Effect of sulphuric acid scarification on seed accessions of cluster clover (Trifolium glomeratum) stored in a genebank
Martin, I.; Guerrero, M.
Seed Science and Technology 42(2): 293-299
Gene banks require operative germination protocols to monitor the seed viability of large numbers of samples. As dormancy imposed by impermeable seed coats (hardseededness) is very frequent in forage legume accessions, adequate scarification pre-treatments are needed to accurately evaluate seed viability. The effectiveness of scarification by immersion in sulphuric acid for different lengths of time (0, 15, 30, 60 and 90 minutes) was studied in two populations of T. glomeratum. Thirty minutes was found to be the optimal scarification time for these samples. This pre-treatment time was applied to 53 genebank accessions stored for ten years under long-term conservation conditions. The percentage of seeds that showed evidence of softening in these accessions ranged from 20 to 94% and the treatment was highly damaging in seven samples. In some cases, differences in the response to the sulphuric acid scarification treatment were found among seeds of the same accession. Variation in the effect of the scarification treatments between and within samples makes the routine use of potentially harmful procedures, such as acid scarification, difficult in gene bank seed viability monitoring.