Effect Of Potassium On Soybean Under Short-Term Salinity

ABSTRACT: A saline-tolerant soybean advanced line AGS313 from Bangladesh and a saline-sensitive variety Fukuyutaka from Japan were cultivated in pots under short-term saline condition to evaluate the effects of potassium (K+ ) application on mitigation of salt stress effect. Three levels of K+ (2, 4, and 8mM) were prepared in a half-strength ‘Enshi’ solution to apply on the pots from 13 days after seed sowing. The plants at the vegetative stage were subjected to 50 mM NaCl treatment for 15 days. The physiological responses such as photosynthetic rate, transpiration rate, relative water content, leaf water potential (LWP), and exudation rate were measured. The accumulation of Na+ and K+ in the leaves were also measured. The yield components were recorded at harvest. The results indicated that all the physiological parameters, except LWP were decreased by NaCl application, regardless of K+ concentrations. Both the soybean varieties controlled Na+ transport into their leaves. AGS313 accumulated the highest amount of K+ in the leaves with 8 mM K+ application regardless of NaCl treatment. Salinity affected number of pods in AGS313 only, while seeds per pod in Fukuyutaka. However, 100-grain weight was not affected by the salinity. Thus, the yield reduction for AGS313 and Fukuyutaka were attributed to number of pods and number of seeds per pod, respectively. Salinity damage on AGS313 yield was alleviated considerably by K+ application. However, the yield improvement by K+ was not significant. This inconclusive improvement was probably caused by the restricted Na+ transportation under short-term salinity. 

Keywords: Glycine max, salinity, ion accumulation, yield component