Abstract
Soil salinity is one of the important abiotic stress factors that affect rice productivity and quality. Research with several dicotyledonous plants indicated that the detrimental effects associated with salinity stress can (partly) be overcome by the external application of antioxidative substances. For instance, sodium selenate (Na2SeO4) significantly improved the growth and productivity of several crops under various abiotic stress conditions. At present there is no report describing the impact of Na2SeO4 on salinity stressed cereals such as rice. Rice cultivation is threatened by increasing salinity stress, and in future this problem will further be aggravated by global warming and sea level rise, impacting coastal areas. The current study reports on the effect of Na2SeO4 in alleviating salinity stress in rice plants. The optimal concentration of Na2SeO4 and the most efficient mode of selenium application were investigated. Selenium, sodium, and potassium contents in leaves were determined. Antioxidant enzyme activities as well as proline, hydrogen peroxide (H2O2), and malondialdehyde (MDA) concentrations were analyzed. In addition, the transcript levels for OsNHX1, an important Na+/H+ antiporter, were quantified. Treatment of 2-week-old rice plants under 150 mM NaCl stress with 6 mg l-1 Na2SeO4 improved the total biomass. A significantly higher biomass was observed for the plants that received Na2SeO4 by a combination of seed priming and foliar spray compared to the individual treatments. The Na2SeO4 application enhanced the activity of antioxidant enzymes (SOD, APX, CAT, and GSH-Px), increased the proline content, and reduced H2O2 and MDA concentrations in plants under NaCl stress. These biochemical changes were accompanied by increased transcript levels for OsNHX1 resulting in a higher K+/Na+ ratio in the rice plants under NaCl stress. The results suggest that Na2SeO4 treatment alleviates the adverse effect of salinity on rice plant growth through enhancing the antioxidant defense system and increase of OsNHX1 transcript levels.
Highlights
Global agricultural productivity is strongly influenced by several abiotic stress factors including cold, drought, soil salinity, flood, and high temperature
A significant reduction in the length (44.2 and 50.2%) and fresh weight (FW) (55.4 and 45.6%) of roots and shoots (Figures 1A–D), and total biomass (48.7%) (Figure 2A) was observed in rice plants exposed to the salt stress
A concentration of 6 mg l−1 Na2SeO4 was found to be optimal since the length and FW of roots and shoots (Figures 1A–D) and total biomass (Figure 2A) of the rice plants under NaCl stress was higher than for other concentrations tested
Summary
Global agricultural productivity is strongly influenced by several abiotic stress factors including cold, drought, soil salinity, flood, and high temperature. Among these abiotic stresses, soil salinity is one of the most devastating environmental stresses, which causes reduction in the cultivable land, crop productivity and quality (Shrivastava and Kumar, 2015). It has been estimated that 20% of total cultivated and 33% of irrigated agricultural lands worldwide are already affected by high salinity. Salinity affects plant growth and development by imposing osmotic stress on plants, and causes an imbalance in cellular ionic flux resulting from altered Na+/K+ ratios and Na+ and Cl− ion concentrations inside cells (Subramanyam et al, 2011). The ionic influx causes oxidative stress which in turn affects the activity of major cytosolic enzymes by disturbing intracellular potassium homeostasis, and negatively affects photosynthesis (Subramanyam et al, 2012)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
