## 2 Results and Discussion
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{\
\begin{tabular}{c} **Date of Seed Potaces** \\ **Planting to Soil** \\ \end{tabular} } & \multirow{2}{*}{
\begin{tabular}{c} **Plyopathogens inoculated to** \\ **Seed Potatoes** \\ \end{tabular} } & \multicolumn{2}{c}{**Yield of Bulbs from One Plant (g)**} & \multicolumn{2}{c}{**Yield of Stems from One Plant (g)**} \\ \cline{3-6}  & & **Fresh Mass (g)** & **Dry Mass (g)** & **Fresh Mass (g)** & **Dry Mass (g)** \\ \hline \multirow{4}{*}{10.03} & Control & 494.7 b  & 84.6 b  & 53.5 c  & 29.3 b  \\  & _Fusarium oxysporum_ & 484.1 a  & 82.4 a  & 49.9 a  & 27.3 a  \\  & _Pectobacterium corotovorum_ & 485.4 b  & 84.2 b  & 51.9 b  & 28.5 b  \\  & _R Rhizectonia solani_ & 484.8 ab  & 83.3 ab  & 51.8 b  & 28.4 b  \\  & _Control_ & 505.9 d  & 86.8 e  & 59.9 e  & 32.2 e  \\  & _Fusarium oxysporum_ & 484.5 b  & 83.3 ab  & 53.6 c  & 29.3 b  \\  & _Pectobacterium corotovorum_ & 495.7 c  & 85.2 c  & 55.4 d  & 30.4 d  \\  & _Rhizectonia solani_ & 495.4 c  & 85.1 c  & 55.2 d  & 30.3 d  \\  & Control & 517.3 e  & 88.6 f  & 67.1 b  & 37.2 b  \\
10.05 & _Fusarium oxysporum_ & 494.6 b  & 84.9 b  & 63.0 f  & 34.8 f  \\  & _Pectobacterium corotovorum_ & 506.7 d  & 86.6 d  & 35.9 g  \\  & _Rhizectonia solani_ & 506.0 d  & 86.5 d  & 64.6 f  & 36.0 g  \\  & LSD\({}_{0.05}\) & 10.0 & 1.8 & 1.5 & 1.0 \\ \hline \hline \end{tabular}  
* Means marked with the same letters do not differ statistically at the significance level \(p=0.05\). LSD was calculated at the significance level of \(p=0.05\).  
\end{table} 
Table 4: Fresh and dry weight of tubers and dried stems per plant, obtained from the seed potatoes stored at 4 \({}^{\circ}\)C from harvest until inoculation with phytopathogens on 10 February and then at 15 \({}^{\circ}\)C and 80% RH before planting in the soil on 10 March, 10 April, and 10 May. planted in the ground on 10 May, three months after inoculation. A detailed understanding of this issue needs further research. Stem growth kinetics as a marker of the quality of seed potatoes infested with phytopathogens was also useful. However, the negative effect of phytopathogens inoculated into seed potatoes and the emitting volatile compounds on stem growth and quality was less spectacular than in the case of root development; although, in most experimental variants there was a trend or statistically proven evidence of an adverse effect of these microorganisms on the development of above-ground plant organs. The used markers showed that the tested phytopathogens inoculated into seed potatoes also influenced, to a different extent, the intensity of gas exchange (net photosynthesis, transpiration, stomatal conductivity, and intercellular CO\({}_{2}\) content), index of chlorophyll content, tuber and stem yield, and the quality of foliage measured on a five-point valuation scale. These parameters may serve as useful markers of the quality of seed potatoes infected with phytopathogens; although, their evaluation requires a longer plant cultivation period than in the case of root growth kinetics. All the used markers showed that unfavorable effects of phytopathogens were relatively the smallest in the case of plants obtained from seed potatoes less colonized by fungi and planted in the ground on 10 March, i.e., 30 days after inoculation. They were more evident in the case of plants obtained from seed potatoes that were sprouted two months after inoculation and planted into the ground on 10 April, and even greater when they were planted on 10 March, three months after inoculation. This indicates that a longer period from the inoculation of phytopathogens until the seed potatoes planting had a more negative effect on plant development. In the shorter time, these pathogens probably only slightly developed, which resulted in their less negative impact on plant development.