Osmotic priming of rice seeds subjected to low temperatures

Abstract

Aiming at verifying effects of priming on germination and emergence of seeds subjected to low temperatures, rice seeds (cv. IRGA 418) were primed into a KNO3 solution during 24, 48, and 72 h, at 20 °C; and into distilled water, for 24 h (control). Germination (G), first count of germination (FCG), and germination speed index (GSI) were the parameters assessed under temperatures of 17 °C, 20 °C and 25 °C. Besides, field emergence (FE), and emergence speed index (ESI) were also assessed under field conditions. A completely randomized design was used with treatments arranged in 4 x 3 factorial (treatments x temperatures) in all experiments. None statistically significant difference was found for seed germination within the 24 h imbibition period, under any of temperatures assessed; although after 48 and 72 h, at 17 °C, this variable has decreased. When seeds were imbibed in KNO3, during 48 and 72 h, the FCG and GSI were decreased, as compared to 24 h imbibition period, and for control treatment, at 17 °C and 25 ºC. After 24 h imbibition, the FE has not differed statistically from control treatment; as occurred for periods of 24 and 48 h imbibition for the ESI parameter. Priming in KNO3 does not cause beneficial effect on seed germination or on seedling emergence of rice.