Abstract

Salinity is one of the main obstacles in increasing rice production worldwide. Even though rice is considered to be a salt-sensitive or moderately sensitive crop, the development of salt tolerant cultivars is essential to coping with the simultaneous increases in global population and salinization in arid and semi-arid areas. Over the course of the project, 5 rice cultivars from two subspecies (Indica and Japonica) were exposed to salt doses (0, 50 and 100 mM, NaCl) in several independent experiments. The experiments were carried out in high light growth chambers beginning with young plantlets at the three-leaf stage grown hydroponically. The plants were characterized based on morpho-physiological traits and ions profile under salinity treatments. Morpho-physiological evaluation of cultivars after exposure to salinity showed marked variability in response to salinity. The growth retardation response of japonica cultivars to salinity was much greater than that of indica cultivars. Reduction in the root:shoot ratio of plants under salt stress was a common behavior among the cultivars. The chlorophyll fluorescent quantum yield and electrolyte leakage of cultivars decreased and increased respectively after exposure to salinity. The nutrient profile of cultivars under salt stress revealed that the tolerant cultivars exhibit significantly higher K/Na ratios in their leaves than sensitive cultivars. Boron, copper and sulphur didn’t change significantly. The contents of cadmium, cobalt, chromium, nickel and selenium in rice cultivars were below the detection limits. Moreover, salinity in high doses makes molybdenum deficiency the same as iron deficiency in rice plants.

Keywords: Chlorophyll fluorescent; Electrolyte leakage; Indica ; Ion homeostasis; Japonica ; K/Na ratios; Root; Shoot