## 3 Results and Discussion
### Analysis of Vegetative Indices  
In the case of the hyperspectral analysis conducted with the purple-leaved crops, some difficulties arise in the indices' calculation based on the light reflection in the spectrum green region. It is well-known that in the basil varieties with purple leaves, the anthocyanins are concentrated in the adaxial and abaxial epidermal cells in form of vacuolar solutions [31]. The anthocyanins can screen more than 90% of the green light giving protection to the mesophyll of the basil leaves from the photo-oxidative stress [32]. Figure 5 shows the reflection spectra of the purple and green leaves of the \"Markus\" basil variety. At a high anthocyanins concentration, the light absorption in the green part of the spectrum increases and so does the reflection in the near-infrared range. That is why it is impossible to identify the relationship between the PRI index and the stress states of the purple basil. So, in the future in order to assess the stress conditions, we used the vegetative indices associated with the photosynthetic pigment concentration. The main advantage of the spectral method based on the reflection spectra analysis for the assessment of the pigment content consists in the fact that it is possible to determine their concentrations both for the whole plant and for an individual leaf (Figures 6 and 7). Figure 5: Reflection spectra (**A**) and appearance (**B**) of purple and green basil leaves of “Markus” on 30 th day of cultivation. The analysis revealed the uneven distribution of the indices of R\({}_{750}\)/R\({}_{700}\) for chloroplasts and mARI for anthocyanins over the leaf area (Figures 6 and 7). Similar results were obtained for other indices under study (the data are not provided). This can be attributed to the varietal characteristics of the purple basil, which, depending on a variety, is characterized by instability of the purple pigments (anthocyanins) in both individual leaves and the whole plant [33]. Additionally, the uneven distribution of the index is affected by shadows due to uneven lighting and the glare of reflected light from the glossy surface of the leaf. To process the obtained hyperspectral images, the software \"Envi 5.2\" was used, the vegetative indices average values were obtained for whole plants on the 30 th day of cultivation. For analyzing, from images of individual leaves, several areas were selected not containing any glare and shadows; then the average index value for the selected areas was determined (Table 3). Figure 6: Graphic image of mARI index of basil leaves in false colors on 30 th day of cultivation. Figure 7: Graphic image of R\({}_{750}\)/R\({}_{700}\) index of basil leaves in false colors on 30 th day of cultivation. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Plant Variety** & **Sample Group** & **Index ARI** & **Index mARI** & **Index R\({}_{750}\)/R\({}_{700}\)** & **Index MND\({}_{705}\)** & **Index CRI\({}_{700}\)** \\ \hline \multirow{4}{*}{\"Red Ruby\"} & Control & 9.07 & 9.15 & 3.14 & 0.52 & 6.77 \\  & UV-A & 10.28 & 10.21 & 3.22 & 0.5 & 9.07 \\  & UV-B & 12.14 & 11.36 & 3.15 & 0.50 & 9,47 \\  & UV-C & 10.73 & 10.52 & 3.65 & 0.59 & 8.00 \\  & Control & 9.81 & 10.01 & 2.78 & 0.49 & 6.91 \\ \multirow{2}{*}{\"Gastronome\"} & UV-A & 12.13 & 11.71 & 3.59 & 0.55 & 8.97 \\  & UV-B & 9.21 & 8.73 & 4.16 & 0.59 & 7.94 \\  & UV-C & 11.87 & 11.84 & 3.39 & 0.55 & 9.13 \\ \multirow{2}{*}{\"Markus\"} & Control & 9.32 & 9.30 & 4.30 & 0.65 & 6.74 \\  & UV-A & 9.01 & 8.99 & 3.29 & 0.52 & 7.79 \\ \multirow{2}{*}{\"Markus\"} & UV-B & 9.48 & 9.32 & 3.81 & 0.57 & 6.84 \\  & UV-C & 10.16 & 10.23 & 4.48 & 0.61 & 6.92 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Average values of vegetative indices for basil varieties “Red Ruby”, “Gastronome” and “Markus” on 30 th day of cultivation.