Physiological and biochemical aspects of pre-sowing seed treatments in fine rice (Oryza sativa L.)

The effects of pre-sowing seed treatments on the germination and emergence of fine rice and on reducing, non-reducing and total sugars and α-amylase activity were studied. Fine rice seeds were either soaked in tap water by a traditional method, hardened for 18 or 24 h (two cycles) or osmoconditioned (-1.1 MPa KNO₃) for 24 or 48 h. Seed hardening (24 h) and the traditional soaking treatments resulted in a higher germination percentage, germination index and energy of germination and lower mean germination time and mean emergence time. Performance was slightly better in seeds subjected to hardening for 24 h than the traditional soaking because of lower T₅₀ and non-reducing sugars and higher reducing and total sugars and α-amylase activity. In seeds subjected to osmoconditioning for 48 h seed performance was impaired possibly because of KNO₃ toxicity.