Search Results

You are looking at 31 - 40 of 927 items for :

  • "concentration" x
  • Biology and Life Sciences x
  • All content x
Clear All

Senescence of plant tissues is a natural process that may be accelerated by unfavourable environmental factors, including disbalanced mineral nutrition. During plant senescence, the concentration of reactive oxygen species (ROS) increases in the cells, whereas the concentration of cytokinins declines. Negative correlation between ROS, such as hydroxyl radical ( · OH), and concentration of cytokinins triggers the question whether the addition of cytokinins can reduce ROS production and/or its concentration. This would also reduce the level of lipid peroxidation (LP) in the senescing tissue, which is the final phase in the destruction of cell membranes by ROS.With the aim to address these questions, the effects of cytokinins (trans-zeatin, TZ, and benzyladenine, BA) on the concentration of · OH and LP were studied in wheat subjected to nitrogen deficiency. Foliar application of TZ reduced the concentration of · OH and the intensity of LP in the leaves of young wheat plants insufficiently supplied with nitrogen.

Restricted access

The number of stomata and the concentration of macro- and microelements in four new winter wheat genotypes: Lenta, Lara, Perla and Fiesta were investigated in two localities in Croatia in the 1997/98 growing season. The stomata number per mm2 was determined by a standard method. N was established by the micro-Kjeldahl method, P spectrophotometrically and K, Ca, Mg, Zn, Cu, Fe and Mn by the AAS method. The interrelation of the investigated parameters was determined by multiple regression and correlation analysis. The results obtained indicate that the number of stomata per mm2 and the macro- and microelement concentrations depended on the genotype, the phenophase and the locality. A statistically significant correlation was found between the stomata number per mm2 and the macro- (N, P, K, Ca, Mg) and microelement (Zn, Cu, Fe, Mn) concentrations.

Restricted access

A field experiment was conducted for 2 years at the Indian Agricultural Research Institute, New Delhi to study the effects of duration of variety and nitrogen fertilization on the Ca, Mg and S concentration and uptake in rice. In general, the concentrations of Ca, Mg and S were not significantly influenced by the duration of the rice variety. N fertilization had a tendency to increase the concentration of Ca, Mg and S at 45 days after transplanting as well as at harvest; however, the difference was significant only in the case of the Ca concentration in the grain and only when the N level was raised from 60 to 120 kg N/ha. The duration of the rice variety had a significant effect on the Ca, Mg and S uptake by the straw and grain at harvest, which was higher in the medium duration variety Pusa Basmati-1 than in Pusa Jaldi Dhan-1, mainly due to the higher yields obtained with the former cultivar. Nitrogen application significantly increased the Ca, Mg and S uptake at harvest mainly due to its increasing effects on the grain and straw yields of rice. The average uptake of Ca, Mg and S was 12.6, 13.6 and 3.5 kg per metric ton of grain, respectively.

Restricted access

293 297 Brkic I. — Simic D. — Zdunic Z. — Jambrovic A. — Ledencan T. — Kovacevic V. — Kadar I.: 2004. Genotypic variability of micronutrient element concentration in maize

Restricted access

concentration. Photosynthetica. 35: 637–640 Tuba Z. Enhanced water use efficiency in dry loess grassland species grown at elevated air CO2 concentration

Restricted access
Cereal Research Communications
Authors: Judit Szabó-Fodor, László Kametler, Roland Pósa, Rene Mamet, Veronika Rajli, Johann Bauer, Péter Horn, Ferenc Kovács, and Melinda Kovács

The absorption, distribution and elimination of fumonisin B 1 (FB 1 ) and its metabolites was investigated in pigs. For the determination of the absorption and biotransformation of FB 1 , T-cannula were implanted into the distal part of experimental pigs’ ileum and the total urine and faeces moiety was collected during the toxin feeding (45 mg FB 1 /kg diet, duration: 10 days) and in the subsequent elimination period (10 days). At the end of trial several organs, muscle and fat samples were also collected. The accumulative absorption of fumonisin B 1 was 4%. In the chymus, the FB 1 conversion to aminopentol (totally hydrolysed FB 1 ; AP 1 ) and partially hydrolysed FB 1 (PHFB 1 ) was 1% and 3.9%, respectively. Derivatives of FB 1 were mostly accumulated in the liver and kidney, while in negligible concentration could be detected in the muscle and fat samples. In the organs the efficacy of the FB 1 to AP 1 and PHFB 1 conversion was 30% and 20%, respectively. In the faecal content the main hydrolised product was PHFB 1 (47%), with 12% of AP 1 . 1.5% of the FB 1 quantity taken up was excreted with the urine, about 35% in hydrolyzed form. Detectable amounts of FB 1 and its metabolites were measured in most of the organs, in faeces and urine even 10 days after the feeding of the noncontaminated diet. As a general conclusion, the intestinal microbiota of pigs is able to transform the intact FB 1 to a similarly toxic substance (partially hydrolyzed FB 1 ) or to a more toxic metabolite (aminopentol).

Restricted access

The polyamine (PAs), putrescine (Put), spermidine (Spd) and spermine (Spm) are small aliphatic amines that ubiquitous in all living organisms. PA metabolism in higher plants is involved in both biotic and abiotic stress responses, and also influenced by nutrient deficiency. Accumulated evidence suggests that in plants the cellular titers of PAs are affected by various nitrogenous compounds. Therefore, the present study analyzed the effects of different nitrogen levels viz. recommended doses of nitrogen (RDN, 120 kg N/ha), sub-optimal N dose (RDN −25%, 90 kg N/ha) and supra-optimal N dose (RDN +25%, 150 kg N/ha) on PA metabolism in grains of six wheat genotypes at 15 days post anthesis (DPA) and 30 DPA. The activities of polyamine synthesizing enzymes (arginine decarboxylase, ornithine decarboxylase), catabolizing (diamine oxidase, polyamine oxidase) and the PA content were increased at supra-optimal nitrogen dose as compared to RDN. Whereas at sub-optimal nitrogen dose, higher activity of polyamine catabolizing enzymes results in speeding up oxidation of various PAs to cope up with nitrogen deficiency in plant. In relation to PA content, Put was found to be higher at early stage whereas Spd and Spm were found to be higher towards mature stages of grain indicating the use of Put in grain filling process. Highly significant correlation was observed between PA metabolism, yield and nitrogen use efficiency at sub-optimal N dose as compared to supra-optimal dose.

Restricted access

The present in vivo pot culture study showed hexavalent chromium (Cr+6) induced phytotoxic impacts and its translocation potential in 21 days old sesban (Sesbania sesban L. Merrill.) seedlings. Cr+6 showed significant growth retardation in 21 days old sesban (Sesbania sesban L. Merrill.) seedlings. Germination of seeds at 10,000 mg L−1 of Cr+6 exhibit 80% inhibition in germination. Seedling survival was 67% after 7 days of seedling exposure to 300 mg kg−1 of Cr+6. Shoot phytotoxicity was enhanced from 6% to 31% with elevated supply of Cr+6 from 10 mg kg−1 to 300 mg kg−1. Elevated supply of Cr+6 exhibited increasing and decreasing trends in % phytotoxicity and seedling tolerance index, respectively. Elevated supply of chromium showed decreased chlorophyll and catalase activities. Peroxidase activities in roots and leaves were significantly higher at increased supply of Cr+6. Cr bioconcentration in roots was nearly 10 times more than stems whereas leaves showed nearly double accumulation than stems. Tissue specific chromium bioaccumulation showed 53 and 12 times more in roots and shoots respectively at 300 mg kg−1 Cr+6 than control. The present study reveals potential of sesban for effective Cr translocation from roots to shoots as evident from their translocation factor and Total Accumulation Rate values.

Restricted access
Cereal Research Communications
Authors: S. Leon-Cisneros, A. Quirola-Garcés, J. Alvarez-Santana, N. Barriga-Medina, D. Ramirez-Villacís, M. Caviedes, L. Ramirez-Cárdenas, and A. Leon-Reyes

Anthocyanins are plants metabolites that are recognized by its red/purple coloration produced in flowers, seeds and leaves. These molecules are potentially important to the industry for its antioxidant capacity, disease prevention and as a natural dye. Currently, the production of anthocyanins is carried out using in vitro culture of Vitis vinifera and its yield is increased by using elicitors or stress factors. Zea mays is relevant due to its high content of cyanidin-3-β-glucoside anthocyanin. In the present study the production of cyanidin-3-β-glucoside was evaluated with different mechanisms of elicitation using in vivo and in vitro culture of purple and white maize varieties. The highest callus induction (85%) for white maize was obtained in MS medium supplemented with 2 mg/L of 2,4-Dichlorophenoxyacetic acid, while for purple maize (93%) was obtained in N6 medium with 2 mg/L of 2,4-Dichlorophenoxyacetic acid, using germinated seed as explant for both varieties. Methyl jasmonate was evaluated as an elicitation tool, however no cyanidin-3-β-glucoside was found to be accumulated or produced in vitro. In contrast, using germinated seeds and radicle tissue, elicitation using phosphorus deficiency treatment produced the highest cyanidin-3-β-glucoside accumulation (0.06 mg g−1) in white maize. No elicitation and further production of anthocyanins was found when purple maize were used using this method. Therefore, in vivo elicitation in white maize is a potential method to produce a stable anthocyanin that could be optimized for future applications.

Restricted access