Sulfuric acid treatments and their effect on embryo viability in raspberry seeds

The dynamism in the cultivar replacement in raspberry, has motivated the implementation of genetic improvement programs, both public and private. Seed germination is a fundamental process for genetic improvement, which has not yet been properly resolved. In species of the Rubus genus, germination is slow and low germination percentages are normally obtained because the seeds have a hard endocarp, and the embryo is characterized by having a period of dormancy. The protocols for the germination of seeds are based on scarification with concentrated sulfuric acid, which allows the endocarp to soften, and then, a period of stratification at low temperatures (4°C) to stimulate the dormancy output of the embryo. We evaluated the efficiency of sulfuric acid treatments and their effect on viability of the embryo by submerging raspberry seeds for 30 min in different solutions: control, sulfuric acid, sulfuric acid + calcium hydroxide and sulfuric acid + calcium hydroxide + sodium hypochlorite. Then the viability of the embryos was evaluated and then cold was applied for each treatment, with different periods: 0, 3, 4 and 5 months, to determine the interaction between both factors. The results indicate that there was no interaction between the factors and that only the use of acid had an effect on germination and did not affect the viability of the embryo. The main effect is observed in the time of beginning of germination concentrating it in a smaller period of time regarding control. We observed that the highest percentage of germination is obtained within the first three months from the establishment, unlike the control treatment where the beginning of germination is much slower, needing a much greater period to reach the same percentage than in acid treatments.