To compare the effects of different soil tillage methods (ploughing

rotary tillage and no tillage) on rice yield composition and cadmium accumulation and distribution traits in rice panicles in southern double-cropping rice fields

and to explore the optimal soil tillage method for double-cropping rice in cadmium-contaminated rice fields

taking "Lingliangyou 211"and "Weiyou 46"as early and late rice varieties

the available cadmium content in soil

rice yield components and spike cadmium accumulation and distribution of double-cropping rice under five soil tillage methods (double-cropping no-tillage

double-cropping ploughing

double-cropping rotary tillage

ploughing in early rice and no-tillage in late rice

rotary tillage in early rice and no-tillage in late rice) were studied in Yisuhe Town

Xiangtan County

Hunan Province in 2015 to 2017. The experimental field was cadmium-contaminated rice fields

and the total cadmium content was 0.86 mg/kg. The results showed that the yield of double cropping rice was the highest in the treatment of double-cropping ploughing

followed by the treatments of ploughing in early rice and no-tillage in late rice

double-cropping rotary tillage and rotary tillage in early rice and no-tillage in late rice

and that of no-tillage in double cropping rice was the lowest. The highest yield of ploughing treatment was due to the higher number of effective panicle and grains per panicle. (2) The cadmium content in panicle generally showed an increasing trend from full heading to maturity stage. In the first year of early and late rice

the cadmium content in panicle at full heading stage was the highest in no-tillage treatment

but no-tillage could significantly reduce the growth rate of cadmium content in panicle from full heading to maturity stage. The cadmium content in panicle at maturity stage was higher in ploughing treatment and lower in no-tillage and rotary tillage treatment

there were difference between no-tillage and rotary tillage treatment

but they were different among years and seasons. (3) Cadmium content in different parts of rice panicle at maturity stage followed the order of branches > husks > brown rice. The cadmium content in brown rice was higher in no-tillage treatment in the first year

but in the second and third years

that of no-tillage was lower than that of ploughing and rotary tillage. (4) The cadmium accumulation in panicle of early and late rice was lower in rotary tillage treatment in the first year

but it was lower in no-tillage treatment in the second and third years. (5) Compared with other treatments

double-cropping no-tillage significantly improved the soil available cadmium content

while double-cropping rotary tillage decreased the soil available cadmium content. The three-year locational test showed that soil tillage methods had a significant impact on available cadmium in soil

yield components and cadmium accumulation and distribution in rice panicles of double-cropping rice in cadmium-contaminated paddy field. From the perspective of ensuring the yield of double-cropping rice

reducing cadmium content in rice and saving labor

ploughing in early rice and no-tillage in late rice was the optimal soil tillage method for medium cadmium-contaminated double-cropping rice fields.