Effect of short term cold stress on rice seedlings

A method was developed for exposing rice seedlings to low temperatures for short periods. These seedlings were from 70 F9 inbred lines derived originally from a hybrid of a salt tolerant cultivar, which provided a source of resistance to abiotic stress, and a non salt tolerant cultivar as the other parent. Seedlings were grown hydroponically in a warm growth room then placed in the air above a freezing bath for 6 hours at –0.2 °C, –1.0 °C or –2.0 °C before returning them to the growth room for a 7–10 day period. Seedling survival in the inbred lines of rice was compared after exposure to these temperature treatments to identify the presence of low temperature tolerance. An average survival of 93%occurred 7days after exposures to –0.2, and –1.0 °C and a survival of 35% after an exposure of –2.0 °C. The non-salt tolerant parent cultivar was killed by exposure to –2.0 °C but the salt tolerant parent survived. The effect of low temperature exposure was examined in more detail in lines selected for low temperature tolerance and susceptibility. Alterations to the total leaf protein profile, including fragmentation of Rubisco, were observed in these lines but no obvious difference was detected between susceptible and tolerant individuals.