Response to salinity in Glycine. VI. Some effects of a range of short-term salt stresses on the growth, nodulation, and nitrogen fixation of Glycine wightii (Formerly Javancia)

Abstract

Well-nodulated plants of Glycine wightii (formerly G. javanica) grown in sand culture were subjected to 14 days of salinity ranging from nil to 148 m-equiv. sodium chloride per litre of nutrient solution, and the response compared with that of similarly treated nitrogen-fertilized plants. The latter showed less tissue injury and a smaller reduction in growth rate at high salinity than the inoculated plants. During salinity treatment the development of new nodules, and nitrogen fixation by the existing nodules, were greatly inhibited, with a resulting marked decline in plant nitrogen concentration, especially in the laminae and nodules. Despite the severity of the salt effect on the inoculated plants, the nodules developed prior to salt treatment appeared remarkably resistant to stress, and rapidly regained pigmentation and efficiency of nitrogen fixation when the sodium chloride was removed from the culture solutions. Salt accumulation in the nodules was limited and the sensitivity of the symbiosis to salinity appeared primarily dependent on the host. These factors indicate the adaptability of the symbiosis to increases in substrate salinity.