2.4. 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., Poznań, 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 × 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:
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. The cost of one container with the medium was calculated by dividing the total cost of 1 L MS2 medium by the number of 12 containers plus the price of a single container.
Other costs, such as time for the preparation of the medium, transporting containers from the laminar chamber room to the growing room or power consumption for autoclaving are specified as economic overheads, and these account for an additional 20% of the total cost of one container with 10 explant production costs. Rooting costs were calculated in the same way as plant multiplication, considering the MS4 medium. Additionally, the final cost was increased by the percentage of unrooted shoots. The cost of acclimatization was not given to us by the Plant Research Laboratories.
The gross margin of variable costs in this research was calculated over the value of production, according to Elum et al. [
12]. Gross margin was calculated using the following formula:
where:
GM—gross margin expressed as a percentage
TR—total revenue in $
TVC—total variable costs in $
The Gross margin model is a great tool used to investigate the initial assessment of production. As a result, the Plant Research Laboratories suggested that the price of a single plant sold in agar is $0.4.