Abstract:
To explore the application effect of different "VIP+n" technology (V, planting of low-cadmium accumulation varieties; I, optimized irrigation management; P, applying lime; n, spraying foliar inhibitor) on Cd content of double-cropping rice from acidic paddy field with different degrees of heavy metal pollution, the "VIP+n" technology were carried out in the lightly, mediumly and heavily cadmium-polluted rice fields in Xiangtan City of Hunan in 2017. The "VIP+n" technology had significant or extreme significant effects on the content of Cd in brown rice of double-cropping paddy field and soil pH (
P < 0.05 or 0.01). The pollution degree of Cd in paddy field had significant or extremely significant effects on the content of Cd in brown rice of double-cropping paddy field and the contents of total Cd and extractable Cd in soil (
P < 0.05 or 0.01). And their interaction effects on the content of Cd in brown rice of late-rice were significant (
P < 0.05). The Cd contents of brown rice for early-rice were 0.29, 0.88 and 3.85 mg·kg
-1, respectively, under lightly, moderately and heavily Cd polluted soil, and those for late rice were 0.22, 0.55 and 2.64 mg·kg
-1, respectively. However, the Cd contents of early-rice with "VIP+n" technology were 0.09, 0.34 and 1.17 mg·kg
-1 with a reduction of 70.00%, 61.19% and 69.66%, respectively, significantly different from the control (
P < 0.05), and those for late-rice were 0.03, 0.32 and 1.01 mg·kg
-1 with a reduction of 87.16%, 41.49% and 61.71%, respectively, significantly or extremely significantly different from the control (
P < 0.05 or 0.01). Hence, the application effect of "VIP" technology was better for late-rice than that for early-rice. The correlation analysis show that the Cd contents of brown rice at the mature stage of double-cropping rice were negatively correlated with soil pH (
rearly=-0.002;
rlate=-0.181), but positively correlated with the extractable Cd content of soil (
rearly=0.658,
P < 0.01;
rlate= 0.772,
P < 0.01). The "VIP+n" technology can effectively improve the soil pH, reduce the Cd content of brown rice from double-cropping paddy fields with different degrees of Cd pollution, and under light Cd pollution make it meet the National Food Safety Standards (GB 2762-2017).