Comparison of adaptability to nitrogen source among vegetable crops 3. growth response and accumulation of ammonium nitrogen and nitrate nitrogen of root vegetables cultured in nutrient solution containing nitrate ammonium and nitrite as nitrogen sources
Ikeda, H.; Osawa, T.
Journal of the Japanese Society for Horticultural Science 49(4): 563-570
Potato, carrot, radish (Raphanus sativus L. radicula group), turnip and Japanese radish (R. sativus L. daikon group) were cultured in nutrient solution containing NO3, NO3 + NH4 (1:1), and NO2 as N sources. The experiment consisted of 2 levels of N concentration (2 meq/l designated as low-N and 12 meq/l as high-N) and solution pH 5 and pH 7. Plants were grown under each treatment for approximately 3 wk. All root vegetables fertilized with NO3 and NO3 + NH4 had healthy leaves and grew well under all treatment conditions. The growth of root (edible portion) was often considerably better under NO3 + NH4 than NO3 nutrition. When plants were supplied with NH4, the top growth of potato and carrot was relatively good and the NH4-N concentration in their leaves was low. The top growth of turnip and Japanese radish was extremely inhibited, with NH4 nutrition, and the NH4-N concentration in the leaves was high. The highest NH4-N concentration, however, was detected in leaves of radish which showed intermediate growth. The concentration of NH4-N in leaves of plants which showed markedly restricted growth in NH4 was a few times as much as the concentration of amide-N. Nitrite toxicities were more intensive under lower solution pH and higher N concentration. The concentration of NO3-N in leaves was scarcely affected by solution pH but was affected markedly by N forms and levels in nutrient solution.