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.
Determination of Critical Nitrogen Dilution Curve Based on Stem Dry Matter in Rice
Plant analysis is a very promising diagnostic tool for assessment of crop nitrogen (N) requirements in perspectives of cost effective and environment friendly agriculture. Diagnosing N nutritional status of rice crop through plant analysis will give insights into optimizing N requirements of future crops. The present study was aimed to develop a new methodology for determining the critical nitrogen (Nc) dilution curve based on stem dry matter (SDM) and to assess its suitability to estimate the level of N nutrition for rice (Oryza sativa L.) in east China. Three field experiments with varied N rates (0–360 kg N ha−1) using three Japonica rice hybrids, Lingxiangyou-18, Wuxiangjing-14 and Wuyunjing were conducted in Jiangsu province of east China. SDM and stem N concentration (SNC) were determined during vegetative stage for growth analysis. A Nc dilution curve based on SDM was described by the equation (Nc = 2.17W−0.27with W being SDM in t ha−1), when SDM ranged from 0.88 to 7.94 t ha−1. However, for SDM < 0.88 t ha−1, the constant critical value Nc = 1.76% SDM was applied. The curve was dually validated for N-limiting and non-N-limiting growth conditions. The N nutrition index (NNI) and accumulated N deficit (Nand) of stem ranged from 0.57 to 1.06 and 51.1 to −7.07 kg N ha−1, respectively, during key growth stages under varied N rates in 2010 and 2011. The values of ΔN derived from either NNI or Nand could be used as references for N dressing management during rice growth. Our results demonstrated that the present curve well differentiated the conditions of limiting and non-limiting N nutrition in rice crop. The SDM based Nc dilution curve can be adopted as an alternate and novel approach for evaluating plant N status to support N fertilization decision during the vegetative growth of Japonica rice in east China.
Alicyclic Analogue of Mescaline
WE wish to describe the preliminary pharmacology of a mescaline analogue, 2-(3,4,5-trimethoxyphenyl)-cyclopropylamine (TMT, II). This compound was selected for synthesis as a potential long-acting psychotomimetic which would be useful for studying the mode of action of mescaline-like compounds.