This study was conducted to obtain information on the properties of the nitrate (NO3‐) uptake system in Vicia faba. The results showed that in plants grown in the absence of NO3‐, they cannot absorb it upon initial exposure to this anion. When this plant makes contact with environmental NO3‐, NO3‐uptake by the roots is progressively induced. However, in NO3‐‐grown plants, the uptake system is yet induced so they had the ability to take up NO3‐ at high rates from the beginning. The Michaelis’ constant (K,M) and maximum uptake rate (Vmax) were estimated from measurements of NO3‐ depletion in the uptake medium. The apparent KM value for net NO3‐ uptake in induced V. faba plants was 60 μM and the corresponding Vmax 0.44 umol NO3‐ (g FW)‐1 h‐1. This last value was low compared with that of other species, while KM is in the range for other higher plants. From the results of our experiments at low and high NO3‐ concentrations, we discuss the possibility of the existence of two NO3‐ uptake systems, one of a high affinity (functioning at low NO3‐concentrations) and another of low affinity (operative at high NO3‐ level in the medium). 相似文献
A greenhouse experiment with beans (Phaseolus vulgaris L.) was performed in order to investigate the effect of nitrogen and sulphur application and seed inoculation on the yield, leaf area, distribution of different nitrogen and sulphur fractions and N/S ratio in shoot, fruit and root.
Inoculation of plants together with nitrogen or sulphur application produces an increase in the concentration of total nitrogen and a decrease in the accumulation of nitrate‐nitrogen and sulphate‐sulphur in shoot, fruit and root. Leaf area increased more with nitrogen than with sulphur application while the highest amounts of fruit dry matter were obtained with sulphur application.
N: S ratios obtained were different according to the part of the plant tested. Sulphur fertilization decreased the N: S ratios in shoot, fruit and root. The data obtained indicate that and adequate N: S ratio can insure maximum production of yield. 相似文献
The effect of salinity on growth response, nitrogen (N) fixation and tissue mineral content was investigated for four legumes: faba bean (Vicia faba L), pea (Pisum sativum L), soybean (Glycine max L), and common bean (Phaseolus vulgaris L). Plants were grown in a vermiculite culture system supplied with a N‐free nutrient solution with the addition of 0, 50, and 100 mM NaCl. Plants were harvested at the beginning of the flowering period and the dry weights of shoots and roots and acetylene reduction activity (ARA) were evaluated at the same time plant tissues were analysed for N, potassium (K), calcium (Ca), magnesium (Mg), and sodium (Na) contents. The depressive effect of saline stress on ARA of nodules was directely related to the salt induced decline in dry weight and N content in shoots. Growth inhibition by NaCl treatments was greater for the pea than for other legumes, whereas the soybean was the most salt‐tolerant Saline stress also affected the N content in shoots and roots. In general the N content accumulated in the shoot and Na in the roots of the four legumes tested, while K accumulated both organs. The acquisition of other macronutrients differed according to the legume species. The legumes most sensitive were P. sativum and V. faba which accumulated Ca in shoot and Mg both in the shoot and the roots. On the contrary, in G. max and P. vulgaris, the two most salt tolerant legumes, accumulated Mg in the roots and Ca in both vegetative organs. Our results suggest a relationship between the salt‐tolerant range in legumes and the macronutrient accumulation in vegetative organs. 相似文献
The effects of the interaction between sodium chloride, nitrate, and concentrations on growth and internal ion content of faba bean (Vicia faba L.) plants were studied, to understand the relationship between the above parameters and salt tolerance. Increased salinity substantially reduced the dry weight of roots and shoots and increased the root/shoot biomass ratio. Additional nitrate‐N considerably moderated the salinity effects on these parameters. The promotive effects of nitrate‐N were more pronounced on shoot dry weight. These results suggest that an exogenous supply of nitrate‐N would improve the vegetative growth of V. faba plants by moderating the suppresive effects of salinity. The evolution of the root and shoot content in potassium (K), sodium (Na), magnesium (Mg), calcium (Ca), and nitrogen (N) was monitored during vegetative growth. A high correspondence between total N and Ca content was found. The acquisition of Ca and K in response to salt and nitrate was similar in shoots and roots, whereas Mg uptake showed notable differences in the two organs. In salt‐affected plants, the roots were found to be high in accumulated Na while the shoots exhibited the lowest Na concentration. Potassium accumulation was higher in the shoots. In this way, there was an antagonistic effect between Na and K uptake. Analyses of the nutrient contents in plant organs have provided a data base on salt‐tolerance mechanisms of V. faba plants. 相似文献
Nitrate reductase activity (NRA; EC 1.6.6.1) was measured in leaves, stems and roots of Pisum sativum cv. Lincoln supplied with different nitrate concentrations and inoculated with selected Rhizobium leguminosarum strains. As a control, noninoculated plants were grown in the same nutrient medium. NRA was determined by an in vivo‐nitrate assay. Although differences in tissue NRA were mainly related to nitrate concentration in the growing medium, nodulation much affected the NRA in the different plant organs, especially in root. An increased proportion of total plant NRA occurred in the leaves and stems as nitrate concentration was increased. Nitrate accumulation in leaves, stems and roots was correlated with the concentration of this ion in the nutrient solution. Nodulation also affects the nitrate accumulation in the different plant organs. 相似文献
Miscanthus × giganteus bark was subjected to mild fractionation with peroxyformic acid by a two stage process. A factorial experimental design was used to study and quantify the effect of the variables (formic acid concentration (80-90%), hydrogen peroxide concentration (0.2-0.4%), temperature of the first stage (60-80 °C), and treatment time of the second stage (60-120 min)) on the main parameters of fractionation: pulp yield, remaining lignin and total polysaccharides in pulp. The dependence of lignin precipitation rate on hydrogen peroxide concentration in liquor was also studied. Hydrogen peroxide concentrations inferior to 0.5% seems to be suitable to recover high percentages of lignin. The isolated lignin was analysed by 2D-HSQC, 13C- and 31P NMR spectroscopy, FTIR spectroscopy, size-exclusion chromatography and chemical analysis. The most important chemical modifications taken place in the lignin during the fractionation were identified: β-O-4′ cleavage and hydrolysis of LC-bond structures. The C9-formula was also determined: C9H6.81O2.90(OCH3)0.68(COOH)0.07(OHPh)0.38(OHAl)0.33. 相似文献