THE EFFECT OF FOLIAR FERTILIZATION OF FRENCH BEAN WITH IRON SALTS AND UREA ON SOME PHYSIOLOGICAL PROCESSES IN PLANTS RELATIVE TO IRON UPTAKE AND TRANSLOCATION IN LEAVES

Iron chlorosis is a wide-spread limiting factor of production in agriculture. Fe deficiencies is done mainly by foliar sprays because soil application generally are ineffective, especially for annual crops. A pot experiment, conducted in a phytotron, investigated the effectiveness of foliar fertilization of French bean with 3 inorganic iron salts [FeSO4 · 7H2O, FeCl3 · 6H2O, Fe(NO3)3 · 9H2O] and 2 organic iron salts [Fe-Citr., Fe-EDTA], applied with and without the addition of 0.5% CO(NH2)2. Iron was applied 3 times only on simple leaves in the form of aqueous solutions containing 0.2 mg Fe in 1 cm3, compared to water as the control treatment. The obtained results show that the application of iron salt solutions resulted in a distinct increase of Fe content in simple leaves and in the next trifoliate leaves. Foliar fertilization of the plants with Fe(NO3)3 was the most effective, while feeding with Fe-EDTA was the least effective. Iron given in the form of chelates showed greater mobility in the plants than that applied in the form of inorganic salts. Foliar fertilization of the plants with inorganic iron salts significantly increasedchlorophyll a+b and carotenoid content in the leaves as well as their stomatal conductance and the photosynthesis and transpiration rates. But the impact of Fe chelates, in particular Fe-EDTA, on the abovementioned plant traits was not clear. The leaves of the plants treated with Fe(NO3)3 showed the highest content of photosynthetic pigments and the most intense gas exchange. The application of inorganic iron salts and Fe-Citr. resulted in a significant increase in the number of nodules formed on the bean roots and their weight. The plants treated with Fe-Citr. produced the largest number of nodules, while those treated with Fe(NO3)3 developed nodules with the highest weight. The addition of urea to the iron solutions had an effect on the increase in the value of the iron transport rate and on the decrease in iron and carotenoid content, the leaf gas exchange rate as well as the number of root nodules and their weight.