Period Of Nitrogen Research Articles

Induction of nitrate uptake in Sauvignon Blanc and Chardonnay grapevines depends on the scion and is affected by the rootstock

Background and Aims Nitrate is a major form of inorganic nitrogen present in cultivated soils; however, information on the mechanisms responsible for uptake of the anion in grapevines is scarce. Methods and Results The response to external nitrate was studied in two clones of the cultivars Chardonnay and Sauvignon Blanc. Grapevines, own-rooted or grafted on the two rootstocks SO4 and K5BB, were grown in nutrient solution and, after a period of nitrogen (N)-deprivation, exposed to 0.2 or 1 mmol/L nitrate. The uptake was an inducible process, operated by high- and low-affinity transport systems. The magnitude and time dependence of the induction varied as a function of the clone. Uptake rate as a function of nitrate external concentration showed a multiphasic pattern. Although nitrate exposure caused a transient up-regulation of nitrate influx transporter genes, a clear correlation with the rise in nitrate uptake could not be found; in contrast, a negative relationship between changes in uptake rates and expression of a nitrate efflux transporter gene was observed. Conclusions In the grapevine, the response of low- and high-affinity transport systems to external nitrate was favoured by the presence of the rootstock and also dependent on the characteristics of the scion. Low-affinity uptake and efflux from root cells conceivably play an important role in the overall N-nitrate acquisition. Significance of the Study This study shows that activation of mechanisms involved in nitrate uptake in the grapevine is strongly affected by the scion–rootstock combination. Results may be significant for developing agronomic practices and selection programmes related to nitrogen use in the grapevine.

Investigation of Different Mn–Fe Oxides as Oxygen Carrier for Chemical-Looping with Oxygen Uncoupling (CLOU)

The appropriate oxygen carrier for chemical-looping with oxygen uncoupling (CLOU) should be thermodynamically capable of being oxidized in the air reactor and also release gaseous O2 in the fuel reactor at appropriate temperatures and oxygen partial pressures. It should also be mechanically durable, cheap, and environmentally friendly. Iron–manganese oxides appear to be especially promising due to favorable thermodynamics. In this work, combined metal oxides of iron and manganese were investigated for the CLOU process. Particles with different ratios of Mn/Fe were produced using spray drying. The particles were calcined at 950 and 1100 °C for 4 h and then tested with respect to parameters important for CLOU. The crushing strength for these materials was between 0.1 to 1.7 N, depending on their composition and sintering temperature. The ability of the iron–manganese oxide particles to release oxygen in the gas phase was examined by decomposition of the material in a stream of N2. Moreover, the reaction with both methane and synthesis gas (50/50% CO/H2) was examined in a batch fluidized bed reactor. Here, the particles were alternately oxidized with 5% O2 and reduced in N2 or with fuel at 850 °C, 900 and 950 °C. From the results, it can be concluded that during the nitrogen period, the oxygen carriers with Mn3O4 content in the range from 20 wt % to 40 wt % release oxygen at 900 °C, whereas the materials with higher manganese content show no oxygen release. This is because they could not be oxidized to bixbyite. By decreasing the temperature from 900 to 850 °C, it was possible to oxidize oxygen carriers with manganese oxide content of 50 wt % and higher, and consequently, oxygen release during the nitrogen period was seen for these materials. This is in agreement with the phase diagram for this system. The reaction rate with methane follows the oxygen release trend very well. At the higher reaction temperature, 950 °C, oxygen carriers with manganese content in the range from 25% to 33% show the best gas conversion of methane. At 850 °C, on the other hand, high methane conversion is seen for particles with high manganese content. In fact, several particles had almost full conversion of methane to CO2 and H2O at 850 °C using a bed mass in the batch reactor corresponding to 70 kg oxygen carrier/MW.

Memory curves used in establishing the time variation of metastable concentrations in the afterglow period in nitrogen and neon

The expression 'memory curve' is used for functions showing the dependences of breakdown time delays td on the afterglow period tau at various other preset experimental parameters. The time delay values are averages of series of more than 100 measurement cycles each of the electrical breakdown time delays in nitrogen and neon filled diodes at 40 mbar for various preset tau values. It was established that the slopes of curves of td against tau , the memory curves, do not depend on the voltage applied to the diode within the range of 15% to 25% above the static breakdown voltage, indicating that these slopes measure the time variation of metastable concentrations C within the diode, i.e. dC/d tau , in the afterglow period.

ChemInform Abstract: STUDIES OF NITRILES. VII. SYNTHESIS AND PROPERTIES OF 2‐AMINO‐3,3‐DICHLOROACRYLONITRILE (ADAN)

AbstractDichlor‐phenyl‐acetonitril (I) liefert mit Blausäure das Addukt (II), das mit Zink in wäßrigem Äthanol zu (III) und in Essigsäureanhydrid/Essigsäure zu einem Gemisch aus (IV) und (V) reduziert wird.

Studies of nitriles. VII. Synthesis and properties of 2-amino-3,3-dichloroacrylonitrile (ADAN).

2-Amino-3, 3-dichloroacrylonitrile (ADAN), a versatile polyfunctional synthetic intermediate, was prepared in 96% yield by addition of HCN to the C-N triple bond of dichloroacetonitrile (11a). The structural proof for ADAN, an enamino nitrile, comes from comparison of the spectral data with those of 2-imino-3, 3, 3-trichloropropionitrile (15), a model compound for α-imino nitrile. Similarly, 2-amino-3, 3-dibromoacrylonitrile (13) was prepared from dibromoacetonitrile (11b) and HCN in 82% yield. ADAN, although relatively unstable in air at room temperature, can be stored without detectable change for a long period in nitrogen or ether vapor atmosphere at low temperatures. 2-Amino-3, 3-bis (substituted mercapto) acrylonitriles (18a-c), mercapto-analogues of ADAN, were prepared from ADAN or its N-acyl derivatives (16, 19) by nucleophilic substitution of the chlorine atoms with mercaptides, and in the latter case, with subsequent hydrolysis of the N-acyl group. Hydrolysis of the cyano group of N-acyl derivatives (16, 21, 22) gave the corresponding carboxamides (23), carboxylic acids (24), and N-t-butylcarboxamides (26) in good yields.

Respiratory Metabolism in Detached Rhododendron Leaves

Some of the measurements described below were first made many years ago (21; see 26, 27, 28) as part of an investigation of the occurrence of the Pasteur effect in plant organs. More recently, with the development of interest in factors controlling respiratory metabolism, our attention was redirected to 2 of the plant materials originally studied, namely rhododendron leaves for which there was evidence of a marked Pasteur effect and young seedlings of buckwheat, the one material used for which no evidence of a Pasteur effect emerged. This paper describes 1 part of this work and is restricted to restilts obtained with detached whole leaves of rhododendron. Many investigations made for convenience with leaf discs or slices will be described elsewhere later, for their relevance to metabolism in the intact leaf is still in some doubt. The experiments described here are largely concerned with production and consumption of metabolites in the leaves in air, in pure nitrogen, and on return to air after a period in nitrogen. Particular attention has been directed toward transitory changes in concentrations of glycolytic intermediates and keto-acids as guides to changes of rates of glycolysis and of oxidative reactions of the tricarboxylic acid cycle. These data have the limitation of all such measurements in that they represent average concentrations for whole cells which may bear little relation to changes in specific metabolic pools associated with glycolysis and cycle oxidations but are nevertheless a necessary preliminary to further work. Also, because of renewed interest elsewhere in the origin of the anaerobic CO, output (24) and of the possible consumption of ethanol (9, 10, 29), some attention is given here to these aspects of metabolism.

Effects of red and far-red light on the fluorescence yield of chlorophyll in vivo

The fluorescence of chlorophyll a and C-705 in green leaves has been investigated during the induction period of photosynthesis in air and in nitrogen. A brief illumination of a leaf with red light causes an increased yield of chlorophyll a fluorescence which persists for a longer period in nitrogen than air. The increased fluorescence yield, produced by red light, can be inhibited by a subsequent irradiation with far-red light. The action spectrum for the effect of far-red light shows a maximum near 705 mμ. The effects of red and far-red light on the fluorescence yield of chlorophyll a are thought to be another manifestation of the second Emerson effect.

The Effects of Decapitation, Lack of Oxygen, and Low Temperature on the Endogenous 24-hour Rhythm in the Growth-rate of theAvenaColeoptile

Further work on the endogenous rhythm in the growth-rate of the Avena coleoptile was carried out by the methods previously described. Decapitation of the coleoptile does not prevent induction of the rhythm, nor does it affect the phase of a rhythm previously established. When seedlings are transferred to darkness and are simultaneously deprived of oxygen by replacing the surrounding air with nitrogen, a rhythm is induced, but the first peak is delayed for a period approximately equal to that of the nitrogen treatment. Provided the period in nitrogen is not excessively prolonged, the retardation of the second peak is less than that of the first. This suggests that the rate of the time-keeping mechanism has become accelerated. Since only a part of the initial retardation in the rhythm is thus eliminated, a change in phase persists. The younger the seedlings at the time of treatment, the smaller is this persistent change. When the nitrogen treatment is commenced some hours after the transfer to darkness, the retardation of the second peak is greater than when treatment and transfer are simultaneous. In each series the retardation increases expon entially as the length of the period in nitrogen is extended. Retardation followed by acceleration was also observed after the seedlings had been exposed to low temperature. It seems probable that induction of the rhythm involves the synchronization of independent time-keeping mechanisms already in existence, rather than the establishment of an entirely new system.

Studies in the respiratory and carbohydrate metabolism of plant tissues. III. Experimental studies of the formation of carbon dioxide and of the changes in lactic acid and other products in potato tubers in air following anaerobic conditions.

This paper is the third in a series dealing with the anaerobic metabolism of potato tubers. In the two earlier papers (Barker & Saifi 1952 a, b ) we considered the changes which occurred during exclusion of oxygen, in the rate of CO 2 production and in the contents o sugar, lactic acid, alcohol and of an unidentified alcohol-soluble fraction. This paper is concerned with the influence of air following a period of anaerobiosis. The data given in the present paper showed that on transfer from the anaerobic to the aerobic state there was an increase in the rate of CO 2 production above the normal aerobic level, followed by a fall towards this level. Associated with this so-called after-effect there was a rapid disappearance of the lactic acid which had accumulated during the period in nitrogen and a quick increase in the sugar content, followed by a slower decrease. These experimental results are analyzed in the fourth paper in the series (page 522).