The Effect of Foliar Nutrition with Nitrogen, Molybdenum, Sucrose and Benzyladenine on the Nitrogen Metabolism in Carrot Plants

The Kazan F₁ carrot was cultivated in years 2004-2005 in open-work containers sized 60×40×20 cm filled in with silt loam and located on the open field under shade providing fabric. The following combinations of experiments were arranged: (1) control - without foliar nutrition, and foliar nutrition with: (2) urea, (3) solution of urea+Mo, (4) urea+Mo+BA (benzyladenine - BA), (5) urea+Mo+BA+sucrose, (6) BA in the concentration of 5 mg·dm^-3 and (7) BA in the concentration of 10 mg·dm^-3. In combinations 2-5 the following concentrations of components in solution were applied: urea and sucrose each in 20 g·dm^-3, molybdenum 1 mg·dm^-3, benzyladenine 5 mg·dm^-3. Foliar nutrition was applied three times. In leaves sprayed with urea and with solution of urea+Mo as well as urea+Mo+BA, an increased concentration of NO₃^- was observed when compared to other sites. Foliar nutrition did not result in any significant changes in content of N-total and dry weight in leaves. Foliar application of urea, as well as the solution of urea+Mo+BA, caused an increase in the activity of nitrate reductase (NR) in leaves when compared to the control. Whereas, after spraying the plants with BA only, a noticeable decline in NR activity was revealed in comparison with the control; interestingly, a higher concentration of BA (10 mg·dm^-3) was more effective. Foliar nutrition with urea+Mo+BA+sucrose and spraying with benzyladenine only (independently from the concentration) resulted in a significant decrease of the content of NO₃^- in storage roots when compared to other combinations. The highest level of nitrogen uptake by single storage root and leaves of one carrot plant was found after urea+Mo+BA+sucrose nutrition. In case of N uptake by yield of leaves and biological yield of whole carrot plants (roots+leaves) the highest values were observed in combination no. 6.