Rapid and non-destructive measurement of nitrogen-status in ornamental cuttings by near-infrared-spectroscopy as part of a quality assessment system in supply chains of young plant production
D. Lohr, P. Tillmann, S. Zerche, U. Druege and E. Meinken
Book of Abstracts.International Conference on Quality Management in Supply Chains of Ornamentals. 21-24 February, 2012. Golden Tulip Sovereign Hotel, Bangkok, Thailand.
2012
บทคัดย่อ
Role of nitrogen in adventitious root formation of leafy cuttings is discussed extensively for different ornamental species. To date, this knowledge is rarely used for a quality assessment system in supply chains of young plant production. As analysis of growing media or nutrient solution during stock plant cultivation have limited significance and plant analysis e.g. Kjeldahl- or Dumas-N are too time consuming and expensive. In the present study1, we explored the potential of Near-Infrared-Spectroscopy (NIRS) as fast and non-destructive alternative. Cuttings of Pelargonium x hortorum, Pelargonium x peltatum and Chrysanthemum x grandiflorum from current production of three companies and from stock plants cultivated with different levels of N-supply at Weihenstephan research institute have been used for calibration. NIR-spectra were taken from intact, fresh cuttings using a Zeiss NIR-Diode-Array-Spectrometer fitted with a rotary plate for sample presentation. As reference, four N-fractions (amid-N, nitrate-N, amino-N, protein-N) and total-N were analysed using a modified Kjeldahl procedure. Additionally, sums of extractable N-fractions (enf-N=amid-N+nitrate-N+amino-N) and organic bounded N-fractions (onf-N=amid-N+amino-N+protein-N) were calculated. The dataset was 241 samples in total, thereof 161 were used for calibration and 80 samples build the validation set. Best prediction power was achieved for protein-N with a standard error of prediction (SEP) of 1.98 mg N∙g DM-1 and a R² of 0.89, for total-N (SEP = 2.91 mg N∙g DM-1; R² = 0.88) and for onf-N (SEP = 2.61 mg N∙g DM-1; R² = 0.87). Amid-N showed a poorer but acceptable accuracy with SEP = 0.40 mg N∙g DM-1 and R² = 0.70. For nitrate-N, amino-N and enf-N, prediction power was poorest with R² between 0.55 and 0.67. Results reveal that protein-N fraction, total-N and sum of organic bounded N-fractions can be predicted by NIRS non-destructively within a few seconds. This makes NIRS a promising tool for quality assessment of ornamental cuttings.