Abstract:A rapid diagnosis of nitrogen nutrition status in the soil is fundamental for precise fertilization during the remediation and safe use of heavy metal polluted paddy soils. Determination of leaf chlorophyll content using the SPAD (soil and plant analyzer development) Chlorophyll Meter has been widely used as nitrogen nutrition diagnosis for corn, wheat and cotton. However, its applicability in rice plant is unclear for the different types of paddy soils under cadmium (Cd) pollution. In this study, twenty-one types of paddy soils collected in the main rice-planting regions of China were used for a pot experiment with a rice variety (DN 2000). Three Cd pollution treatments were established: without Cd addition (no Cd pollution), low dose Cd addition (slight Cd pollution), and high dose Cd addition (severe Cd pollution). Rice leaf SPAD values and nitrogen concentrations in soil solutions were measured at seedling, tillering, jointing, heading and mature stages. The results showed that soil type had a significant impact on the response of rice leaf SPAD value to Cd pollution, and soil pH played an important role (with an average relative contribution of 20%) on the variation of SPAD value. SPAD values were significantly correlated to rice grain nitrogen concentrations, with the highest correlation coefficient in the jointing stage. At the same time, SPAD values were significantly correlated with the total nitrogen and ammonium nitrogen concentrations in soil solutions at seedling and tillering stages, which was independent of Cd pollution level and soil type. In general, rice leaf SPAD value during rice growth season, especially at the jointing stage, could characterize the impact of soil nitrogen supply on nitrogen nutrition status of rice plant in different paddy soils under Cd pollution.