Cyanamide Research Articles

Efficacy of dormex (hydrogen cyanamide) on germination, growth, yield andquality of sugarcane

Sugarcane is propagated by vegetative means using cane pieces containing one, two or more buds. After planting the crop begins with the germination of buds which is a complex phenomenon and differs from other seed plants. Under north Indian conditions, the germination of buds varies from 20–45%. In order to determine the effect of Dormex, a product having hormone like properties, an experiment was conducted at research farm of UP Council of sugarcane Research Institute Shahjahanpur (U.P.) during the spring season of planting 2012–13 using variety CoS 96268. Sugarcane setts were treated for fifteen minutes with different concentrations (i.e, 1.0%, 1.5%, 2.0%) of Dormex before planting to explore its efficacy on bud germination. The results indicated that sugarcane planting with setts treated with Dormex increased the germination significantly at 60 days after planting (DAP). The germination at 30 and 45 DAP was also higher than untreated control. The shoot population was also increased with the application of Dormex at a significant level at 30 days intervals. Increase in number of millable canes and cane height also followed the similar trend upto maturity. The cane yield increased in plots treated with Dormex than untreated control. Quality of cane was not affected significantly due to the application of Domex.

Effect of Hydrogen Cyanamide on Flowering Period and Pollen Germination of Pear Pollinizer

Effect of Hydrogen Cyanamide on Flowering Period and Pollen Germination of Pear Pollinizer

Dormancy removal in pistachio nut: Influences of Hydrogen Cyanamid (Dormex®) as compared to ordinary seed chemical pre-treatments

Seed germination is considered an important phenological stage of plant growth during which the viable, nondormant embryos develop into seedlings under favorable conditions. Currently, various seed priming treatments may be used to enhance germination values (germination percentage, Lag phase, time to reach 50% germination) and breaking dormancy; gibberellins and KNO3 are applied as common treatments in this regard. In the present study, efficacy of Hydrogen Cyanamid (HCN, Dormex®) on seed germination of two cultivated pistachio varieties (Abasali, Shahpasand) were studied and the results were compared to ordinary ingredients, namely gibberellic acid (GA3) and KNO3. The extraction of parameters was carried out using four-parameter Hill function. The results reveal that HCN may significantly improve critical parameters involved in pistachio seed germination. In Shahpasand variety, seeds treated with HCN germinated prior to other treatments (150.53 hours after treatment) and achieved 50% germination earlier than other treatments (199.00 hours only). According to the results, utilization of HCN in seed testing experiments may be encouraged.

Control of clubroot (Plasmodiophora brassicae) in oilseed rape using varietal resistance and soil amendments

Clubroot is a major threat to global brassica production. It has been an increasing problem in UK oilseed rape (OSR) crops due to the persistence of the soil-borne pathogen responsible for disease, Plasmodiophora brassicae, exacerbated by close rotations. Field surveys in the UK in the years 2007–2010 showed that clubroot was present in all areas of the UK where OSR was grown with 52% of the selected sites testing positive. Varietal resistance and soil amendment with calcium carbonate, calcium cyanamide and boron alone or in various combinations applied before sowing were assessed for the potential to manage clubroot. Soil amendments gave variable control between sites and years but showed some potential as part of a clubroot management strategy. Varietal resistance remained the more effective management option providing 50–95% disease control at three sites in England. However, this control was not consistently effective at sites in Scotland where resistant OSR varieties have been heavily used in rotations. Yield losses were demonstrated at 0.03tha−1 for every 1% increase in clubroot severity in the susceptible variety Kommando. Yield losses were only slightly lower per 1% increase in clubroot severity for the resistant variety Mendel at 0.028tha−1 despite lower disease levels. Losses in affected crops can therefore equate to over 50% of potential yield in severely infected crops. Soil testing for clubroot and lengthening rotations are important to the long term management of clubroot as varietal resistance and soil amendments can reduce clubroot severity but provide inconsistent results.

Back Cover: Iridium-Catalyzed [2+2+2] Cycloaddition of α,ω-Diynes with Cyanamides (Adv. Synth. Catal. 18/2015)

Back Cover: Iridium-Catalyzed [2+2+2] Cycloaddition of α,ω-Diynes with Cyanamides (Adv. Synth. Catal. 18/2015)

Suppression on plant-parasitic nematodes using a soil fumigation strategy based on ammonium bicarbonate and its effects on the nematode community.

Banana production is severely hindered by plant-parasitic nematodes in acidic, sandy soil. This study investigated the possibility of applying a novel fumigation agent based on ammonium bicarbonate as a strategy for controlling plant-parasitic nematodes under sealed conditions. Moreover, its effects on the nematode community in pot and field experiments were also measured using morphology and feeding-habit based classification and the PCR-DGGE method. Results showed that a mixture (LAB) of lime (L) and ammonium bicarbonate (AB) in suitable additive amounts (0.857 g kg−1 of L and 0.428 g kg−1 of AB) showed stronger nematicidal ability than did the use of AB alone or the use of ammonium hydroxide (AH) and calcium cyanamide (CC) with an equal nitrogen amount. The nematode community was altered by the different fumigants, and LAB showed an excellent plant-parasitic nematicidal ability, especially for Meloidogyne and Rotylenchulus, as revealed by morphology and feeding-habit based classification, and for Meloidogyne, as revealed by the PCR-DGGE method. Fungivores and omnivore-predators were more sensitive to the direct effects of the chemicals than bacterivores. This study explored a novel fumigation agent for controlling plant-parasitic nematodes based on LAB and provides a potential strategy to ensure the worldwide development of the banana industry.

Relationship between endodormancy, FLOWERING LOCUS T and cell cycle genes in Vitis vinifera.

In grapevines, the increased expression of VvFT , genes involved in the photoperiodic control of seasonal growth ( VvAP1, VvAIL2 ) and cell cycle genes ( VvCDKA, VvCDKB2, VvCYCA1, VvCYCB, VvCYCD3.2 ) in the shoot apex relative to the latent bud, suggests a high mitotic activity of the apex which could prevent them to enter into endodormancy. Additionally, the up-regulation of these genes by the dormancy-breaking compound hydrogen cyanamide (H 2 CN 2 ) strongly suggests that VvFT plays a key role in regulating transcriptionally cell cycle genes. At the end of the growing season, short-day (SD) photoperiod induces the transition of latent grapevine buds (Vitis vinifera L) from paradormancy (PD) to endodormancy (ED), which allows them to survive the cold temperatures of winter. Meanwhile, the shoot apex gradually decreases its growth without entering into ED, and as a result of the fall of temperatures at the beginning of autumn, dies. To understand developmental differences and contrasting responses to environmental cues between both organs, the expression of cell cycle genes, and of genes involved in photoperiodic control of seasonal growth in trees, such as FLOWERING LOCUS T (FT), APETALA1 (AP1) and AINTEGUMENTA-like (AIL) was analyzed at the shoot apex and latent buds of vines during the transition from PD to ED. After shift to SD photoperiod, increased expression of cell cycle genes in the shoot apex suggests a high mitotic activity in this organ which could prevent them from entering into ED. Additionally, the increased expression of VvFT, VvAP1and VvAIL2 in the shoot apex, and the up-regulation of VvFT, VvAP1and cell cycle genes VvCDKA, VvCDKB2, VvCYCA.1, by the dormancy-breaking compound hydrogen cyanamide (H2CN2), strongly suggests that VvFT plays a key role in regulating transcriptionally cell cycle genes, giving thus, more support to the model for photoperiodic control of seasonal growth in trees. Furthermore, downregulation of VvFT by the SD photoperiod detected in leaves and buds of grapevines highlights the importance of VvFT in the induction of growth cessation and in ED development, probably by regulating the expression of cell cycle genes.

Facile fabrication of novel SiO2/g-C3N4 core–shell nanosphere photocatalysts with enhanced visible light activity

Novel SiO2/g-C3N4 core–shell nanospheres were simply synthesized using heating method to anneal the mixture of silica dioxide nanospheres and molten cyanamide (CA) in nitrogen atmosphere. The effects of various initial mass ratios of SiO2 nanospheres and CA molecules on the catalyst structure, surface property and catalytic activity have been systematically investigated. The characterization results show that the as-obtained photocatalysts possess the ordered core–shell nanostructure, large mesoporous distribution and inflated BET specific surface areas. The photocatalytic activities of the SiO2/g-C3N4 composites were evaluated by decomposing the rhodamine B (RhB) dye under visible light irradiation. Compared with pure g-C3N4, all of the SiO2/g-C3N4 core–shell composites showed the improved photoactivity, and the optimal SiO2/g-C3N4 catalyst (SC-3) showed the highest activity with an RhB conversion of 94.3% after 150min visible light irradiation, which is 3.5 times higher than that of pure g-C3N4. Meanwhile, the recycling test showed that the SC-3 sample owns outstanding stability and durability. The enhancement in both activity and stability can be assigned to the specific core–shell structure, inflated surface area, higher visible light adsorption and efficient charge separation originating from the closely contacted interfaces between SiO2 nanospheres and g-C3N4.

EXPLORING ALTERNATIVE BUD BREAK ENHANCING PRODUCT IN 'HAYWARD' AND 'ZESY002' (GOLD3) BY PAINTING APPLICATION

Zespri International Limited has supported the research of alternative bud-break enhancers to hydrogen cyanamide (HC), given the potential for this chemical to be de-registered for use in the kiwifruit industry and the serious risks of production loss from current kiwifruit cultivars should this occur. The bud break and flowering patterns of kiwifruit cultivars ‘Zesy002’ (Gold3) and ‘Hayward’ were studied when treated with HC and alternative bud break enhancer Bluprins® (BP), through painting at five different application dates before natural bud break (DBNB) during 2013 winter. The 2013 winter chill for the area was 279 h below 7°C compared to the 18 year average of 394 h, and this mild winter chilling condition challenge the effectiveness of the treatments studied. This investigation indicated that Gold3 shows more difficulties maintaining productivity after mild winters with an alternative bud break enhancer. ‘Hayward’ would have serious problems to find an economically sustainable bud break enhancer after a mild winter.

BUD ORIENTATION ON HORIZONTALLY TRAINED CANES MODIFIES BUDBREAK AND SHOOT FRUITFULNESS OF ACTINIDIA DELICIOSA 'HAYWARD' VINES

Consistent spring budbreak is an important aspect of regular annual cropping in kiwifruit. In regions with insufficient winter chilling, hydrogen cyanamide is commonly applied to promote even and high budbreak; however, use of this chemical is being phased out around the world because of toxicity concerns. In the absence of hydrogen cyanamide, understanding the factors influencing budbreak and the development of individual shoots is central to creating pruning systems that optimise productivity. To elucidate the effect of bud orientation on budbreak and floral shoot production in ‘Hayward’ kiwifruit, buds were selectively excised from canes based on their orientation (top, side, or bottom), and the behaviour of the remaining buds was compared with that of buds on unmodified control canes. The orientation of buds influenced the percentage budbreak of canes. Buds with a downward orientation had lower budbreak and broke later than those with an upward orientation. When upward-orientated buds were removed, percentage budbreak of downward-orientated buds increased, and they began budbreak earlier. The number of inflorescences per shoot was also altered by bud orientation. Shoots that developed from more upward orientations had greater numbers of inflorescences than shoots that developed from downward-orientated buds. With regard to budbreak and the production of floral shoots, a hierarchy of bud orientation appears to exist within a cane, from top to side to bottom.

Timing of hydrogen cyanamide application to grapevine buds

One major factor limiting the application of hydrogen cyanamide (H 2 CN 2 ) is the difficulty in deciding when to apply, since mistiming may lead to bud and crop damage. Since an effective method for monitoring the developmental stage of dormant buds is not yet available, minimizing such a risk involves the regional evaluation of application timing. For three successive years, several H 2 CN 2 application dates were evaluated in cv. Perlette vineyards in the Jordan valley in Israel. The level and uniformity of bud break did not differ significantly among the application dates tested. However, major effects of the application date on cluster number, cluster size and yield were found. The sensitivity of the reproductive meristem to H 2 CN 2 is discussed.

Combining Nitrogen Precursors in Synthesis of Non-Precious Metal ORR Catalysts with Improved Fuel Cell Performance

Platinum and platinum-alloy oxygen reduction reaction (ORR) catalysts have been implemented in the prototype, and by now also in commercial fuel cell power systems for automotive applications, successfully meeting the demanding conditions of relatively low temperature (80°C) and high acidity operating conditions of the polymer electrolyte fuel cell (PEFC). However, due to the high price of Pt, the catalyst cost is projected to account for as much as a half of the total PEFC stack cost.1 In this context, the potential replacement of Pt-based catalysts, especially in the fuel cell cathode, with non-precious metal catalysts (NPMCs) is expected to significantly reduce PEFC stack cost. Achieving such a cost benefit is, however, contingent upon reaching sufficient activity and durability with NPMC for the ORR, a requirement that the electrocatalysis research community has been striving to meet. In this presentation, we expand upon the idea of combining nitrogen precursors during NPMC synthesis to improve the performance and performance durability of non-precious metal ORR catalysts. Previously, we introduced a new non-precious metal ORR catalyst derived from two nitrogen precursors with different decomposition temperatures: easily decomposing cyanamide (CM) and more thermally stable polyaniline (PANI).2 In this approach, CM acts as an efficient pore-forming agent that allows for the formation of a highly porous structure, which in particular benefits the high-current response of the resulting electrocatalyst. Compared to the alternative approach utilizing metal-organic frameworks (MOFs),3,4 the use of cyanamide promises a very significant reduction in the NPMC cost, without sacrificing ORR activity. In an effort to further improve the PEFC performance of the two nitrogen-precursor NPMCs, we have explored approaches involving the use of ammonia treatment, the addition of various carbon supports, and inclusion of multiple transition metals. In this presentation, we will summarize the results of these studies, which have involved the extensive use of characterization techniques, such as X-ray photoelectron spectroscopy, scanning electron microscopy, scanning transmission electron microscopy, X-ray diffraction, surface area/pore distribution measurements, and nano-scale X-ray computed tomography. In the conclusion, we will also define critical factors for enhancing the performance of NPMCs in the PEFC cathode and outline directions for future research. Acknowledgement Financial support for this research by DOE-EERE through Fuel Cell Technologies Office is gratefully acknowledged. Microscopy research supported through a user project at ORNL’s Center for Nanomaterials Sciences, which is an Office of Science User Facility. References Spendelow et al., DOE Fuel Cell Technologies Office, Fuel Cell System Cost-2013, (2013).Hoon T. Chung et al., “Combined nitrogen precursor approach to develop highly active non-precious metal oxygen reduction reaction catalyst.” in preparation.S. Ma et al., “Cobalt Imidazolate Framework as Precursor for Oxygen Reduction Reaction Electrocatalysts,” Chem. Eur. J. 17, 2063 (2011).Proietti et al., “Iron-based cathode catalyst with enhanced power density in polymer electrolyte membrane fuel cells,” Nat. Commun. 2, 416 (2011)

Hydrogen Cyanamide Induced Cutaneous Reactions: Occupational Pesticide Poisoning and Need for Surveillance

Pesticides are used widely throughout the world and is one of major cause of occupational, accidental and intentional poisoning with an estimated 3 million cases annually with reported 2,20,000 deaths worldwide. On an average 3% of agricultural workers in developing countries suffer an episode of pesticide poisoning per year. An 18 year old male patient with cutaneous reactions admitted to the medicine ward revealed to the exposure and use of pesticide (Dormex) in the agricultural field. The poison was investigated for the observed cuteneous reaction and the detailed poison information was provided. The patient was diagnosis with irritant contact dermatitis with secondary infection due to exposure to Dormex. The patient was effectively treated with corticosteroids and antihistamines. Dormex is a plant growth regulator with Hydrogen Cyanamide as an active ingredient. Hydrogen cyanamide is known to cause severe cutaneous reactions such as erythema multiform (EM), Stevens Johnsons Syndrome (SJS), Toxic Epidermal Necrolysis (TEN). Lack of awareness of its adverse effects and improper handling pose the risk of toxicity which can be prevented by taking appropriate precautionary measures against the exposure.

Combined Nitrogen Precursor Approach to Develop Cobalt-Based Non-Precious Catalysts for Polymer Electrolyte Fuel Cell Cathodes

The cost of the platinum-based catalysts used in polymer electrolyte membrane fuel cells (PEFCs) is estimated to be almost half of the overall fuel cell stack cost under projected conditions of fuel cell vehicle mass production [1]. To reduce this economic constraint, the development of non-platinum group metal (non-PGM) cathode catalysts with high oxygen reduction reaction (ORR) activity is highly desirable. Our group and others have demonstrated immense progress in non-PGM catalyst development, with the specific class of pyrolyzed transition metal-nitrogen-carbon (M-N-C) catalysts achieving high activity [2,3]. In order to realize the successful implementation of these non-PGM catalysts into PEFC systems, the significant issue of operational durability must be addressed. The two most promising M-N-C catalyst technologies are based on either iron or cobalt, with the former conventionally providing enhanced ORR performance, approaching that of commercial platinum catalysts. From a system perspective, however, the presence of iron species in the catalyst layer is highly undesirable. This is owing to the well-known Fenton chemistry, resulting in the formation of highly reactive free-radical species that in turn leads to membrane and/or ionomer decomposition. To address this challenge, we prepared cobalt-based catalysts using the combined-precursor approach recently developed at Los Alamos National Laboratory [4]. This approach utilizes both polyacrylonitrile (PANI) and cyanamide (CM) as nitrogen/carbon precursors that are combined and pyrolyzed with a carbon support and cobalt salt. Individually, both PANI and CM precursors have been previously demonstrated capable of forming highly ORR-active catalysts. Through this approach, we found that the relatively low decomposition temperature (ca. 260°C) of CM allows it to synergistically act as a pore-forming agent and yield high surface-area catalysts. This in turn leads to excellent H2-air fuel cell performance due to the reduced mass transport limitations in the cathode. In this work, Co-CM-PANI-C was formed and found to provide promising activity towards the ORR in acidic electrolyte. Particularly, it was determined that 8.0 wt.% cobalt in the precursor mixture provided optimal ORR activity through half-cell investigation (Figure 1). A half-wave potential of ca. 0.74 V vs.RHE was achieved, with current investigations underway to understand and optimize the structure-performance-durability relationships. These results, along with performance and durability data from both half-cell and MEA evaluation, will be presented at the meeting. Acknowledgements Financial support for this was has been provided by the DOE-EERE through the Fuel Cells Technologies Office and by the Natural Sciences and Engineering Research Council of Canada (NSERC).

An Approach for Highly Porous Non-Precious Metal Catalyst Synthesis for Polymer Electrolyte Fuel Cell Cathodes

Polymer electrolyte fuel cells (PEFCs) are electrochemical devices that convert chemical energy into electricity for a variety of applications, the most notable of which is transportation. The integration of PEFCs at scale for transportation applications however has been hindered due to the high price of platinum (Pt) that is the state-of-the-art catalyst for the oxygen reduction reaction (ORR) on the cathode. Replacing Pt with non-precious metal catalysts (NPMCs) synthesized from earth abundant elements (C, N, Fe, etc.) is therefore essential to deploy PEFCs for transportation applications. Recently, many advances have been realized towards the development of NPMCs. One of the most important advances is the synthesis of highly porous (HP)-NPMCs. HP-NPMCs allow for improved active site accessibility as well as facilitated mass transport. This is especially important as the relatively low volumetric activity of NPMCs leads to a significantly larger electrode thickness for NPMCs in comparison to Pt/C catalysts, i.e., ca. 70 μm vs. 10 μm, respectively. Two main strategies that have been employed to achieve HP-NPMCs are the use of: (i) metal-organic frameworks (MOFs) [1] and (ii) template agents such as silica [2]. MOFs however are generally very expensive, with only very few commercially available, and a silica template approach requires using highly corrosive and hazardous reagents such as hydrofluoric acid for a silica template removal. These approaches are therefore far from ideal for efficient catalyst production. In this work, we adopted a more proficient technique that uses combined nitrogen precursors. With this method, a lower decomposition temperature nitrogen precursor, cyanamide (CM), and higher decomposition temperature nitrogen precursor, polyanniline (PANI), are concurrently used. Under this circumstance, during heat-treatment, CM works as an efficient foaming agent. Indeed, we can synthesize HP-NPMCs with a microporous surface area of 1585 m2/g, and demonstrate record H2-air fuel cell performance (Fig. 1). In this talk, more detailed microscopic features and electrochemical and fuel cell performances of these HP-MPMCs will be presented. Acknowledgements Financial support for this has been provided by the DOE-EERE through the Fuel Cells Technologies Office. References Proietti et al., Nat. Commun. 2, 416 (2011).Serov et al., Appl. Catal. B: Environmental, 127, 300 (2012). Figure 1

Enhanced Oxygen Reduction Activity of N-Doped Multiwalled Carbon Nanotubes in Alkaline Media

A great deal of work has been made to develop new electrocatalysts for oxygen reduction reaction (ORR) in acid and alkaline media. In order to replace expensive and scarce Pt-based catalysts that have been primarily employed as cathode catalysts in low-temperature fuel cells, different carbon-based materials that possess lower price, better availability and improved chemical stability have been studied. Nitrogen-doped nanocarbons can be used as alternatives to Pt-based cathode catalysts. Previously, we have investigated the reduction of O2 on CVD grown nitrogen-doped carbon nanotubes,1 on CNTs heat-treated in the presence of urea2 and on N-doped graphene3 and few-layer graphene/multiwalled carbon nanotube (FLG/MWCNT) composites.4 In this work the electrocatalysis of oxygen reduction on nitrogen-doped carbon nanotube (NCNT) catalysts has been investigated. These NCNT materials were prepared from two different nitrogen precursors and acid-treated MWCNTs. Cyanamide (CM) and dicyandiamide (DCDA) were used as nitrogen precursors and the doping was achieved by pyrolysing MWCNTs in the presence of these nitrogen-containing compounds at 800 °C. The MWCNT-to-nitrogen precursor mass ratio was 1:20. The N-doped carbon nanotube catalyst samples were characterized by scanning electron microscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy, the latter method revealed successful nitrogen doping. The electrocatalysis of the ORR was studied in 0.1 M KOH on glassy carbon (GC) electrodes modified with N-doped CNT electrocatalysts employing the rotating disk electrode (RDE) method. The NCNT-DCDA material showed a better ORR performance than the NCNT-CM catalyst. Fig. 1 presents the ORR polarization curves on NCNT-DCDA at various rotation rates and Fig. 2 shows the Koutecky-Levich plots for this catalyst. As can be seen, the number of electrons transferred (n) is close to 4, which is advantageous from the point of view of fuel cell application. A comparison of the RDE results indicated that these metal-free NCNT catalysts possess remarkable electrocatalytic activity toward the ORR in alkaline media similar to that of commercial Pt/C catalyst (Fig. 3). The results obtained in this work are important for the development of Pt-free cathode catalysts for alkaline membrane fuel cells (AMFC). In the next stage of work these materials will be tested in AMFC conditions.

Nitrogen‐Doped Multilayer Graphene as Functional Filler for Carbon/Polyamide 12 Nanocomposites

Herein, we report on the facile thermolysis process for producing nitrogen‐doped few‐layer graphene (CN) as a functional filler derived from graphite oxide (GO) and cyanamide (CA). The nitrogen content is governed by the thermolysis temperature and CA content. As compared to conventional thermally reduced GO, the nitrogen doping by GO/CA thermolysis at 800 °C accounts for a substantial increase of electrical filler conductivity from 48 to 467 S · cm−1. According to XPS measurements, pyridinic, pyrrolic, and graphitic nitrogen groups were incorporated into graphene during thermolysis. Graphene/polyamide 12 (PA12) composites containing between 1 and 5 wt% were prepared by melt compounding. At 5 wt% graphene filler content, the Young's modulus was increased by +53% with respect to PA12. Whereas nitrogen doping did not affect mechanical properties of graphene/PA12, it greatly improved the electrical conductivity of both graphene and the corresponding graphene/PA12 nanocomposites. Hence, the nitrogen doping of graphene holds a great promise for improving the performance of functional graphene fillers.

Dormancy Breaking of the Fig Tree with Hydrogen Cyanamide and Garlic Extrate

Dormancy Breaking of the Fig Tree with Hydrogen Cyanamide and Garlic Extrate

Abscisic acid (ABA) regulates grape bud dormancy, and dormancy release stimuli may act through modification of ABA metabolism.

In warm-winter regions, induction of dormancy release by hydrogen cyanamide (HC) is mandatory for commercial table grape production. Induction of respiratory stress by HC leads to dormancy release via an uncharacterized biochemical cascade that could reveal the mechanism underlying this phenomenon. Previous studies proposed a central role for abscisic acid (ABA) in the repression of bud meristem activity, and suggested its removal as a critical step in the HC-induced cascade. In the current study, support for these assumptions was sought. The data show that ABA indeed inhibits dormancy release in grape (Vitis vinifera) buds and attenuates the advancing effect of HC. However, HC-dependent recovery was detected, and was affected by dormancy status. HC reduced VvXERICO and VvNCED transcript levels and induced levels of VvABA8'OH homologues. Regulation of these central players in ABA metabolism correlated with decreased ABA and increased ABA catabolite levels in HC-treated buds. Interestingly, an inhibitor of ethylene signalling attenuated these effects of HC on ABA metabolism. HC also modulated the expression of ABA signalling regulators, in a manner that supports a decreased ABA level and response. Taken together, the data support HC-induced removal of ABA-mediated repression via regulation of ABA metabolism and signalling. Expression profiling during the natural dormancy cycle revealed that at maximal dormancy, the HC-regulated VvNCED1 transcript level starts to drop. In parallel, levels of VvA8H-CYP707A4 transcript and ABA catabolites increase sharply. This may provide initial support for the involvement of ABA metabolism also in the execution of natural dormancy.

Zinc(ii)-mediated generation of 5-amino substituted 2,3-dihydro-1,2,4-oxadiazoles and their further ZnII-catalyzed and O2-involving transformations

ZnII-activated cyanamides NCNR2 react with the acyclic N-alkyl ketonitrones Ph2CN+(O−)R′ achieving uncomplexed 2,3-dihydro-1,2,4-oxadiazoles.