Effect of EI-treatment in relation to physiological and biochemical traits in rice: delay in germination and its recovery with provision of glucose

Rice seeds treated with 0·2–1·2 v/v % of ethyleneimine (EI) demonstrated increasingly delayed germination concomitant with increasing dose. At the time of germination, the release of storage products was slightly inhibited at lower doses and completely reduced at higher doses. With increasing time after germination the development of shoot length, content of reducing sugar and free amino acid, and synthesis of nucleic acid and protein in treated seeds, showed the same response pattern as the control, although at reduced levels in the treated seeds. Consequently, it is interpreted that the delay of germination is due to physiological dormancy, i.e. impaired release of dormancy which would normally yield active forms of enzymes.

When treated seeds were cultured in [¹⁴C]-glucose medium, the specific activity of [¹⁴C]-glucose was higher in late-germinating seeds than in early-germinating seeds. Furthermore, the provision of glucose prevented the delay of germination, resulting in about a 10% increase in germination rate (survival rate), and yet had no effect on subsequent growth.

Finally, it is concluded that the damage resulting in delayed germination and reduction of survival differs from the damage leading to inhibition of subsequent growth in that the former can be compensated for by provision of glucose while the latter cannot.