Effects of Enhanced Ammonium Nutrition on the Growth and Quality of Spinach

Four cultivars of spinach were grown in nutrient solution with four different ratios of NH~+_4-N to NO~-_3-N,(100/0,25/75,50/50,and 0/100).The results obtained were as follows.Different ratios of NH~+_4-N to NO~-_3-N had great effects on the growths of spinach.The biggest biomass of spinach was found in the ratios of NH~+_4-N to NO~-_3-N of 0/100 showing that spinach preferred nitrate to ammonium nutrition.The content of nitrate were decreased but soluble sugar content was increased with the increasing proportion of NH~+_4-N indicating that addition of some ammonium could improve the quality of spinach.