Varietal specificity in growth, nitrogen uptake, and distribution under contrasting forms of nitrogen supply in spinach
1998
Zornoza, P. | Gonzalez, M.
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 NH4 detoxification in the roots and partly to the form in which the N is retained or transported to the shoot.
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