Physiologia Plantarum · 1983 · 23 citations · 27 references
AgriculturePlant BiologyPlant SciencesPhysiological EcologyPlant NutritionPlant PhysiologyNitrogen AssimilationNutrient AssimilationNutrient AvailabilityNutrient Uptake By PlantsPlant GrowthPlant Nutrient UptakeBiomass Accumulation RatesGrowth RatesLeaf Nitrogen AssimilationNitrogen Uptake DynamicsPlant Growth AnalysisPlant Nitrogen UptakePlant-available NitrogenSequential Culture Systems
Relationships among growth, N accumulation and assimilation were investigated in Chrysanthemum morifolium Ramat cv. Fiesta in experiments testing the effects of varying levels of NO –3 3 supply and of increasing NH + 4 added to a constant level of NO –3 3 Flowing solution culture systems were used to provide NO − 3 at concentrations of 0.03 to 5.0 mol m –3 and NH + 4 levels from 0.05 to 0.3 mmol m –3 added to 0.1 mol m –3 NO − 3 . Rates of growth, N absorption, accumulation, distribution and utilization were estimated by regression analysis of data obtained from sequential plant harvests, and rates of NO − 3 and NH − 4 net uptake were estimated from solution depletion. A sustained ambient NO − 3 concentration of 0.03 mol m –3 was evidently adequate to support growth, since relative growth rates were not affected by increasing NO − 3 supply from 0.03 to 1.0 mol m –3 , nor from 0.25 to 5.0 mol m –3 , in separate experiments. Shoot growth rates were stimulated by NH 4 added to NO − 3 one experiment, but not when the experiment was repeated under ambient conditions less favorable to growth. Relative accumulation rates for total N increased with increasing NO − 3 and with NH + 4 added to NO − 3 A constant proportion of NO − 3 taken up was reduced when NO − 3 alone was supplied. Both the proportion of total N taken up as NO − 3 and the proportion of NO − 3 reduced decreased with increasing NH + 3 added to NO − 3 NH + 4 uptake apparently must exceed a threshold of about 30% of the total uptake to inhibit NO − 3 uptake. Utilization of N in chrysanthemum was apparently limited by redistribution since relative accumulation rates for total N were equal to or greater than relative growth rates, in contrast to results reported for several other species. Results of this study and other information support the postulate that NH + 4 added to NO − 3 might stimulate growth by increasing transport of reduced N from roots to shoots, thus increasing the supply of reduced N available to support growth of shoot meristems.
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Modified Reagents for Determination of Urea and Ammonia
Albert L. Chaney, Edward P Marbach · Clinical Chemistry · 1962 · 3.9K citations
Photosynthesis and productivity in different environments
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