produced clusters of somatic embryos directly from cut portions of explants on TDZ (9.08 M) containing medium within a period of two months. Subculturing of these embryo clusters produced more secondary embryos on reduced TDZ (0.045–0.91M) containing medium and these subsequently developed into plantlets (80–85%) on development medium followed by rooting on MS basal medium. This direct somatic embryogenesis from leaf and hypocotyl explants in Coffea sp. is a strong evidence of cell totipotency. The rapid somatic embryo induction protocol would be useful for the mass propagation, direct regeneration and genetic transformation of selected elite lines

AgNO3 - a potential regulator of ethylene activity and plant growth modulator

The aim of this review is to critically analyze the role of silver nitrate (AgNO3) in modulating plant growth and development. In recent years, basic studies on ethylene regulation opened new vistas for applied research in the area of micro-propagation, somatic embryogenesis, in vitro flowering, growth promotion, fruit ripening, and sex expression. Silver nitrate has proved to be a very potent inhibitor of ethylene action and is widely used in plant tissue culture. Few properties of silver nitrate such as easy availability, solubility in water, specificity and stability make it very useful for various applications in exploiting plant growth regulation and morphogenesis in vivo and in vitro. Silver ion mediated responses seem to be involved in polyamines, ethyleneand calcium- mediated pathways, and play a crucial role in regulating physiological process including morphogenesis. The molecular basis for regulation of morphogenesis under the influence of silver nitrate is completely lacking. This review compiles published reports of silver nitrate-mediated in vitro and in vivo studies and focuses on fundamental and applied aspects of plant growth modulation under the influence of silver nitrate

Flux profile scanners for scattered high-energy electrons

The paper describes the design and performance of flux integrating Cherenkov scanners with air-core reflecting light guides used in a high-energy, high-flux electron scattering experiment at the Stanford Linear Accelerator Center. The scanners were highly radiation resistant and provided a good signal to background ratio leading to very good spatial resolution of the scattered electron flux profile scans.Comment: 22 pages, 17 figure

Induction of in vitro flowering in Capsicum frutescens under the influence of silver nitrate and cobalt chloride and pollen transformation

The influence of silver nitrate (AgNO3) and cobalt chloride (CoCl2) on shoot multiplication and in vitro flowering in Capsicum frutescens Mill. was investigated. Exogenous administration of AgNO3 and CoCl2 at a concentration of 30 \ub5M resulted in the maximum tissue response in terms of shoot length and number of shoots after 45 days culturing on MS medium. Both silver nitrate (40 \ub5M) and cobalt chloride (30 \ub5M) influenced in vitro flowering after 25 and 45 days respectively. This is the first report on in vitro flowering in C. frutescens. The study also demonstrated successful transformation of pollen obtained from the in vitro flowers. Since capsicum is highly recalcitrant to in vitro plant regeneration, the results of the study may be highly useful in transformation of capsicum using germ free in vitro flowers

Assessment of Deformation Field during High Strain Rate Tensile Tests of RAFM Steel Using DIC Technique

AbstractNnnnTowards developing a constitutive model for describing the flow and fracture behaviour of engineering materials under higher strain rates, studying the deformation fields in uniform and localized deformation regime using the high strain rate tensile tests is of technical importance. To this end, high strain rate tensile tests have been carried out on flat tensile specimen of reduced activation ferritic-martensitic (RAFM) steel at different loading rates varying from 5 m/s to 14 m/s. The strain fields at uniform and localized deformation regime have been mapped by Digital Image Correlation (DIC) technique. For carrying out the DIC, high speed images of the specimen surface have been captured in-situ by high speed camera, synchronized with the load-displacement data acquisition system. The stress-strain fields thus obtained in this study would be an appropriate input to numerical analysis to characterize the flow and fracture behaviour of RAFM steels

Multiwavelength Study of M8.9/3B Solar Flare from AR NOAA 10960

We present a multi-wavelength analysis of a long duration white-light solar flare (M8.9/3B) event that occurred on 4 June 2007 from NOAA AR 10960. The flare was observed by several spaceborne instruments, namely SOHO/MDI, Hinode/SOT, TRACE and STEREO/SECCHI. The flare was initiated near a small, positive-polarity, satellite sunspot at the centre of the AR, surrounded by opposite-polarity field regions. MDI images of the AR show considerable amount of changes in a small positive-polarity sunspot of delta configuration during the flare event. SOT/G-band (4305 A) images of the sunspot also suggest the rapid evolution of the positive-polarity sunspot with highly twisted penumbral filaments before the flare event, which were oriented in the counterclockwise direction. It shows the change in orientation and also remarkable disappearance of twisted penumbral filaments (~35-40%) and enhancement in umbral area (~45-50%) during the decay phase of the flare. TRACE and SECCHI observations reveal the successive activations of two helical twisted structures associated with this sunspot, and the corresponding brightening in the chromosphere as observed by the time-sequence images of SOT/Ca II H line (3968 A). The secondary-helical twisted structure is found to be associated with the M8.9 flare event. The brightening starts 6-7 min prior to the flare maximum with the appearance of secondary helical-twisted structure. The flare intensity maximizes as this structure moves away from the AR. This twisted flux-tube associated with the flare triggering, is found to be failed in eruption. The location of the flare is found to coincide with the activation site of the helical twisted structures. We conclude that the activations of successive helical twists in the magnetic flux tubes/ropes plays a crucial role in the energy build-up process and triggering of M-class solar flare without a CME.Comment: 22 pages, 12 figures, Accepted for Publication in Solar Physic

Continuous Flooding or Alternate Wetting and Drying Differently Affect the Accumulation of Health-Promoting Phytochemicals and Minerals in Rice Brown Grain

Climate changes impose adoption of water-saving techniques to improve the sustainability of irrigated rice systems. This study was aimed, by a two-years side-by-side comparison, at verifying the hypothesis whether \u201cAlternate Wetting and Drying\u201d (AWD) affects the concentrations of health-related compounds and minerals in brown grains of three japonica rice (Oryza sativa L.) cvs (\u2018Baldo\u2019, \u2018Gladio\u2019, and \u2018Loto\u2019) usually grown in temperate areas in continuous flooding (CF). Due to the rotational turns in water distribution imposed by local authorities and to the weather behavior, different AWD timing and severity occurred in the two years of the study. AWD induced in both seasons yield losses in \u2018Baldo\u2019 and \u2018Gladio\u2019 but not in \u2018Loto\u2019. In the brown grains of \u2018Loto\u2019, AWD increased the concentrations of total tocols, \u3b3-oryzanol, flavonoids, and the antioxidant activity. AWD affected the concentrations of minerals, particularly increasing copper, cadmium and nickel, and decreasing manganese, arsenic and zinc. In the sensitive cultivars, \u2018Baldo\u2019 and \u2018Gladio\u2019, AWD seems to affect plant yield, rather than for severity of the dry period, for prolonged absence of ponded water that exposes plants to cooler temperatures. The selection of suitable cultivars, like \u2018Loto\u2019, tolerant to AWD-related stresses, could combine environmental, yield-related, and nutritional benefits improving the product quality

Phytosanitary situation of maize streak virus in the main maize production zones of Cameroon

Open Access Article; Published online: 09 Apr 2021Maize streak caused by the Maize streak virus (MSV, genus Mastrevirus) is transmitted by Cicadulina spp., and is responsible for considerable maize yield losses in all maize production zones in Africa, including Cameroon. A survey was conducted in 3 agro-ecological zones (AEZ) of Cameroon (Sudano-Sahelian: zone I, Western Highlands: zone III and Bimodal Rainforest: zone V) between November 2017 and November 2019 to determine the status of streak disease in maize farms. The incidence and severity were determined in 90 maize fields, 30 fields per AEZ; the effect of lightning on the disease was also assessed using 15 fields under shade and 15 opened fields per AEZ. The highest streak disease incidence (60%) was found in AEZ I, whereas the lowest incidence was 10% in AEZV. The highest disease incidence and severity (80% and 4.5 respectively) were observed in maize fields under shade as compared to open fields (70% and 4.5 respectively). The phylogenetic analysis of MSV sequences from symptomatic plants indicated it as MSV-A strain identical to be previously reported to determine the virus diversity in relation to the other characterization isolates. This information is important for the development of control strategies to limit yield losses due to MSV

(Sub)mm Interferometry Applications in Star Formation Research

This contribution gives an overview about various applications of (sub)mm interferometry in star formation research. The topics covered are molecular outflows, accretion disks, fragmentation and chemical properties of low- and high-mass star-forming regions. A short outlook on the capabilities of ALMA is given as well.Comment: 20 pages, 7 figures, in proceedings to "2nd European School on Jets from Young Star: High Angular Resolution Observations". A high-resolution version of the paper can be found at http://www.mpia.de/homes/beuther/papers.htm