Varietal specificity in growth, nitrogen uptake, and distribution under contrasting forms of nitrogen supply in spinach¹

In recognition of the late Prof. O. Carpena's contribution to the development of this research.

Abstract

Variations in nutrient uptake, growth and nitrogen (N) distribution under contrasting forms of N supply were studied in three spinach cultivars. The varieties (Viroflay, Butterflay, and Giant) were smooth, curly, and semi‐curly leaved, respectively. The plants were grown hydroponically with two nitrate‐.ammonium (NO₃:NH₄) ratios (100:0 and 80:20). Giant grown with both N forms displayed an increase of total N and potassium (K) absorption compared with that of those grown with NO₃ alone, by growing more and having tissues with greater capacity for NH₄ detoxification, i.e., they made better use of N supplied as NO₃ plus NH₄. Mixed N nutrition in Butterflay caused the nutrient uptake to be reduced strongly and lower plant growth, the root being unable to assimilate NH₄. Irrespective of the NO₃:NH₄ ratio supplied to Viroflay, the uptake of K, calcium (Ca), and magnesium (Mg) did not vary, but NO₃ uptake, growth, and N distribution were negatively affected by the presence of NH₄. Finally, the results obtained suggest that potentially useful specificity exists among these spinach cultivars for N form preference and for tolerance of NH₄. This may partly be due to their genetic ability of NH, detoxification in the roots and partly to the form in which the N is retained or transported to the shoot.

Notes

In recognition of the late Prof. O. Carpena's contribution to the development of this research.

Corresponding author (e‐mail address: [email protected]).