## 2 Materials and Methods
### Cost Analysis  
The commercial plant tissue culture company, 'Plant Research Laboratories' located in KEN 98 Ave, Warsaw, Poland was used for cost analysis data. Three following variable costs were considered: reagents and containers, labor costs, along with electricity consumption, and plant growth in a 'growth room'. Due to variable VAT rates across the world, all prices are net prices. Most of the reagents essential for the preparation of the medium were purchased from Duchefa Biochemie (A. Hofmanweg 71, Haarlem, the Netherlands). The wholesale price of 100l MS medium is $55.19, 25 kg of plant agar costs $2116.55, and 25 g of BAP costs $121.76. As the source of carbon, sugar was used as a cheap replacement for highly purified sucrose. The cost of 1 kg of 'Diamant' (PFEIFER & LANGEN S.A., Poznan, 60-837, Poland) sucrose is $0.51. Wholesale prices are listed in Table 2. Because of the subtle differences in some cost prices, values are given in a thousandth part and are marked with an asterisk. Fixed costs, including the laboratory building and equipment were ignored in this study because of differences between equipment used in other laboratories and a lack of possibility for comparison. Other costs that needed to be considered in plant production were electricity costs, which were $0.14 per kilowatt-hour, labor costs (man-hour) which was $3.18, and a 350 mL container, which cost $0.07. To determine how many containers with plants can be produced in one hour, the number of explants cut out during five hours of work by two employees, calculated over four repeating cycles was calculated in order to obtain an average. Power consumption of the laminar flow chamber is 49 W (0.049 kW). The cost of work necessary to produce one container with plants was calculated by dividing a man-hour salary by the number of containers produced within one hour. The cost of electricity consumption, necessary to produce one container with plants, was calculated by multiplying the electricity consumption (of the laminar flow chamber) by the cost of 1 kilowatt-hour, and divided by the mean number of containers produced during one hour. The cost of labor and electricity for the production of a single plant was the cost of production of one container with plants, divided by the number of explants in the container. The 'growing room' is equipped with racks 5 shelves. The dimensions of a shelf are \(140\times 60\) cm which gives 0.84 m\({}^{2}\). Each shelf is illuminated with one 36 W (0.036 kW), cool white fluorescent tube. There can be 55 containers with 10 explants placed on each shelf. The price of growing the plants for 4 weeks was calculated using the formula:  
\[PGC=\left(\frac{EC\times PH\times DM}{NC}\times kWh\right)/N \tag{1}\] \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Ingredients for Medium** & **Wholesale Prices of** & **Ingredients for 1 L of** & **Costs of Ingredients for** \\
**Preparation** & **Ingredients (in5)** & **Medium Preparation** & **1 L of Medium** \\ \hline MS medium Duchefa 100 L & 55.19 & MS medium Duchefa (0.5 L) & 0.27 \\ Sucrose (food sugar) 1 kg (1000 g) & 0.51 & Sucrose (20 g) & 0.01 \\ Agar Duchefa 25 kg (25,000 g) & 2116.55 & Agar Duchefa (7 g) & 0.59 \\ BAP Duchefa 25 g (25,000 mg) & 121.76 & BAP Duchefa (0.5 mg) & 0.002* \\ \hline \hline \end{tabular}  
* Total cost per 1 liter of MS2 medium
* Source: data from Plant Research Laboratories.  
\end{table} 
Table 2: Wholesale prices and costs of reagents used in _P. tomentosa \(\times\) P. fortunei_ plants production and reagents necessary for MS2 production. where:  
PGC--plant growth cost  
EC--electricity consumption per one shelf  
PH--photoperiod length  
DM--mean number of days in month--30.5  
NC--number of containers on one shelf  
kWh--cost of 1 kWh  
N--number of explants  
Each container is filled with 0.083 mL of MS2 medium, 1 L of medium is enough to fill 12 containers.