减氮增密对杂交水稻创两优669产量与镉积累转运的影响

Effects of Reducing Nitrogen and Increasing Density on Yield and Cadmium Accumulation and Transportation of Chuangliangyou 669 in Hybrid Rice

为探究减氮增密对杂交稻产量与镉积累转运的影响,以创两优669为材料,设置3个氮肥水平(N1180 kg/hm^(2)、N2153 kg/hm^(2)、N3126 kg/hm^(2))与2个密度(M120.0 cm×16.7 cm、M216.7 cm×16.7 cm)处理,在湖南郴州镉污染稻田开展大田试验。结果表明:减氮使水稻干物质重、有效穗数、每穗总粒数和产量降低,但增密可提高有效穗数和产量,本试验条件下以N1M2处理的产量最高,N2M2处理次之;密度对水稻镉吸收转运的影响在年度和器官之间存在差异,减氮可降低土壤有效镉含量和根—叶镉转运系数,从而降低部分器官的镉含量;N1处理的糙米镉含量高于国家标准(0.20 mg/kg),而N2、N3处理的糙米镉含量低于国家标准,且显著低于N1处理。综上,减氮增密主要是通过减氮实现水稻降镉,减氮15%~30%可使糙米镉含量降到国家安全标准以下。综合产量与糙米镉含量,N2M2(减氮15%、增密)为最佳减氮增密处理,可在显著降低糙米镉含量的同时获得较高产量。

In order to investigate the effects of reducing nitrogen and increasing density on yield and cadmium accumulation and transportation of hybrid rice,using Chuangliangyou 669 as the materials,three nitrogen levels(N1180 kg/hm^(2),N2153 kg/hm^(2),N3126 kg/hm^(2))and two densities(M120.0 cm×16.7 cm,M216.7 cm×16.7 cm)were applied in a feld experiment with the paddy fields polluted by cadmium in Chenzhou,Hunan Province.The results showed that nitrogen reduction reduced the dry matter weight,the number of effective panicles,the number of spikelets per panicle and yield of rice.However,increasing density improved the number of effective panicles and yield.Under the experimental conditions,N1M2 treatment had the highest yield,followed by N2M2 treatment.The effects of density increase on cadmium uptake and transport in rice was different among years and organs,but nitrogen reduction reduced the available cadmium content in soil and the cadmium transport coefficient from root to leaf,thereby reducing the cadmium content in some organs.The cadmium content in brown rice under N1 treatment was higher than the national standard(0.20 mg/kg),while the cadmium content in brown rice of N2 and N3 treatments,significantly lower than that of N1 treatment,was lower than the national standard.In a word,the reduction of cadmium content in rice was mainly realized by reducing nitrogen application,and a 15% to 30% reduction in nitrogen can bring the cadmium content in brown rice below the national safety standard.Considering both yield and cadmium content of brown rice,N2M2(15% nitrogen reduction&densification)is the optimal treatment for achieving a significant reduction in cadmium content of brown rice while achieving a higher yield.