关键词: 冬小麦, 土壤镉污染, 土壤镉钝化剂, 复合微生物肥, 镉富集系数, 镉转运系数, 石灰性潮土

Abstract:

【Objective】The passivation effect of passivator and compound microbial fertilizer on cadmium (Cd) activity in slightly Cd-polluted weak alkaline farmland soil in northern Henan Province was studied, and their effects on Cd accumulation and translocation in different organs and yield of winter wheat were investigated too. The purpose of this study was to explore soil remediation materials for efficient remediation of Cd-contaminated soil, to reduce Cd content in winter wheat grains, and to screen wheat varieties with low Cd accumulation, so as to provide the technical support for the safe and efficient production of wheat in lightly polluted weak alkaline farmland in northern Henan Province. 【Method】In two consecutive winter wheat growing seasons of 2020-2022, two-factor split field comparison experiments of four different soil remediation materials (CK, no soil remediation treatment; CMF, single application of compound microbial fertilizer; GP, single application of soil passivator; CMF+GP, combination of compound microbial fertilizer and soil passivator) and six winter wheat varieties (Xinhuamai818, Luomai 163, Zhengmai 9023, Xinmai 296, Zhengmai 136, and Zhengmai 7698) in northern Henan Province were set up and used in the weakly Cd-polluted alkaline farmland. The changes of available Cd in soil, Cd contents in aboveground organs of wheat plants, enrichment coefficient (BCF), transport coefficient (TF), their correlations, and winter wheat yields and its components were analyzed. 【Result】(1) In two winter wheat growing seasons (2020-2021 and 2021-2022), compared with CK, single application and equal combination application of passivation agent and compound microbial fertilizer could remarkably reduce the content of available Cd in soil. CMF+GP treatment had the best effect, which significantly and effectively reduced the available Cd content by 17.6%-22.4% in the surface soil of the roots among the six varieties. The decreased available Cd in soil was related to the changes of Cd content in the aboveground organs of winter wheat plants, and there were also some differences between the same organs of different varieties. (2) Single application of soil passivator and compound microbial fertilizer, as well as equal combined application of soil passivator and compound microbial fertilizer, could make Xinhuamai 818, Luomai 163 and Zhengmai 9023 decrease TF_{Stem sheath-leaf}, TF_{Stem sheath-grain}, increase TF_{Stem sheath-(Spike shaft+chaff)}, TF_{Leaf-(Spike shaft+chaff)}, reduce BCF_{Stem sheath} and BCF_Leaf, and make wheat body in order to reduce BCF _Grain, the content of Cd in it shifted to panicle axis + glume. In contrast, they did not reduce TF_{Stem sheath-Leaf} and BCF _{Stem sheath} of Xinmai 296, whereas increased BCF _{Stem sheath} of Zhengmai 136 and Zhengmai 7698. (3) Application of passivating agents and compound microbial fertilizers in soil could comprehensively regulate the number of ears, grains per ear and 1000-kernel weight of winter wheat plants, and improve the grain yields of winter wheat. However, variance analysis on soil remediation treatment and varieties showed that the increased grain yields in their interactions was mainly due to the increased ear numbers. Under CMF+GP treatment, the grain yield of Zhengmai 136 variety was the highest among all treatments, which was 7 317.17 kg·hm^-2 and 10 485.32 kg·hm^-2 in two consecutive 2020-2021 and 2021-2022 winter wheat growing seasons, respectively. 【Conclusion】The application of compound microbial fertilizer and soil passivator could effectively reduce the available Cd content in the rhizosphere soil with weak alkaline and mild Cd pollution in northern Henan Province, and regulate the enrichment coefficient and transport coefficient of soil Cd in various organs of winter wheat plants. The combination treatment of compound microbial fertilizer and soil passivator with the same applied amounts was better than single treatment, which could also reduce the Cd content of winter wheat grains to the maximum extent, and significantly improve the yield of winter wheat varieties. In addition, the combination of planting modes combined with the low Cd accumulation and high yield variety Zhengmai 136 screened out, could achieve the high grain yields and safe production of winter wheat in the farmland with weak alkaline Cd pollution in northern Henan Province.

Key words: winter wheat, soil Cd contamination, soil cadmium passivator, compound microbial fertilizer, Cd enrichment coefficient, Cd transport coefficient, calcareous fluvo-aquic soil