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  • Author or Editor: James W. Boodley x
  • Journal of the American Society for Horticultural Science x
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Abstract

‘Forever Yours’ roses (Rosa Hybrid Tea) were grown in recirculating nutrient solutions at 1.0 and 10.0 meq/liter K in combination with 10.0 meq/liter NO3-N or NH4-N. Low K limited the growth and flower production, regardless of N form. Ammonium-N fertilized plants showed NH4-N toxicity symptoms as interveinal chlorosis of the lower leaflets. An increased K supply reduced NH4-N toxicity symptoms. Concentrations of Ca and Mg were lower, while P was higher, in the tissue of NH4-N fertilized plants, as compared to NO3-N fertilized plants. Total N, alcohol insoluble N, soluble organic N, and NH4-N were higher in the tissue of plants which received NH4-N, as compared to NO3-N, regardless of K level. An increased K supply from 1.0 to 10.0 meq/liter resulted in higher NO3-N in NO3-N fertilized plants and lower NH4-N in NH4-N fertilized plants.

Open Access

Abstract

Rooted cuttings of Chrysanthemum × morifolium Ramat. ‘Gt. #4 Indianapolis White’ were grown in a greenhouse in a sand culture and supplied with either 3.75 or 15.0 mm NO 3 . Changes in dry matter, reduced N and NO 3 of the leaves, stems (plus petioles), roots, and inflorescence and in vivo NO 3 reductase activity (NRA) of leaves were determined at various stages of development. A decrease in the NO 3 supply caused a decrease in the accumulation of plant dry matter, reduced N and NO 3 . Plants receiving 3.75 mm NO 3 remobilized a significant amount of reduced N from vegetative tissues during inflorescence development, suggesting that newly absorbed N was inadequate to supply the flower. At both NO 3 fertilization levels, the NO 3 content of the leaves and stems declined during inflorescence development, suggesting an increased dependence on previously accumulated NO 3 for reduction. The highest NRA of the leaves (3.4 μmoles NO2 gFW−1 hr−1) was associated with early vegetative growth. NRA, however, was detectable throughout plant development. Nitrate reductase activity was greater at 15 mM NO 3 than at 3.75 mM NO 3 during vegetative growth and visible bud stages, but not at later stages of growth.

Open Access