Carbon and nitrogen metabolisms in rice growing with different levels of nitrogen fertilization under alkaline soil

A salt-affected alkali stress disrupts ion balance via water stress in plants, resulting in a malfunction of nutrient availability and physiological metabolism, and this trend is dominant in alkali soils possessing lower nutrient levels.This study aimed to investigate how an adjustment of nitrogen fertilization rates affects rice growth and carbon and nitrogen metabolisms.To achieve this goal, three levels of nitrogen fertilization, 0, 75 and 15 kg ha -1 , were incorporated into high pH soil (pH 9.2), and subsequent cultivation was followed by RDA manual.Leaves and roots from rice plants (cv.Asemi, alkali-tolerant) were harvested at tillering and heading stages.An increase in N fertilization did not promote growth, biomass production and N uptake.Alkali condition resulted in an accumulation of soluble sugar and starch in 0 kgN-fed roots, whereas 150 kgN showed reduced starch in leaves and roots.N deficit (0 kgN) up-regulated OsNADH-GOGAT in the roots, meanwhile high N (150 kgN) stimulated up-regulation of OsGS1;2.This study concluded that an adjustment of N fertilization rates was not effective in terms of growth and primary metabolism in low nutrients-containing alkali soils.Accordingly, we propose that subsequent study is required to examine the effect of N fertilization with diverse nutrients-containing alkali soils.