The influence of dissolved oxygen around rice roots on salt tolerance during pre-tillering and tillering phases

Abstract

Rice is a strategic crop that has a high tolerance to hypoxia compared to other species. Our purpose was to investigate the salinity-acclimation mechanisms in rice plants triggered by hypoxia in the nutrient solution. So, the development of radial O2-loss barriers and physiological and biochemical responses against salinity were evaluated in rice plants (cv. SCSBRS 113) grown under saline stress and subjected to different levels of dissolved oxygen around of root in the pre-tillering and tillering phases. Our results reported an interaction between hypoxia and salinity treatments. Salinity acted as a much harsher pressure than severe hypoxia, particularly in the pre-tillering stage. However, severe hypoxia was able to aggravate the physiological stress imposed by salinity in the tillering stage, and combination with salinity contributed to a reduction of Ca2+ and K+ content. Besides, the radial O2-loss barrier did not reduce the influx or efflux of water and ions. It also was unrelated to a root shortening and decreased relative water content in leaves. The hypoxia attenuation did not contribute much to the better growth and development of rice plants, and the radial O2-loss barriers did not confer salinity tolerance by hindering Na+ and Cl− uptake.