Comparison of nitrate accumulation, nitrogen uptake and utilization efficiency among different spinach (Spinacia oleracea L.) genotypes

A hydroponic experiment was conducted to study the difference of nitrate accumulation,nitrogen uptake and utilization efficiency between four spinach (Spinacia oleracea L.) genotypes (So10,So13,So18 and So57). Results showed that So13 had the highest nitrate contents under two nitrate (NO3--N) level (0.5 mmol·L-1,15 mmol·L-1) conditions,whereas So10 had the lowest nitrate contents. So18 had the similar nitrate contents with So13 under low NO3- level,while it showed no significant difference of nitrate contents with So57 under high NO3- treatment. The 15NO3--N uptake rates of So13 were the highest one among four genotypes,while the N utilization efficiency (NutE) and N utilization ratio (NUR) of So13 were significantly lower than those of So18 and So57. The shoot dry mass,nitrate reductase activity,NutE,NUR of So18 and So57 were higher than those of So13 and So10,while their 15NO3--N uptake rates were lower than those of So13. The shoot dry mass,nitrate reductase activity,NutE,N utilization ratio of So10 were significantly lower than those of So18 and So57,and its 15NO3--N uptake rate was significantly lower than those of So13. Among the four spinach genotypes,the So57 can be selected as elite germplasm using for spinach production for its relatively lower nitrate content and higher N efficiency.