Jóska Gerendás

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Ammonium-induced changes in the cytoplasmic and vacuolar pH values of excised maize (Zea mays L.) root tips, measured by in vivo 31P nuclear magnetic resonance (NMR) spectroscopy, were correlated with the ammonium content of the tissue, determined by 14N NMR. Calculations based on these measurements indicated that the pH changes observed during exposure to(More)
The effect of Ni supply on growth, N metabolism and leaf urease activity of six plant species (rye, wheat, soybean, rape, zucchini and sunflower) grown on urea-based nutrient solutions was investigated. Activity of urease, which is activated by Ni, was hardly detectable in plants of all six species grown without supplementary Ni. As a consequence(More)
BACKGROUND AND AIMS Tea (Camellia sinensis) is considered to be acid tolerant and prefers ammonium nutrition, but the interaction between root zone acidity and N form is not properly understood. The present study was performed to characterize their interaction with respect to growth and mineral nutrition. METHODS Tea plants were hydroponically cultured(More)
The effect of Ni supply on growth and N metabolism of zucchini plants grown with either NH4NO3 or urea as sole N source was investigated. Dry matter production of plants grown with NH4NO3 was not affected by the Ni status, while urea-based nutrition led to reduced growth, particularly when plants were grown without Ni supplementation. The activity of(More)
In order to evaluate whether Co can functionally replace Ni in urease, as suggested by Watanabe et al. (Soil Sci. Plant Nutr. (1994) 40, 545–548), zucchini and soybean plants were grown in purified nutrient solutions containing nitrate and ammonium as sole N source supplemented either with 0.05 mmol m-3 Ni or Co or with no supplementation (control). In(More)
Wheat (Triticum aestivum L.) was grown in nutrient solution with low or high N supply (NH4NO3 as N source). To further evaluate the influence of N form and its interaction with the nutrient solution pH, wheat plants were grown with NH 4 + or NO 3 - either in an conventional nutrient solution or in a nutrient solution in which the pH was maintained at pH 6.5(More)
Safflower (Carthamus tinctorius L.) represents an important oil crop internationally and may have a certain production potential under low input conditions, particularly in organic farming systems, where the putatively low nutrient requirement would be an advantage. However, little is known about the nutrient requirements of safflower. This study was(More)
In vivo 31P nuclear magnetic resonance (NMR) was used to characterize the effect of the N form (NO3 vs. NH4) and the external pH (4, 6, and 8), on the intracellular pH of root tips (0–5 mm) and root segments (5–30 mm). Ammonium-grown root tips were the most sensitive to changes in the external pH. In vivo 15N NMR was used to characterize the pathway of(More)
The concentrations of free amino acids (AA) and polyphenols (PP) are important determinants of green tea quality. Levels of AA and PP are governed interactively by nitrogen (N) supply and carbon (C) status, so the impact of C/N allocation on green tea quality was investigated in saplings cultivated hydroponically with 0.3, 0.75, 1.5 or 4.5 mmol l(-1) N.(More)