Plant maintenance and environmental stress. Summarising the effects of contrasting elevation,soil, and latitude on Quercus ilex respiration rates

Aims

Rice (Oryza sativa L.), wheat (Triticum aestivum L.) and common bean (Phaseolus vulgaris L.) are major staple food crops consumed worldwide. Zinc (Zn) deficiency represents a common micronutrient deficiency in human populations, especially in regions of the world where staple food crops are the main source of daily calorie intake. Foliar application of Zn fertilizer has been shown to be effective for enriching food crop grains with Zn to desirable amounts for human nutrition. For promoting adoption of this practice by growers, it is important to know whether foliar Zn fertilizers can be applied along with pesticides to wheat, rice and also common bean grown across different soil and environmental conditions.

Methods

The feasibility of foliar application of zinc sulphate (ZnSO₄.7H₂O) to wheat, rice and common bean in combination with commonly used five fungicides and nine insecticides was investigated under field conditions at the 31 sites-years of seven countries, i.e., China, India, Pakistan, Thailand, Turkey, Brazil and Zambia.

Results

Significant increases in grain yields were observed with foliar Zn/foliar Zn?+?pesticide (5.2–7.7 % of wheat and 1.6–4.2 % of rice) over yields with no Zn treatment. In wheat, as average of all experiments, higher grain Zn concentrations were recorded with foliar Zn alone (41.2 mg kg^?1) and foliar Zn?+?pesticide (38.4 mg kg^?1) as compared to no Zn treatment (28.0 mg kg^?1). Though the magnitude of grain Zn enrichment was lesser in rice than wheat, grain Zn concentrations in brown rice were significantly higher with foliar Zn (24.1 mg kg^?1) and foliar Zn?+?pesticide (23.6 mg kg^?1) than with no Zn (19.1 mg kg^?1). In case of common bean, grain Zn concentration increased from 68 to 78 mg kg^?1 with foliar Zn alone and to 77 mg kg^?1 with foliar Zn applied in combination with pesticides. Thus, grain Zn enrichment with foliar Zn, without or with pesticides, was almost similar in all the tested crops.

Conclusions

The results obtained at the 31 experimental site-years of seven countries revealed that foliar Zn fertilization can be realized in combination with commonly-applied pesticides to contribute Zn biofortification of grains in wheat, rice and common bean. This agronomic approach represents a useful practice for the farmers to alleviate Zn deficiency problem in human populations.

     

Phytoremediative potential of salt-tolerant grass species for cadmium and lead under contaminated nutrient solution

Abstract

Phytoremediation of heavy metal contaminated soils represents a promising technique and salt-tolerant hyperaccumulators for multiple metals are the need of time. Therefore, phytoremediation potential of four salt-tolerant grass species [Dhab (Desmostachya bipinnata), Kallar (Leptochloa fusca), Para (Brachiaria mutica) and Sporobolus (Sporobolus arabicus Boiss)] was evaluated for cadmium (Cd) and lead (Pb) in a hydroponic study. The plants were harvested after a growth period of 3 months in a nutrient solution containing different levels of Cd (0, 5, and 25?mg?L^?1) and Pb (0, 25, and 125?mg L^?1). Results indicated that Dhab grass showed the highest root and shoot dry matter yield followed by Para, Kallar and Sporobolus grass irrespective of metal or its level under which they were grown. All the grass species showed considerable Cd-accumulating potential with an accumulation of >150?mg kg^?1of shoot dry matter at a higher level of Cd-contamination (25?mg?L^?1). While in case of shoot Pb-accumulation only Para grass performed well and accumulated Pb >1000?mg kg^?1 of shoot dry matter at the higher level of Pb-contamination (125?mg?L^?1). Moreover, Para and Dhab grasses performed better for shoot Cd-uptake, while only Para grass showed promising shoot Pb uptake potential. In conclusion, these grass species could be penitentially used for phytoremediation of salt-affected Cd and Pb contaminated soils.     

Effects of Cadmium,Copper, Lead,and Zinc Contamination on Metal Accumulation by Safflower and Wheat

Accumulation of heavy metals (HMs) in cultivated soils is a continuing environmental problem in many parts of the world. An increase in HM concentration can enhance uptake of toxic metals by crops and enter the human food chain. In this study, the uptake behavior of wheat and safflower was evaluated in a calcareous soil by using 12 undisturbed columns in which half were artificially contaminated. Heavy metals in the form of CdCl₂ (15 mg Cd kg^{? 1}), CuSO₄ (585 mg Cu kg^{? 1}), Pb(NO₃)₂ (117 mg Pb kg^{? 1}), and ZnCl₂ (1094 mg Zn kg^{? 1}) were sprayed on the soil surface and completely mixed in the top 10 cm. The background total concentrations of Cd, Cu, Pb and Zn were 1.6, 29.5, 17.5 and 61.2 mg kg^{? 1}, respectively. After metal application, half of the columns (3 contaminated and 3 uncontaminated) were sown with wheat (Triticum aestivum) and the other half with safflower (Carthamus tinctorious) and grown for 74 days until maturity. After harvesting, soil columns were cut into 10-cm sections and analyzed for HNO₃- and DTPA-extractable metal concentrations. Metal concentrations were also measured in different plant tissues. The results showed that artificial contamination of topsoil decreased the transpiration rate of wheat by 12% and that of safflower by 6%. In contaminated columns, Cd, Cu, Pb, and Zn accumulation in wheat shoot was greater by 8.0-, 1.9-, 3.0-, and 2.1-fold than the control, respectively. Accordingly, these numbers were 46.0-, 1.3-, 1.7-, and 1.6-fold in safflower shoot. Soil contamination with HMs resulted in a 55% decrease in shoot dry matter yield of wheat while it had no significant effect on shoot dry matter of safflower. The normalized water consumption for safflower was therefore not affected by metal contamination (≈ 13 mm H₂O g^{? 1} of dry weight for all safflower and uncontaminated wheat treatments), while contaminated wheat was much less water efficient at about 27 mm H₂O g^{? 1} dry weight. It was concluded that although artificial contamination had a negative effect on wheat growth, it did not affect safflower's normal growth and water efficiency.     

Stomatal behaviour in a beech canopy: an analysis of Bowen ratio measurements compared with porometer data

On the basis of measurements or stand transpiration and microclimate, the bulk stomatal or bulk leaf conductance (g_L) of a beech forest in northern Germany was calculated for periods in which leaves were fully expanded and the canopy was dry. This conductance depends strongly on light and humidity conditions above the forest. During periods with photosynthetic photon flux densities Q > 1200 μmol m^?2s^?1, g_L was reduced from 1500mmol m^?2s^?1 at a vapour pressure deficit D= 0.5kPa to 500 mmol m^?2s^?1 at D= 2kPa. Light saturation of g_L was not reached until Q= 1200 μmol m^?2s^?1 at low D, or until even higher Q at higher D. The dependence of g_L, on Q and D was described mathematically by a non-linear equation that requires two empirical parameters. Values for g_L as simulated by this equation provided a satisfactory agreement with independent porometer data collected on single leaves and scaled up to the canopy. A comparison of stomatal and aerodynamic conductances showed a strong coupling between the forest canopy and the atmosphere, indicating that transpiration of the beech forest is controlled mainly by the stomata.     

Arbuscular mycorrhizal fungi induced changes in rhizosphere,essential oil and mineral nutrients uptake in dill/common bean intercropping system

The fundamental aim of this research was to evaluate the effects of Funneliformis mosseae on nutrient uptake and distribution in solo cropping and intercropping of common bean Phaseolus vulgaris and dill Anethum graveolens in the field, using a factorial arrangement of treatments. The factors were seven cropping systems including (a) common bean sole cropping (40 plants m^?2), (b) dill sole cropping at different densities (25, 50 and 75 plants m^?2) and (c) the additive intercropping of dill/common bean (25/40, 50/40 and 75/40 plants m^?2), with (+AM) or without (?AM) arbuscular mycorrhiza colonisation. In all cropping systems, AM colonisation improved dry weight and P, K, Fe, Zn and Mn contents of dill plants. Cultivable bacterial community was also increased in the dill/common bean intercropping. Yield of essential oil in dill shoot was improved as a result of AM colonisation and intercropping.     

Comparison of production efficiency among field crops related to nitrogen nutrition and application

It has been generally considered that the low productivity of Leguminosae is caused by accumulation in the reproductive organs of a large amount of protein and lipid, since the biochemical costs of synthesizing these compounds is higher than that for carbohydrate. However, we report here on results which show that: the growth efficiencies (dry matter accumulated/ (dry matter accumulated + respiration)) of reproductive organs of Gramineae and Leguminosae were similar; the growth efficiency of rice in the vegetative stage was greater than that of soybean and field bean, regardless of nitrogen application rate; and when ¹⁴CO₂, ¹⁴C-sucrose or ¹⁴C-asparagine were introduced to the leaf at the maturation stage, respiratory loss of the introduced ¹⁴C was greater in soybean and field bean, especially in the light, than in rice. Thus, it is assumed that the low productivity in Leguminosae is caused by a larger respiratory loss under both dark and light condition in the shoot, and not in the reproductive organs.     

Silicon accumulation and water uptake by wheat

Silicon (Si) content in cereal plants and soil-Si solubility may be used to estimate transpiration, assuming passive Si uptake. The hypothesis for passive-Si uptake by the transpiration stream was tested in wheat (Triticum aestivum cv. Stephens) grown on the irrigated Portneuf silt loam soil (Durixerollic calciorthid) near Twin Falls, Idaho. Treatments consisted of 5 levels of plant-available soil water ranging from 244 to 776 mm provided primarily by a line-source sprinkler irrigation system. Evapotranspiration was determined by the water-balance method and water uptake was calculated from evapotranspiration, shading, and duration of wet-surface soil. Water extraction occurred from the 0 to 150-cm zone in which equilibrium Si solubility (20°C) was 15 mg Si L^–1 in the A_p and B_k (0–58 cm depth) and 23 mg Si L^–1 in the B_kq (58–165 cm depth).At plant maturity, total Si uptake ranged from 10 to 32 g m^–2, above-ground dry matter from 1200 to 2100 g m^–2 and transpiration from 227 to 546 kg m^–2. Silicon uptake was correlated with transpiration (Si_up=–07+06T, r²=0.85) and dry matter yield with evapotranspiration (Y=119+303ET, r²=0.96). Actual Si uptake was 2.4 to 4.7 times that accounted for by passive uptake, supporting designation of wheat as a Si accumulator. The ratio of Si uptake to water uptake increased with soil moisture. The confirmation of active Si uptake precludes using Si uptake to estimate water use by wheat.     

Effect of Bursaphelenchus xylophilus infection on leaf photosynthetic characteristics and resource‐use efficiency of Pinus massoniana

Pine wilt disease (PWD ) is considered as the most destructive forest‐invasive alien species in China. We measured gas exchange parameters and foliar carbon isotope ratios (δ¹³C) of different infection phases of Masson pine in order to investigate the effect of Bursaphelenchus xylophilus infection on photosynthetic responses and resource‐use efficiency. The results showed that net photosynthetic rate (P _n), transpiration rate (T ), stomatal conductance (g _s), and internal CO ₂ concentrations (C _i) decreased in the infested trees at photosynthetic photon flux density (PPFD ) levels from 0 to 2,000 μmol m^?2 s^?1 compared with controls. The maximum net photosynthetic rate (P _max) was significantly declined in the infected trees than in controls (p  <  .05). There also exist significant differences in dark respiration rate (R _d) among different infection phases (p  <  .05), but the value is highest in the middle infection phase, followed by the control and then the terminal infection phase. This indicates that Pinus massoniana plants need to consume more photosynthetic products during the middle infection phase in order to defend against pine sawyer beetle feeding and PWD infection. Isotopic analysis revealed a significant decrease of the foliar δ¹³C (p  <  .05), as much as 2.5‰ lower in the infected trees. The mean leaf N content was about 12.94% less in the middle infection phase and 27.06% less in the terminal infection phase, causing a significant increase of the foliar C:N ratio in infested trees. Both of the net photosynthetic rates and foliar δ¹³C were linearly correlated with the foliar N content. We also found a significant decrease (p  <  .05) of resource‐use efficiency in PWD ‐induced P. massoniana plants, which can be attributed to the closure of stomatal pores and the inactivation or loss of both Rubisco and other key Calvin cycle enzymes. This study highlights the impact of photosynthetic characteristics, foliar carbon isotope ratios, and resource‐use efficiency of PWD ‐induced trees, which can help identify PWD infestations at the photosynthetic and physiological levels so as to better facilitate management actions.     

Enhancing Phytoremediation Potential of Pennisetum clandestinum Hochst in Cadmium-Contaminated Soil Using Smoke-Water and Smoke-Isolated Karrikinolide

The use of plant growth regulators (PGRs) and biostimulants to enhance phytoextraction is gaining popularity in phytoremediation technology. This study investigated the stimulatory effects of smoke-water (SW), a smoke-derived compound karrikinolide (KAR₁) and other known plant growth regulators (PGRs) [gibberellic acid (GA₃), kinetin (Kin) and indole-3-butyric acid (IBA)] to enhance the phytoextraction potential of Pennisetum clandestinum. Pennisetum clandestinum seedlings were grown for 10 weeks in vermiculite using Hoagland's nutrient solution and were treated with cadmium (Cd) (2, 5, and 10 mg L^?1) and SW, KAR₁ and PGRs. KAR₁ exhibited positive effects on shoot and root dry weight (140 and 137 mg respectively) at the highest concentration of Cd (10 mg L^?1) compared to all the other treatments. KAR₁ and SW treatments used in the present study significantly improved the phytoextraction potential of P. clandestinum (602 and 575 mg kg^?1 respectively) compared to the other tested PGRs. This is the first report on the use of SW and KAR₁ to enhance phytoremediation potential in P. clandestinum. Further studies are needed to elucidate the exact mechanisms of smoke constituents involved in phytoextraction potential of plant species.     

Dry deposition of ammonia gas drives species change faster than wet deposition of ammonium ions: evidence from a long‐term field manipulation

Although the effects of atmospheric nitrogen deposition on species composition are relatively well known, the roles of the different forms of nitrogen, in particular gaseous ammonia (NH₃), have not been tested in the field. Since 2002, we have manipulated the form of N deposition to an ombrotrophic bog, Whim, on deep peat in southern Scotland, with low ambient N (wet + dry = 8 kg N ha^?1 yr^?1) and S (4 kg S ha^?1 yr^?1) deposition. A gradient of ammonia (NH₃, dry N), from 70 kg N ha^?1 yr^?1 down to background, 3–4 kg N ha^?1 yr^?1 was generated by free air release. Wet ammonium (NH₄⁺, wet N) was provided to replicate plots in a fine rainwater spray (NH₄Cl at +8, +24, +56 kg N ha^?1 yr^?1). Automated treatments are coupled to meteorological conditions, in a globally unique, field experiment. Ammonia concentrations were converted to NH₃‐N deposition (kg N ha^?1) using a site/vegetation specific parameterization. Within 3 years, exposure to relatively modest deposition of NH₃, 20–56 kg NH₃‐N ha^?1 yr^?1 led to dramatic reductions in species cover, with almost total loss of Calluna vulgaris, Sphagnum capillifolium and Cladonia portentosa. These effects appear to result from direct foliar uptake and interaction with abiotic and biotic stresses, rather than via effects on the soil. Additional wet N by contrast, significantly increased Calluna cover after 5 years at the 56 kg N dose, but reduced cover of Sphagnum and Cladonia. Cover reductions caused by wet N were significantly different from and much smaller than those caused by equivalent dry N doses. The effects of gaseous NH₃ described here, highlight the potential for ammonia to destroy acid heathland and peat bog ecosystems. Separating the effects of gaseous ammonia and wet ammonium deposition, for a peat bog, has significant implications for regulatory bodies and conservation agencies.     

Residue incorporation depth is a controlling factor of earthworm‐induced nitrous oxide emissions

Earthworms can increase nitrous oxide (N₂O) emissions, particularly in no‐tillage systems where earthworms are abundant. Here, we study the effect of residue incorporation depth on earthworm‐induced N₂O emissions. We hypothesized that cumulative N₂O emissions decrease with residue incorporation depth, because (i) increased water filled pore space (WFPS) in deeper soil layers leads to higher denitrification rates as well as more complete denitrification; and (ii) the longer upward diffusion path increases N₂O reduction to N₂. Two 84‐day laboratory mesocosm experiments were conducted. First, we manually incorporated maize (Zea mays L.) residue at different soil depths (incorporation experiment). Second, ¹³C‐enriched maize residue was applied to the soil surface and anecic species Lumbricus terrestris (L.) and epigeic species Lumbricus rubellus (Hoffmeister) were confined to different soil depths (earthworm experiment). Residue incorporation depth affected cumulative N₂O emissions in both experiments (P < 0.001). In the incorporation experiment, N₂O emissions decreased from 4.91 mg N₂O–N kg^?1 soil (surface application) to 2.71 mg N₂O–N kg^?1 soil (40–50 cm incorporation). In the earthworm experiment, N₂O emissions from L. terrestris decreased from 3.87 mg N₂O–N kg^?1 soil (confined to 0–10 cm) to 2.01 mg N₂O–N kg^?1 soil (confined to 0–30 cm). Both experimental setups resulted in dissimilar WFPS profiles that affected N₂O dynamics. We also found significant differences in residue C recovery in soil organic matter between L. terrestris (28–41%) and L. rubellus (56%). We conclude that (i) N₂O emissions decrease with residue incorporation depth, although this effect was complicated by dissimilar WFPS profiles; and (ii) larger residue C incorporation by L. rubellus than L. terrestris indicates that earthworm species differ in their C stabilization potential. Our findings underline the importance of studying earthworm diversity in the context of greenhouse gas emissions from agro‐ecosystems.     

ROLE OF GLUTAMATE DEHYDROGENASE AND GLUTAMINE SYNTHETASE IN CHLORELLA VULGARIS DURING ASSIMILATION OF AMMONIUM WHEN JOINTLY IMMOBILIZED WITH THE MICROALGAE‐GROWTH‐PROMOTING BACTERIUM AZOSPIRILLUM BRASILENSE1

Enzymatic activities of glutamate dehydrogenase (GDH) and glutamine synthetase (GS) participating in the nitrogen metabolism and related ammonium absorption were assayed after the microalga Chlorella vulgaris Beij. was jointly immobilized with the microalgae‐growth‐promoting bacterium Azospirillum brasilense. At initial concentrations of 3, 6, and 10 mg · L^?1 NH₄⁺, joint immobilization enhances growth of C. vulgaris but does not affect ammonium absorption capacity of the microalga. However, at 8 mg · L^?1 NH₄⁺, joint immobilization enhanced ammonium absorption by the microalga without affecting the growth of the microalgal population. Correlations between absorption of ammonium per cell and per culture showed direct (negative and positive) linear correlations between these parameters and microalga populations at 3, 6, and 10 mg · L^?1 NH₄⁺, but not at 8 mg · L^?1 NH₄⁺, where the highest absorption of ammonium occurred. In all cultures, immobilized and jointly immobilized, having the four initial ammonium concentrations, enzymatic activities of Chlorella are affected by A. brasilense. Regardless of the initial concentration of ammonium, GS activity in C. vulgaris was always higher when jointly immobilized and determined on a per‐cell basis. When jointly immobilized, only at an initial concentration of 8 mg · L^?1 NH₄⁺ was GDH activity per cell higher.     

Continuous multistep versus fed‐batch production of ethanol and xylitol in a simulated medium of sugarcane bagasse hydrolyzates

Co‐cultures for simultaneous production of ethanol and xylitol were studied under different operation bioreactor modes using Candida tropicalis IEC5‐ITV and Saccharomyces cerevisiae ITV01‐RD in a simulated medium of sugarcane bagasse hydrolyzates. Xylitol and ethanol tolerance by S. cerevisiae and C. tropicalis, respectively, was evaluated. The results showed that C. tropicalis was sensitive to ethanol concentrations up to 30 g/L, while xylitol had no effect on S. cerevisiae viability and metabolism. The best condition found for simultaneous culture was S. cerevisiae co‐culture and C. tropicalis sequential cultivation at 24 h. Under these conditions, productivity and yield for ethanol were Q_EtOH = 0.72 g L^?1 h^?1 and Y_EtOH/s = 0.37 g/g, and for xylitol, Q_XylOH = 0.10 g L^?1 h^?1 and Y_XylOH/S = 0.31 g/g, respectively; using fed‐batch culture, the results were Q_EtOH = 0.87 g L^?1 h^?1 and Y_EtOH/s = 0.44 g L^?1 h^?1, and Q_EtOH = 0.27 g L^?1 h^?1 and Y_EtOH/s = 0.57 g/g, respectively. Maximum volumetric productivity in continuous multistep cultures of ethanol and xylitol was at dilution rates of 0.131 and 0.074 h^?1, respectively. Continuous multistep production, Q_EtOH increased up to 50% more than in fed‐batch culture, even though xylitol yield remained unchanged.     

15N-determined dinitrogen fixation potential of genetically diverse bean lines (Phaseolus vulgaris L.)

Improvement of dinitrogen fixation in beans (Phaseolus vulgaris L.) will depend on the selection of superior plant genotypes and the presence of efficient rhizobial strains. This study was conducted to evaluate diverse bean lines for N₂ fixation potential using the¹⁵N-depleted dilution technique under field conditions in Wisconsin, USA. Plants of 21 bean lines and three non-nodulating isolines of soybean received appliin Wisconsin, USA. Plants of 21 bean lines and three non-nodulating isolines of soybean received applications of¹⁵N-depleted ammonium sulphate. Shoots harvested at the V₆, R₃ and R₇ stages and dry seeds were analyzed for total N using the Kjeldahl procedure, and the ratio of¹⁵N to¹⁴N was determind on a MAT 250 mass spectrometer. Nodule occupancy of the applied strain ofR. leguminosarum biovarphaseoli, CIAT 899, was determined in five of the bean lines. Total shoot N content showed a pattern of accumulation similar to shoot dry weight and fixed N₂ in the shoot. Based on shoot total N, N₂ fixed in the shoot and shoot dry weight Riz 30 and Preto Cariri were identified as being as good fixers as Puebla 152 and Cargamanto appear to begin N₂ fixation early. Furthermore, some bean lines that fixed considerable N₂ did not translocate a large amount of N to the grains. Preto Cariri accumulated 21.2 kg N ha⁻¹ in the seeds compared to Puebla 152 which accumulated 43.8 kg N ha⁻¹ of the fixed N₂ into the grains. At the early sampling, Puebla 152 and 22–27 had a considerable higher percentage of their crown nodules formed by the inoculant strain CIAT 899, than did Rio Tibagi which has been considered a poor N₂ fixer.     

Effects of 5-aminolevulinic acid on Swiss chard (Beta vulgaris L. subsp. cicla) seedling growth under saline conditions

Salinity is a widespread adverse environmental problem globally, and significantly limits crop production. In this study, the possibility of enhancing salinity stress tolerance of Swiss chard (Beta vulgaris L. var. cicla) by 5-aminolevulinic acid (ALA) foliar application was investigated. The Swiss chard plants were grown in hydroponic culture. Twelve-week-old uniform seedlings were treated by 0 and 40 mM saline regimes generated by the mixture of sodium chloride and sodium sulfate (molar ratio NaCl:Na₂SO₄ = 9:1), and were foliar-sprayed with 0 and 60 μM L^?1 ALA (every 3 days) for 6 days; then the plants were treated for another 7 days (every 3 day) with increased concentration of salinity and ALA, 80 mM and 120 μM L^?1. Salinity without ALA application significantly decreased plant growth [43 % in shoot dry weight (DW), 21 % in root DW, 24 % in relative growth rate (RGR), 43 % in leaf area (LA)], water uptake [20.8 % in relative water content (RWC), 47.9 % in osmotic potential (OP)], chlorophyll (Chl) a content (10 %), P_n (36 %), G_s (72 %) and T_r (59 %) compared with those in control plants; however, under saline conditions, ALA foliar application improved plant growth (49.7 % in shoot DW, 27 % in root DW, 42.3 % in RGR, 72.1 % in LA) and increased RWC (12 %), Chl a content (10 %) and photosynthetic parameters (27 % in P_n, 28 % in G_s, 14 % in T_r) compared with those in untreated plants. Salinity significantly increased Na⁺ content, resulting in the reduction of Mg²⁺ and K⁺ contents. ALA foliar application alleviated ionic toxicity through the reduction of Na⁺ content and Na⁺/K⁺ ratio. On the other hand, it increased total nitrogen and glycine betaine (GB) content. ALA foliar application slightly reduced malondialdehyde (MDA) content, indicating that ALA has the potential to alleviate oxidative stress in salinity-stressed Swiss chard.     

Biomass production and nitrate metabolism of Atriplex hortensis L. (C3 plant) and Amaranthus retroflexus L. (C4 plant) in cultures at different levels of nitrogen supply

Summary Pure and mixed cultures of the dicotyledons Atriplex hortensis L. (C₃ plant) and Amaranthus retroflexus L. (C₄ plant) were maintained under open air conditions in standard soil at low and high nitrogen supply levels.A comparison of shoot dry weight and shoot length in the various series shows that the growth of the aboveground parts of both species was severely reduced under low N conditions. In both pure and mixed cultures the differences resulting from low N vs. high N conditions was less pronounced with Atriplex (C₃ plant) than with Amaranthus (C₄ plant). The root dry weight of the two species was not reduced so much under low N conditions as was the shoot dry weight. The low N plants were found to contain a larger proportion of their biomass in the roots than did the high N plants. In general the root proportion of Atriplex was greater than that of Amaranthus. The contents of organic nitrogen and nitrate and the nitrate reductase activity (NRA) per g dry weight of both species decreased continually throughout the experiments. With the exception of young plants, the low N plants always had tower contents of organic nitrogen and nitrate and nitrate reductase activities than did the high N plants. The highest values of NRA were measured in the leaf laminae. The eaves also exhibited the highest concentrations of organic nitrogen. The highest nitrate concentrations, however, were observed in the shoot axis, and in most cases the lowest nitrate values were found in the laminae. At the end of ne growing season this pattern was found to have been reversed with Atriplex, but not with Amaranthus. Thus Atriplex was able to maintain a higher NRA in the laminae than Amaranthus under low N conditions.The transpiration per leaf area of the C₄ plant Amaranthus during the course of a day was substantially lower than that of the C₃ plant Atriplex. There were no significant differences in transpiration between the low N and high N series of Amaranthus. The low N plants of Atriplex, however, clearly showed in most cases higher transpiration rates than the corresponding high N plants. These different transpiration rates of the high N and the low N Atriplex plants were also reflected in a distinct ¹³C discrimination.The sum of these results points to the conclusion that the C₃ plant Atriplex hortensis can maintain a better internal inorganic nitrogen supply than the C₄ plant Amaranthus retroflexus under low N conditions and an ample water supply, due to the larger root proportion and the more pronounced and flexible transpiration of the C₃ plant.Dedicated to Prof. Dr. Karl Mägdefrau, Deisenhofen, on the ocasion of his 80th birthday     

New luminol chemiluminescence reaction using diperiodatoargentate as oxidate for the determination of amikacin sulfate

A new chemiluminescence (CL) reaction between luminol and diperiodatoargentate {K₂ [Ag (H₂IO₆) (OH) ₂]} was observed in alkaline medium. The CL intensity could be greatly enhanced by amikacin sulfate. Therefore a new CL method for the determination of amikacin sulfate was built by combining with flow injection technology. A possible mechanism of the CL reaction was proposed via the investigation of the CL kinetic characteristics, the CL spectrum and the UV absorption spectra of some related substance. The concentration range of linear response was 5.1 × 10^?8 to 5.1 × 10^?6 mol L^?1 with a detection limit of 1.9 × 10^?8 mol L^?1 (3σ). The proposed method had good reproducibility with a relative standard deviation of 2.8% (n = 7) for 5.1 × 10^?7 mol L^?1 of amikacin sulfate. It was successfully applied to determine amikacin sulfate in serum. Copyright © 2009 John Wiley & Sons, Ltd.     

Sucrose,benzylaminopurine and photoperiod effects on in vitro culture of Kaempferia galanga Linn

Abstract

Kaempferia galanga is a monocotyledonous plant of the Zingiberaceae family, commonly utilized for medicinal purposes. This study evaluates the effect of different concentrations of sucrose, benzylaminopurine (BA) and photoperiod on in vitro propagation of K. galanga. Murashige and Skoog (MS) medium supplemented with 5 mg L^?1 BA and 30 g L^?1 sucrose, and a photoperiod with 4 h of light induced the highest shoot proliferation (7.4 ± 1.0 shoots/explant) and the highest number of roots/shoot (31.3 ± 3.2). On the contrary, the maximum shoot height (4.7 ± 0.7 cm) and the highest number of leaves/shoot (4.7 ± 0.2) were obtained from cultures using MS medium supplemented with 30 g L^?1 sucrose but without BA, and exposed to 16 h of light. Hence MS medium supplemented with 5 mg L^?1 BA and 30 g L^?1 sucrose, and incubated under a 4 h light/20 h dark photoperiod was chosen as the optimal protocol for mass multiplication of K. galanga. This in-vitro technique can facilitate the production of a large number of uniform plants of K. galanga, irrespective of the seasonal factor, and could be used as a tool for conservation of the species.     

Seasonal N uptake and N2fixation by common and adzuki bean at various spacings

The adzuki bean (Vigna angularis (Wild.) Ohwi and Ohashi) and common bean (Phaseolus vulgaris L.) have a high physiological demand for N. A 2-year field study was conducted to investigate the seasonal change of available soil N and symbiotic N₂ fixation usage. The beans were seeded at two densities, 22.2 plants m^–2 with a row spacing of 0.3 m and 11.1 plants m^–2 with a row spacing of 0.6 m. The amount of fixed N₂ in the shoot was calculated using the ¹⁵N natural abundance method. The common bean demonstrated low N₂ fixation and the ability to accumulate high levels of soil N. Soil nitrate under the common bean was continually absorbed. The adzuki bean, on the other hand, had a remarkable peak of N accumulation in the early reproductive stage. This was mainly due to N₂ fixation, though the soil nitrate level was high. Narrowing the plant row spacing increased the dry matter yield of both species, but the origin of the increased N differed between the species. For the first 77 DAP in 1999 (73 DAP in 2000) the N increase for both beans was due to both soil and atmospheric N₂. At harvest, though, the increase of N in common bean was mainly due to soil N, while that in adzuki bean was mainly due to atmospheric N₂. It can be concluded that the low symbiotic N₂ fixation ability of common bean was due to its high soil N uptake ability and constant N accumulation, which enabled an efficient soil N absorption. Adzuki bean absorbed N mainly for a short period and depended more on symbiotically fixed N₂ and, in contrast to common bean, left a high level of NO₃-N remaining in the soil after cropping.     

Interactive effects of nitrogen and phosphorus on the acclimation potential of foliage photosynthetic properties of cork oak,Quercus suber,to elevated atmospheric CO2 concentrations

Leaf gas-exchange and chemical composition were investigated in seedlings of Quercus suber L. grown for 21 months either at elevated (700 μmol mol^–1) or normal (350 μmol mol^–1) ambient atmospheric CO₂ concentrations, [CO₂], in a sandy nutrient-poor soil with either ‘high’ N (0.3 mol N m^–3 in the irrigation solution) or with ‘low’ N (0.05 mol N m^–3) and with a constant suboptimal concentration of the other macro- and micronutrients. Although elevated [CO₂] yielded the greatest total plant biomass in ‘high’ nitrogen treatment, it resulted in lower leaf nutrient concentrations in all cases, independent of the nutrient addition regime, and in greater nonstructural carbohydrate concentrations. By contrast, nitrogen treatment did not affect foliar N concentrations, but resulted in lower phosphorus concentrations, suggesting that under lower N, P use-efficiency in foliar biomass production was lower. Phosphorus deficiency was evident in all treatments, as photosynthesis became CO₂ insensitive at intercellular CO₂ concentrations larger than ≈ 300 μmol mol^–1, and net assimilation rates measured at an ambient [CO₂] of 350 μmol mol^–1 or at 700 μmol mol^–1 were not significantly different. Moreover, there was a positive correlation of foliar P with maximum Rubisco (Ribulose-1,5-bisphosphate carboxylase/oxygenase) carboxylase activity (V_cmax), which potentially limits photosynthesis at low [CO₂], and the capacities of photosynthetic electron transport (J_max) and phosphate utilization (P_max), which are potentially limiting at high [CO₂]. None of these potential limits was correlated with foliar nitrogen concentration, indicating that photosynthetic N use-efficiency was directly dependent on foliar P availability. Though the tendencies were towards lower capacities of potential limitations of photosynthesis in high [CO₂] grown specimens, the effects were statistically insignificant, because of (i) large within-treatment variability related to foliar P, and (ii) small decreases in P/N ratio with increasing [CO₂], resulting in balanced changes in other foliar compounds potentially limiting carbon acquisition. The results of the current study indicate that under P-deficiency, the down-regulation of excess biochemical capacities proceeds in a similar manner in leaves grown under normal and elevated [CO₂], and also that foliar P/N ratios for optimum photosynthesis are likely to increase with increasing growth CO₂ concentrations. Symbols: A, net assimilation rate (μmol m^–2 s^–1); A_max, light-saturated A (μmol m^–2 s^–1); α, initial quantum yield at saturating [CO₂] and for an incident Q (mol mol^–1); [CO₂], atmospheric CO₂ concentration (μmol mol^–1); C_i, intercellular CO₂ concentration (μmol mol^–1); C_a, CO₂ concentration in the gas-exchange cuvette (μmol mol^–1); F_B, fraction of leaf N in ‘photoenergetics’; F_L, fraction of leaf N in light harvesting; F_R, fraction of leaf N in Rubisco; Γ*, CO₂ compensation concentration in the absence of R_d (μmol mol^–1); J_max*, capacity for photosynthetic electron transport; J_mc, capacity for photosynthetic electron transport per unit cytochrome f (mol e^–[mol cyt f]^–1 s^–1); K_c, Michaelis-Menten constant for carboxylation (μmol mol^–1); K_o, Michaelis-Menten constant for oxygenation (mmol mol^–1); M_A, leaf dry mass per area (g m^–2); O, intercellular oxygen concentration (mmol mol^–1); [P_i], concentration of inorganic phosphate (mM); P_max*, capacity for phosphate utilization; Q, photosynthetically active quantum flux density (μmol m^–2 s^–1); R_d*, day respiration (CO₂ evolution from nonphotorespiratory processes continuing in the light); Rubisco, ribulose-1,5-bisphosphate carboxylase/oxygenase; RUBP, ribulose-1,5-bisphosphate; T_l, leaf temperature (°C); U_TPU*, rate of triose phosphate utilization; V_cmax*, maximum Rubisco carboxylase activity; V_cr, specific activity of Rubisco (μmol CO₂[g Rubisco]^–1 s^–1] *given in either μmol m^–2 s^–1 or in μmol g^–1 s^–1 as described in the text.