Effect of Phosphorus on Nitrate in Sugar Beet (Beta vulgaris L.)

Culture‐solution and field experiments indicate that P‐deficient sugar beets, particularly young plants, do not take up nitrate as well as plants adequately supplied with P. The increase in concentration of NO3‐N in whole tops of young seedlings, cotyledons, or petioles of first true leaves with increased P supply is greater than can be accounted for by a concomitant decrease in percent dry‐matter of these plant parts. The decreased absorption of NO3 by P‐deficient plants in aerated culture‐solution, with all roots exposed continuously to high concentrations of NO3 indicates that the phenomenon reflects not merely increased root extension but a physiological aberration brought about by P‐deficiency.