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Near infrared spectroscopy or known as NIRS has been widely employed in many fields including agriculture, especially for sorting and grading of agricultural products. Spectra pre-processing is one of the main factors affecting model accuracy and prediction capabilities of NIRS. The objective of the present study was to study the impact of different spectra corrections namely mean centering (MC), mean normalization (MN), de-trending (DT), multiplicative scatter correction (MSC), standard normal variate (SNV) and orthogonal signal correction (OSC), to the prediction accuracy of quality parameters: titratable acidity (TA) and soluble solids content (SSC) in intact mango. A total of 91 mango samples (cv. Kent) were used as dataset for calibration and external prediction which was separated by means of systematic sampling based on a property (SSBP) approach. Diffuse reflectance spectra (log1/R) were acquired and recorded in wavelength range of 1000 – 2500 nm by Antaris Fourier transform NIR instrument. Judging from calibration and prediction performance, MSC found to be the best spectra pre-processing method prior to prediction model development with R2 prediction are 0.72 for TA and 0.76 for SSC. Although MSC increase the prediction performances based on R2, RMSE, RPD and RER metrics compared to the baseline, the achieved RPD, 1.9 for TA and 1.8 for SSC of this findings are still poor and need improvements to achieve even higher levels of accuracy and reliability necessitates for real-time applications.

Potassium (K) plays a crucial role in reducing the severity of drought stress. Potatoes are considered drought sensitive crops due to their shallow root system. In this study, potato cultivars ‘Milva’ and ‘Agria’ grown under -K (75 μM) and +K (1000 μM) supply in a hydroponic system were examined under greenhouse conditions. Half of the plants for each cultivar and K supply were treated for two weeks with polyethylene glycol (PEG) to induce osmotic stress at 67 days after planting (dap). For recovery, plants grew two more weeks without PEG. Plant height, biomass, and water consumption were measured weekly. Leaflets were analysed before, during, and after PEG addition to subsequently determine parameters, for example, total free amino acids and metabolites. Additionally, the K allocation in plant parts was determined. K supply and PEG positively affected biomass production, and the production of side shoots was enhanced with -K and PEG. The water consumption increased with PEG addition in Milva, which was not observed in Agria. K and sugars accumulated in side shoots, showing cultivar and treatments specific reactions. Individual amino acids, including isoleucine, leucine, valine, and alanine, accumulated under low K supply and PEG-induced osmotic stress, and functional characterization could provide information on the response to drought stress. However, K remained an important variable, providing functions of other osmolytes to maintain plant metabolism. The results revealed morphophysiological and biochemical indications for adaption mechanisms against osmotic stress and may help to identify drought stress tolerant cultivars.