Influence of long term storage on plant growth substance levels, germination and seedling growth in legume seeds stored for 37 years

The present work describes the changes that take place in plant growth substance (PGS) levels, germination and seedling growth during germination of seeds of Medicago sativa cv. Clover, Trifolium repens cv. Milka and Trifolium pratense cv. Bora which had been stored for 37 years. The endogenous abscisic acid (ABA), indole-3-acetic acid (IAA), gibberellic acid (GA₃) and zeatin (Z) in the seeds were extracted and finally purified by high performance liquid chromatography (HPLC). Per cent germination, seedling height and the PGS levels in the germinating seeds were determined for 5 days at 23°C. On day 5, the per cent germination values of aged seeds of M. sativa, T. repens and T. pratense were 37%, 30% and 17%, respectively. The height of seedlings derived from the stored seeds was also significantly low, compared to that of controls. ABA level was high, throughout germination, in the aged seeds studied, but the levels of IAA, GA₃ and Z were low. Based on these results, it can be proposed that the reduced capability of germination and seedling vigour and growth in the aged seeds may be due to high ABA level which remained so throughout germination. This was also associated with decreased levels of GA₃, IAA and Z.