Introducing inexpensive in vitro solid culture medium for producing high quality Phalaenopsis orchid plantlets

Orchids, especially Phalaenopsis orchids, are known as one of the most popular ornamental plants in the world markets. The use of in vitro cultivation system is the only way to produce these orchid plantlets. Producers of this plant have to buy and import it from foreign companies. Currently, increasing the costs of plantlet production and cultivation in the country, which requires the buy of imported chemicals for prepare in vitro culture media, has caused problems for domestic producers of this product. Therefore, making a suitable and low-cost culture medium to produce inexpensive and high-quality tissue culture seedlings on a commercial large scale was the main purpose for this study.

In this study, 5 mm protocorm explants were cultured in eight treatments of culture media (including 1/2 MS (control), FAST and six types of hand-made medium used of made in Iran inexpensive fertilizers with numbers one to six (M6 to M1) were named) and three replications in a completely randomized design. Explants were subcultured every 30 days and their total fresh weight was recorded. Also, three months after cultivation, some physiological traits (total fresh and dry weight, leaf and root dry weight), biochemical (concentration of photosynthetic pigments, anthocyanins and soluble, storage and total carbohydrates) and maximum efficiency of photosystem II were measured in plantlets.

The results showed that plants grown in different culture media in all traits had a significant difference at the level of 1% probability. The highest total fresh and dry weight, photosynthetic pigments and the maximum efficiency of photosystem II, occurred in M5 and M6 culture media and the lowest in M2. Also, M6 with 155.7 and 1/2 MS 40.2 mg g-1, respectively, had the highest and lowest total carbohydrate content. The highest (31.3 μmol g-1) and lowest (14.9 μmol g-1) anthocyanin content were observed in M2 and 1/2 MS culture media, respectively.

By adding banana powder and activated charcoal to M5 (300,000 Rials and 7.15 $) and M6 (440,000 Rials and 10.52 $) inexpensive culture media compared to orchid conventional culture media (1/2 MS and FAST) and reducing in vitro cultivation costs 23% and 12%, respectively, were selected as suitable low-cost solid culture media for growth and development of Phalaenopsis orchid plantlets, which according to the biomass partitioning curve can be introduced M6 as an inexpensive and suitable culture medium due to the production of more well-formed plants in comparison of all culture media.