chlorophyll-a and ammonium-nitrate

Bradyrhizobium sp. strain SUTN9-2 was confirmed as rice endophytic bacteria and also as rice growth promotion agent. SUTN9-2 showed the capability of plant growth promotion characteristics, such as indole-3-acetic acid (IAA) and 1-amino-cyclopropane-1-carboxylic acid (ACC) deaminase productions and nitrogen fixation. In this study, the ability of SUTN9-2 to stimulate rice growth was investigated at different stages with N-free and NH

Topics: Bradyrhizobium; Carbon-Carbon Lyases; Chlorophyll; Indoleacetic Acids; Nitrates; Nitrogen Fixation; Oryza; Plant Development; Seedlings

Hydraulically connected wetland microcosms vegetated with either Typha latifolia or Myriophyllum aquaticum were amended with an NH

Topics: Biological Assay; Chlorophyll; Chlorophyll A; Nitrates; Nitrogen; Permethrin; Phytoplankton; Toxicity Tests; Typhaceae; Water Pollutants, Chemical; Wetlands

Biological soil crusts (BSCs) cover >35% of the Earth's land area and contribute to important ecological functions in arid and semiarid ecosystems, including erosion reduction, hydrological cycling, and nutrient cycling. Artificial rapid cultivation of BSCs can provide a novel alternative to traditional biological methods for controlling soil and water loss such as the planting of trees, shrubs, and grasses. At present, little is known regarding the cultivation of BSCs in the field due to lack of knowledge regarding the influencing factors that control BSCs growth. Thus, we determined the effects of various environmental factors (shade; watering; N, P, K, and Ca concentrations) on the growth of cyanobacteria-dominated BSCs from the Sonoran Desert in the southwestern United States. The soil surface changes and chlorophyll a concentrations were used as proxies of BSC growth and development. After 4 months, five factors were found to impact BSC growth with the following order of importance: NH4NO3 ≈ watering frequency>shading>CaCO3 ≈ KH2PO4. The soil water content was the primary positive factor affecting BSC growth, and BSCs that were watered every 5 days harbored greater biomass than those watered every 10 days. Groups that received NH4NO3 consistently exhibited poor growth, suggesting that fixed N amendment may suppress BSC growth. The effect of shading on the BSC biomass was inconsistent and depended on many factors including the soil water content and availability of nutrients. KH2PO4 and CaCO3 had nonsignificant effects on BSC growth. Collectively, our results indicate that the rapid restoration of BSCs can be controlled and realized by artificial "broadcasting" cultivation through the optimization of environmental factors.

Topics: Biomass; Calcium Carbonate; Chlorophyll; Chlorophyll A; Cyanobacteria; Desert Climate; Ecology; Ecosystem; Lichens; Light; Nitrates; Phosphates; Poaceae; Potassium Compounds; Soil Microbiology; Southwestern United States; Temperature; Trees; Water

In this work we studied the influence of exogenous ammonium on the total protein and chlorophyll contents, on the number of ribosomes and on the expression of ribosomal genes encoding the small subunit 18S rRNA and rpS6 protein in unicellular green alga Chlamydomonas reinhardtii and in callus tissue of Glycine max. Comparative analysis of two sets of data showed that although the lack of ammonium resulted in reduction of the number of ribosomes in alga and plant cells, this effect was not caused by decreasing of the expression level of the ribosomal genes. Possible mechanisms of the ammonium regulatory role in the ribosome biogenesis are discussed.

Topics: Algal Proteins; Chlamydomonas reinhardtii; Chlorophyll; Gene Expression; Glycine max; Nitrates; Plant Proteins; Ribosomal Protein S6; Ribosomes; RNA, Ribosomal, 18S; Species Specificity

This study investigated if some nitrogen (N) compounds commonly used as fertilizers (KNO3, NH4NO3, (NH4)2SO4) cause chlorophyll degradation in the N-tolerant lichen Xanthoria parietina and if polyamines are responsible for the N-tolerance of this species. The results showed that N excess does not cause chlorophyll degradation and suggested the absence of kinetics in the mode of action of the N compounds tested. External supply of inhibitors of polyamine biosynthesis prior to N treatments did not cause any change in the response of chlorophyll integrity, suggesting that at least chlorophyll integrity is not controlled by polyamines.

Topics: Ammonium Sulfate; Ascomycota; Chlorophyll; Dose-Response Relationship, Drug; Fertilizers; Nitrates; Nitrogen; Polyamines; Potassium Compounds; Time Factors

The sensitivity of lichens measuring photosynthetic efficiency and polyamines as modulator of nitrogen stress tolerance was investigated. Two lichen species with a markedly different tolerance to nitrogen compounds, namely Evernia prunastri (L.) Ach. and Xanthoria parietina (L.) Th.Fr., were incubated with deionized water (control) and solutions of KNO(3), NH(4)NO(3) and (NH(4))(2)SO(4) and then exposed to different light conditions. The F(v)/F(m) parameter (maximum quantum efficiency of photosystem II) was used as stress indicator. The results showed that F(v)/F(m) values, in the produced experimental conditions, were independent from the light gradient. Photosynthetic efficiency of E. prunastri was impaired by high ammonium concentrations, while nitrate had no effect; X. parietina was hardly influenced by nitrogen compounds. External supply of polyamines reduced the sensitivity of E. prunastri, while polyamine inhibitors reduced the tolerance of X. parietina to NH(4)(+), suggesting that polyamines play an important role in modulating the sensitivity/tolerance to nitrogen stress.

Topics: Adaptation, Physiological; Ammonium Sulfate; Chlorophyll; Chlorophyll A; Dose-Response Relationship, Drug; Environmental Monitoring; Environmental Pollutants; Lichens; Light; Nitrates; Nitrogen; Photosynthesis; Photosystem II Protein Complex; Polyamines; Potassium Compounds; Stress, Physiological; Time Factors

The aim of this study was to compare the physiological responses to increased nitrogen (N) supply between the nitrophytic lichen Xanthoria parietina (L.) Th. Fr. and the acidophytic lichen Evernia prunastri (L.) Ach. The two lichens were exposed to a weekly dosage of 0.05, 0.1, 0.2, 0.6 or 2.4 g N m(-2) for 2 months, administered as NH(4)NO(3) dissolved in artificial rainwater (1 l m(-2)). After the treatments, in vivo chlorophyll a fluorescence was determined to assess vitality; concentrations of total N, ammonium, nitrate and dominant amino acids, including glutamate, glutamine and arginine, were quantified in order to follow changes in N status; and the polyols ribitol, arabitol and mannitol were quantified to follow changes in the lichens' carbon (C) status. The uptake of N was quantified by labelling the fertiliser with (15)N in the ammonium position; chlorophyll a was used as an indirect marker for algal activity, and ergosterol as an indirect marker of fungal activity. Nitrogen uptake was higher in E. prunastri than in X. parietina, although the latter species may have used the mannitol reserves to obtain C skeletons and energy for N assimilation. Chlorophyll a and ergosterol concentrations remained unaltered in X. parietina irrespective of N dosage while ergosterol decreased with increasing N uptake in E. prunastri. The latter species had accumulated a large pool of ammonium at the highest N dosage, whilst in X. parietina a significant nitrate pool was instead observed. Taken together, these short-term responses to high N supply observed in the two lichens, and the differences between them, can partly explain the higher tolerance of X. parietina towards increased atmospheric N levels.

Topics: Amino Acids; Chlorophyll; Chlorophyll A; Ergosterol; Fertilizers; Lichens; Mannitol; Nitrates; Nitrogen; Quaternary Ammonium Compounds; Ribitol; Sugar Alcohols

Tobacco transformants that express an antisense RBCS construct were used to investigate the consequences of a lesion in photosynthetic carbon metabolism for nitrogen metabolism and secondary metabolism. The results show that an inhibition of photosynthesis and decrease in sugar levels leads to a general inhibition of nitrogen metabolism, and dramatic changes in the levels of secondary metabolites. The response was particularly clear in plants that received excess nitrogen. In these conditions, a decrease of Rubisco activity led to an inhibition of nitrate reductase activity, accumulation of nitrate, a decrease of amino acid levels that was larger than the decrease of sugars, and a large decrease of chlorogenic acid and of nicotine, which are the major carbon- and nitrogen-rich secondary metabolites in tobacco leaves, respectively. Similar changes were seen when nitrogen-replete wild-type tobacco was grown in low light. The inhibition of nitrogen metabolism was partly masked when wild-type plants and antisense RBCS transformants were compared in marginal or in limiting nitrogen, because the lower growth rate of the transformants alleviated the nitrogen deficiency, leading to an increase of amino acids. In these conditions, chlorogenic acid always decreased but the decrease of nicotine was ameliorated or reversed. When the changes in internal pools are compared across all the genotypes and growth conditions, two conclusions emerge. First, decreased levels of primary metabolites lead to a dramatic decrease in the levels of secondary metabolites. Second, changes of the amino acid : sugar ratio are accompanied by changes of the nicotine:chlorogenic acid ratio.

Topics: Amino Acids; Carbohydrate Metabolism; Chlorogenic Acid; Chlorophyll; DNA, Antisense; Ketoglutaric Acids; Light; Nicotiana; Nicotine; Nitrate Reductase; Nitrate Reductases; Nitrates; Photosynthesis; Plant Leaves; Plant Proteins; Plants, Genetically Modified; Potassium Compounds; Propanols; Ribulose-Bisphosphate Carboxylase; Rutin