Temperature conditions optimization for storing tropical orchid seeds on the example of Eulophia streptopetala and Stanhopea tigrina

The paper presents the results of the study of temperature regime optimization for storing seeds of tropical orchids on the example of Eulophia streptopetala Lindley and Stanhopea tigrina Batem ex Lindl. Mature seeds were frozen at temperatures of −18°C, −40°C or −80°C for a period of 1, 3, 6 or 12 months, the storage temperature was +4°C. Before and after freezing, the viability of seeds was determined by visual and tetrazole methods. After defrosting, the seeds were sown and the plants grown from them were cultivated on a nutrient asymmetric medium, then the dynamics of plant development was recorded, the content of photosynthesis pigments (chlorophyll and carotenoids) was quantified. The analysis of the data obtained showed that the viability of seeds significantly decreases after storage, including in conditions of low temperatures. At the same time, in experimental groups of plants, the terms of early ontogenetic states were shortened, and the growth rate of protocorms increased. Freezing of seeds caused further restructuring of the photosynthetic apparatus. The optimal temperatures for storing seeds of the species Eulophia streptopetala were +4°C, and for Stanhopea tigrina −80°C and −40°C.