## 3 Results and Discussion
### Biometric Measurements of the Stevia Plants
\begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline \multirow{2}{*}{**Treatment**} & \multicolumn{2}{c}{**Dry Mass**} & \multicolumn{2}{c}{**Redeione Sugars**} & \multicolumn{2}{c}{**Phenolic Compounds**} & \multicolumn{2}{c}{**Ascorbic Acid**} \\  & \multicolumn{2}{c}{**[\%]**} & \multicolumn{2}{c}{**[\%]**} & \multicolumn{2}{c}{**[\%]**} & \multicolumn{2}{c}{**[\%]**} & \multicolumn{2}{c}{**[\%]**} & \multicolumn{2}{c}{**[\%]**} \\  & **Joly 1** & **September** & **Joly** & **September** & **July** & **September** & **July** & **September** \\ \hline
0 W & 23.14 \(\pm\) 2.59 a & 30.47 \(\pm\) 2.99 a & 0.76 \(\pm\) 0.62 a & 1.74 \(\pm\) 0.60 a & 270.26 \(\pm\) 15.83 a & 337.88 \(\pm\) 31.88 a & 139.99 \(\pm\) 7.79 a & 143.30 \(\pm\) 7.21 a \\ NR & 24.75 \(\pm\) 2.28 a & 27.87 \(\pm\) 0.99 bc & 0.77 \(\pm\) 0.46 a & 1.99 \(\pm\) 0.80 a & 229.73 \(\pm\) 33.01 ab & 241.03 \(\pm\) 21.29 b & 133.14 \(\pm\) 24.24 b & 124.66 \(\pm\) 14.27 c \\
1 W & 24.13 \(\pm\) 2.51 a & 28.82 \(\pm\) 1.99 ab & 0.82 \(\pm\) 0.48 a & 2.27 \(\pm\) 0.25 a & 185.62 \(\pm\) 15.35 b & 260.57 \(\pm\) 24.18 b & 121.02 \(\pm\) 5.12 b & 132.38 \(\pm\) 10.07 bc \\
2 W & 23.73 \(\pm\) 2.54 a & 26.52 \(\pm\) 0.56 c & 0.93 \(\pm\) 0.71 a & 1.95 \(\pm\) 0.23 a & 216.80 \(\pm\) 21.94 b & 246.46 \(\pm\) 19.90 b & 128.62 \(\pm\) 7.22 ab & 135.42 \(\pm\) 6.15 ab \\ \hline \hline \end{tabular}  
* Values are expressed as the mean (n = 9) \(\pm\) standard deviation. Mean values with different letters within the same column are significantly different (\(\alpha\) = 0.05) according to Duncan’s test; 0 W—not irrigated, 1 W—irrigated once a week, 2 W—irrigated two times a week, NR—irrigated only during the dry periods (no rainfall).  
\end{table} 
Table 4: Influence of irrigation on dry mass content and concentration of reducing sugars, phenolic compounds and ascorbic acid in leaves of stevia measured in the years 2014-2016. Figure 2: Influence of irrigation on biometric characteristics of stevia plants measured in the years 2014–2016. n = 36; 0 W—not irrigated, 1 W—irrigated once a week, 2 W—irrigated two times a week, NR—irrigated only during the dry periods (no rainfall). Different letters (a, b) within one parameter indicate significantly different values according to [PERSON]’s test. groups in the average dry mass content in stevia leaves in September. Sample 0 W and 1 W were characterised with the highest concentration of dry mass in September and sample 2 W was characterised with the lowest, so it is not easy to determine whether a greater addition of water can always reduce dry mass content in the stevia leaves. A study by [PERSON] et al. (2015) about drought stress on the _Stevia reaudiana_ properties has shown different results: stevia plants grown in worse drought conditions were characterised with lower dry weight content [27]. In the study by [PERSON] et al. [22], the impact of different irrigation methods was more clear-cut. Stevia plants that were irrigated more often were characterised with lower dry mass content in contrast to stevia plants that were irrigated less often. However, in the study of [PERSON] et al. [24] in which stevia plants were grown under water stress, leaves of plants that received a smaller quantity of water were characterised with lower dry mass content than leaves of the stevia plants that acquired a greater amount of water. Different irrigation practices did not have an influence on the concentration of reducing sugars in stevia leaves, which were, in July, in the range from 0.76 for 0 W to 0.93% for 2 W and, in September, in the range from 1.74 for 0 W to 2.27% for 1 W. In the study of [PERSON] et al. [28], stevia plants grown with an inadequate water level (water deficiency) were characterised with a higher concentration of glucose and saccharose in stevia leaves. Studies conducted in Iran showed that the irrigation of stevia cultivated in fields as well as in greenhouses can result in an almost 20% increased concentration of sugars in the stevia plants [29].