Zhou Qingyun, Wang Hui, Xu Chao, Zheng Shen, Wu Meiyan, Zhang Quan, Liao Yulin, Zhu Hanhua, Zhu Qihong, Huang Daoyou
Key Laboratory for Agro-Ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha, 410125, China.
College of Agriculture, Yangtze University, Jingzhou, 434025, China.
Environ Sci Pollut Res Int. 2022 Jul;29(33):50530-50539. doi: 10.1007/s11356-022-19381-x. Epub 2022 Mar 1.
Cadmium (Cd) pollution in paddy soils creates challenges in rice grain production, thereby threatening food security. The effectiveness of different base-tillering-panicle urea application ratios and the combined basal application of urea and Chinese milk vetch (CMV, Astragalus sinicus L.) in minimizing Cd accumulation in rice grains was explored in a Cd-contaminated acidic soil via a field experiment. The results indicated that under similar nitrogen (N) application rates, an appropriate amount of urea applied at the panicle stage or the combined basal application of urea and CMV decreased Cd absorption by rice roots and its accumulation in rice grains, as compared with that of conventional N application (control). Furthermore, under a 3:4:3 base-tillering-panicle urea application ratio or under a high basal application of CMV (37,500 kg hm), Cd concentrations in brown rice were significantly lower (40.7% and 34.1%, respectively) than that of control. Cadmium transport coefficient from root to straw was significantly higher than that of control when an appropriate amount of urea was applied at the panicle stage or when urea and CMV were applied basally, whereas the Cd transport coefficient from straw to brown rice was relatively lower. Moreover, soil pH, or the CEC and CaCl-Cd concentrations under different N fertilizer treatment was not significantly different. However, the rice grain yield increased by 29.4% with basal application of a high CMV amount compared with that of control. An appropriate amount of urea applied at the panicle stage or the combined basal application of urea and CMV decreased Cd absorption by rice roots and inhibited its transport from straw to brown rice, thus reducing Cd concentration in brown rice. Therefore, combined with the key phase of Cd accumulation in rice, a reasonable urea application ratio or a basal application of high CMV amounts could effectively reduce Cd concentration in brown rice.
稻田土壤中的镉（Cd）污染给水稻籽粒生产带来了挑战，进而威胁到粮食安全。通过田间试验，在受镉污染的酸性土壤中，探究了不同基肥-分蘖-穗肥尿素施用比例以及尿素与紫云英（CMV，Astragalus sinicus L.）基肥配合施用对降低水稻籽粒中镉积累的效果。结果表明，在施氮量相似的情况下，与传统施氮（对照）相比，在穗期施用适量尿素或尿素与紫云英基肥配合施用，可降低水稻根系对镉的吸收及其在水稻籽粒中的积累。此外，在基肥-分蘖-穗肥尿素施用比例为3:4:3或紫云英高基肥用量（37500 kg·hm）的情况下，糙米中的镉浓度显著低于对照（分别低40.7%和34.1%）。当在穗期施用适量尿素或基肥中施用尿素和紫云英时，镉从根系向稻草的转运系数显著高于对照，而从稻草向糙米的镉转运系数相对较低。此外，不同氮肥处理下的土壤pH值、阳离子交换量（CEC）和氯化钙提取态镉浓度无显著差异。然而，与对照相比，紫云英高基肥用量处理的水稻籽粒产量提高了29.4%。在穗期施用适量尿素或尿素与紫云英基肥配合施用，可降低水稻根系对镉的吸收，并抑制其从稻草向糙米的转运，从而降低糙米中的镉浓度。因此，结合水稻镉积累的关键时期，合理的尿素施用比例或紫云英高基肥用量可有效降低糙米中的镉浓度。
