Nitrogen Enzyme Activities Research Articles

Substitution of Inorganic Fertilizer with Organic Fertilizer Influences Soil Carbon and Nitrogen Content and Enzyme Activity under Rubber Plantation

Conventional fertilization practices can lead to many ecological problems, such as nutrient imbalance, soil acidity, and reduced soil fertility, in natural rubber plantations. To address these challenges, a field investigation was strategically carried out to substitute inorganic fertilizer with organic fertilizer, consisting of six treatments: no fertilization (CK), inorganic fertilizer (NPK), 25% replacement of inorganic through organic (25% manure (M)), 50% replacement of inorganic through organic (50% manure (M)), 75% replacement of inorganic through organic (75% manure (M)), and 100% organic fertilizer (100% manure). The soil physicochemical properties (soil organic carbon (SOC), total nitrogen (TN), mineral nitrogen (N), ammonium nitrogen (NH4+-N), and nitrate nitrogen (NO3−-N)), C:N, pH, and the carbon- and nitrogen-converting enzymes β-1,4-glucosidase (BG), N-acetylglucosaminidase (NAG) and L-leucine aminopeptidase (LAP) were all determined. The partial substitution of inorganic fertilizer with organic fertilizer (i.e., 75% M at surface soil layer) showed higher SOC (14.52 g·kg−1), TN (1.06 g·kg−1), N (20.07 mg·kg−1), C:N (14.63), NH4+-N (10.63 mg·kg−1), and NO3−-N (11.06 mg·kg−1) than NPK and CK. This increase in physicochemical properties after partial replacement of inorganic with organic fertilizer resulted from higher carbon and nitrogen enzyme activities (BG (143.17·nmol·g−1·h−1), NAG (153.96 nmol·g−1·h−1), and LAP (153.48 nmol·g−1·h−1)) compared to NPK and CK. Further, the Pearson correlation and redundancy analysis (RDA) analyses confirmed a significant positive correlation between SOC, N, and soil enzymes. This study presents a new strategy for assessing the impact of partially replacing inorganic fertilizer with organic fertilizer in rubber plantations in tropical regions, mainly by modifying the soil nutrient composition.

Effects of Nitrogen Application Strategy on Nitrogen Enzyme Activities and Protein Content in Spring Wheat Grain

The aim of this study was to determine the regulatory effect of different nitrogen (N) fertilizer application rates on the grain N metabolism enzymes and protein content of drip-irrigated spring wheat under the climatic conditions in Xinjiang, China. A split plot experiment was conducted with strong gluten wheat Xinchun 38 (XC 38) and medium gluten wheat Xinchun 49 (XC 49) as experimental materials. We set up seven nitrogen treatments, in amounts of 300 (Nck), 285 (N5), 270 (N10), 255 (N15), 240 (N20), 225 (N25) and 0 (N0) kg hm−2. The effects of N application rate on nitrate reductase (NR), glutamine synthetase (GS), glutamate-pyruvate aminotransferase (GPT), protein content, protein composition, and yield of wheat grain were studied. The results showed that NR, GS, GPT, protein content, albumin, globulin, glutenin, gliadin, and yield first increased and then decreased with the decrease in N application. Furthermore, different responses to different applications between different wheat varieties was also observed. The indexes of XC 38 reached the maximum in the N15 treatment, and the yield increased 2.99~81.45%. XC 49 showed the best indicators under the N25 treatment and the yield increased 0.37~71.29%. Under the same N level, all indicators of XC 38 were better than XC 49. Correlation analysis showed that the yield and protein yield were significantly positively correlated with NR, GS, and GPT. The interaction of N fertilizer and variety had significant effects on NR, GS, GPT, protein content, components, and yield. These results show that the protein content and yield of wheat grain can be improved by reasonably adjusting the N fertilizer application strategy.

Leaf characteristics of rice cultivars with a stronger yield response to projected increases in CO2 concentration.

Rising levels of atmospheric carbon dioxide (CO2 ) could, potentially, be exploited as a means to increase seed yield and maintain food security, especially for cereal grains. Although there have been multiple cultivar trials indicating that significant yield variation occurs, the basis for these differences has not been entirely elucidated. Here, we focus on two rice cultivars that differed in field trials to their yield sensitivity to elevated CO2 : Yangdao6hao (YD6), and Wuyunjing23 (W23) to assess whether observed yield differences (YD6 > W23) were associated with concurrent changes in leaf-level characteristics. At ambient levels of CO2 , leaf net photosynthesis (A) of YD6 was compatible with that of W23. However, at elevated CO2 , A was higher for YD6 relative to W23. The stability of leaf Rubisco content, biochemical characteristics (Vc,max, and Jmax ), nitrogen enzymatic activity, and chlorophyll concentration differed significantly, with greater values observed for YD6 relative to W23 at elevated CO2 . While such results are consistent with other studies, we also demonstrate that a higher ratio of carbon sinks (seed) to carbon sources (leaf), were linked to increases in cytokinins, and slower flag leaf senescence for the YD6 relative to the W23 cultivar at elevated CO2 . While additional data for a broader genetic selection are needed, the current study suggests a link between source/sink carbon assimilation, maintenance of photosynthetic biochemistry, and slower leaf senescence for rice cultivars that show a stronger yield response to projected CO2 levels. This information, in turn, may provide suitable metrics for future CO2 selection among rice cultivars.

Ecological features of urease activity distribution in technogenically altered soils of the Nikopol manganese ore basin

The challenge of degradation of natural ecosystems because of human activity is considered by the world community to the most serious problems facing mankind. As a result of mineral extraction, man-made landscapes and environmentally ruined areas replace natural habitats and agroecosystems; a whole spectrum of man-made processes are typical for such landscapes, which leads to a decrease in species richness and biological diversity within such areas. Degraded territories formed in the process of coal mining are often partially restored through remediation measures. During the implementation of the technical stage of remediation, substrates with different potential fertility having different environmental properties and quality are used. Specific features of distribution total, available nitrogen concentrations and levels of urease enzymatic activity at the layers of artificial soil, sod-lithogenic soils onto gray-green and red-brown clays and on loess-like loams in the Nikopol manganese ore basin are established. It is presented general assessment of technosol status by concentration of general easily hydrolysed nitrogen enzyme activity of urease and this enzyme enriches the soil with mineral nitrogen in the process of mineralization of organic substances. The level of activity of urease, investigated soils, determines the intensity of the direction of biochemical processes that affect soil fertility.High correlation between concentrations of soluble nitrogen and urease activity values by layers of artificial soil (r = 0.81), sod-lithogenic soils onto gray-green (r = 0.98), red-brown clays (r = 0.72) and onto loess-like loam (r = 0.85) were found. Tendency of decreasing hydrolytic enzyme activity, urease, with depth in all types of artificial soil studied was established. It has been established that biochemical diagnostics of technozem processes beyond the level of activity of the hydrolytic enzyme urease makes it possible to estimate the direction of changes at the layers of artificial soil, sod-lithogenic soils onto gray-green and red-brown clays and on loess-like loams. The recultivated soil has some what lower fertility and greater salimity at the lower horizons, but is capable of performing ecological functions and can not only be used for economic purposes, but also perform ecological functions.

Changes in growth, carbon and nitrogen enzyme activity and mRNA accumulation in the halophilic microalga Dunaliella viridis in response to NaCl stress

Many species of microalga Dunaliella exhibit a remarkable tolerance to salinity and are therefore ideal for probing the effects of salinity. In this work, we assessed the effects of NaCl stress on the growth, activity and mRNA level of carbon and nitrogen metabolism enzymes of D. viridis. The alga could grow over a salinity range of 0.44 mol L−1 to 3.00 mol L−1 NaCl, but the most rapid growth was observed at 1.00 mol L−1 NaCl, followed by 2.00 mol L−1 NaCl. Paralleling these growth patterns, the highest initial and total Rubisco activities were detected in the presence of 1.00 mol L−1 NaCl, decreasing to 37.33% and 26.39% of those values, respectively, in the presence of 3.00 mol L−1 NaCl, respectively. However, the highest extracellular carbonic anhydrase (CA) activity was measured in the presence of 2.00 mol L−1 NaCl, followed by 1.00 mol L−1 NaCl. Different from the two carbon enzymes, nitrate reductase (NR) activity showed a slight change under different NaCl concentrations. At the transcriptional level, the mRNAs of Rubisco large subunit (rbcL), and small subunit (rbcS), attained their highest abundances in the presence of 1.00 and 2.00 mol L−1 NaCl, respectively. The CA mRNA accumulation was induced from 0.44 mol L−1 to 3.00 mol L−1 NaCl, but the NR mRNA showed the decreasing tendency with the increasing salinity. In conclusion, the growth and carbon fixation enzyme of Rubisco displayed similar tendency in response to NaCl stress, CA was proved be salt-inducible within a certain salinity range and NR showed the least effect by NaCl in D. viridis.

Effect of furfural on nitrogen assimilating enzymes of the lactose utilizing yeasts Candida blankii 35 and Candida pseudotropicalis 11

The research was performed with two lactose-assimilating yeast strains— Candida blankii 35 with an oxidative metabolism and Candida pseudotropicalis 11 with a fermentative metabolism. The strains were cultivated in a chemostat under carbon limitation at dilution rates D = 0.1 and 0.25 h −1. After shock with 0.04% furfural, the changes of the following nitrogen enzyme activities were studied: NADPH-dependant glutamate dehydrogenase (NADPH-GDH), NADH-dependant glutamate dehydrogenase (NADH-GDH), glutamine synthetase (GS), glutamate synthase (GOGAT) and alanine dehydrogenase (ADH). Results show that during cultivation of C. blankii 35 at D = 0.1 h −1, furfural exhibits a clear inhibitory effect on the glutamate dehydrogenase and the alanine metabolite routes of ammonia ion assimilation. Furfural slows down the nitrogen assimilation of the strain through glutamate dehydrogenase and at D = 0.1 h −1 the GS/GOGAT system is activated. During the growth of the fermenting strain C. pseudotropicalis 11, furfural (0.04%) did not exhibit stable inhibitory effect on the enzyme activities of NADPH-GDH, NADH-GDH, GS, GOGAT and ADH. To the opposite, when reaching the steady state after furfural addition, their activities increased 6.3, 4.9, 5.6 and 4.1 times, respectively. At D = 0.25 h −1, GS activity was stronger affected by the dilution rate. Furfural did not inhibit the activity of NADPH-GDH, NADH-GDH and ADH. However, continuous inhibitory effect on GS and GOGAT activity was observed.