THE NITRATE CONTENT DIFFERENCE AND THE REASON AMONG FOUR SPINACH VARIETIES

The nitrate content difference among four spinach varieties under three nitrogen levels was studied in a pot experiment. The results showed that, there wasn't remarkable difference of shoot and root biomass among four varieties, and a large difference of nitrate content among four varieties with N supply. The nitrate content of Daye and Jianye was 2500～3000 mg/kg FW, always higher than that of Bozha 15 and Lufeng (near 2000 mg/kg, FW). Bozha 15 and Lufeng had a higher NRase activity than Daye and Jianye when N was supplied. It was the main reason of nitrate content difference among four varieties. There was a significant negative line correlation between nitrate content and NRase activity with N treatments. It shows that selecting and breeding some good varieties to reduce nitrate content is practicable.