关键词: 水稻, 施氮量, 种植密度, 产量, 糙米Cd含量, 珞优2号

Abstract:

Taking the single season late rice varity Luoyou 2 with low cadmium absorption as the research material, under the conditions of total Cd content of 3.39 mg/kg and effective Cd content of 0.59 mg/kg in the experimental field, we set up five nitrogen fertilizer application treatments (applying pure nitrogen 0, 90, 120, 150, 180 kg/hm², denoted as N0, N1, N2, N3, N4) and three planting density treatments (240 000, 300 000, 360 000 clusters/hm², denoted as D1, D2, D3). This study aims to explore the effects of different nitrogen application rates and planting densities on rice yield, aboveground biomass accumulation, population growth rate, nitrogen fertilizer use efficiency, and Cd content in brown rice. The results showed that nitrogen application rate, planting density, and their interaction had a significant impact on rice yield. Among them, the N3D3 treatment had the highest yield, reaching 9.7 t/hm². The main reason for its high yield attributed to a higher number of effective panicles. The Cd content in brown rice of N3D1, N3D2, and N3D3 treatments was between 0.17-0.20 mg/kg, all below the safety limit standard for cadmium content in rice. Under the conditions of this experiment, the Cd content in brown rice of all nitrogen fertilizer treatments was stably below 0.20 mg/kg. With the increase of planting density, both rice yield and Cd content in brown rice showed an upward trend. When the planting density was below 378 000 clumps/hm², the Cd content in brown rice could be stably maintained below 0.20 mg/kg. In summary, when the nitrogen application rate is 150 kg/hm² and the planting density not exceeding 378 000 clusters/hm², Luoyou 2 can exert its high-yield characteristics and cadmium-low absorption characteristics, which is beneficial for achieving safe production.

Key words: rice, nitrogen application rate, planting density, yield, Cd content in brown rice, Luoyou 2