Theoretical Determination of a Critical Nitrogen Dilution Curve Based on the Carrot Case Study
The objectives of the present study were to: (a) formulate a general dilution equation for a critical nitrogen percentage in a leaf (Nc); (b) monitor dilution function of carrot as a case study; (c) demonstrate applicability of digital color imaging to monitor total nitrogen (Ntot) in crops. Carrot (Daucus carota) was grown on loess soil at five Ntot application rates. Ntot weight (kg/ha) was obtained by standard laboratory analysis and by image processing. Total yield of the treatments was the sum of canopy and roots dry matter. A new logistic decay curve Nc = a/[1 + (W/W0)b] agreed with experimental data. Nc (g/kg) is the critical nitrogen level, a and b are coefficients, and W/W0 is the relative dry matter biomass. Values of Nitrogen Nutrition Index (NNI) ≥ 1.0 indicated that there was no nitrogen deficiency in treatment larger than 100% application of Ntot. The weight of nitrogen in form of multiplication of the dry leaves weight (W) and N percent is suitable for the determination of nitrogen status. The availability of image-based data for N percent is faster, timely and less expensive than that of laboratory test. Applicability of digital color camera to monitor Ntot in crops instead of laboratory test was successfully demonstrated.
Nitrogen management of vegetable crops
N fertilization is often viewed as a cheap insurance against yield loss in vegetable production because of the generally large added value, resulting in application of fertilizer N often in excess of actual crop demand. In combination with the low fertilizer N recovery by many vegetable crops and the often excessive irrigation, this may lead to both health and environmental risks related to high nitrate concentrations in water leaving the root zone. In this review, we discuss the decisive factors in the overall N balance of field vegetable production systems and the different tools at hand to increase fertilizer use efficiency and consequently reduce N losses to the environment. Based on this, we identify areas of research and technology transfer where further work is required. Only an integration of the different methods and strategies for N management may really mitigate the risk of nitrate leaching and maintain crop yields while enhancing the environmental sustainability of vegetable production systems.
Metabolism of individual fatty acids by sheep depot adipose tissue in vivo and in vitro.
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1. Sheep adipose tissue and plasma have high stearate and low unsaturated fatty acid content compared to rat, dog and man. 
 
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2. In control animals in vivo uptake as well as release of various fatty acids by adipose tissue could be demonstrated. In vitro net release occurred. Fasting resulted in a decrease in tissue stearate and increased release of fatty acids. Adrenaline and noradrenaline had minimal lipolytic effect in vivo and in vitro. 
 
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3. Variations in the turnover rate of individual fatty acids were observed.