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The effects of raw attapulgite clay and thermally modified attapulgite clay on the growth status of submerged plant Vallisneria Spiralis (V. spiralis) and the microenvironment of sediment were first explored. The results demonstrated that the attapulgite could effectively promote the development of V. spiralis and improve plant stress resistance by enhancing the activity of antioxidant enzymes. The 10% addition of attapulgite clay increased the biomass of V. spiralis by 27%∼174%, and the promoted rate of raw attapulgite clay was 2∼5 times of modified attapulgite clay. The attapulgite increased redox potential in sediment (P < 0.05) and provided proper niches for organism propagation, further promoting the degradation of organic matter and nutrient metabolism in sediment. The value of Shannon, Chao, and Ace was 9.98, 4865.15, 5029.08 in the 10% modified attapulgite group, and 10.12, 4856.85, 4947.78 in the 20% raw attapulgite group, respectively, indicating that the attapulgite could increase the microbial diversity and abundance in sediment. Additionally, the nutrient elements, such as Ca, Na, S, Mg, K, Zn, and Mo, that dissolved from attapulgite may also promote the V. spiralis growth. This study provided an environment-friendly approach to facilitating submerged macrophyte restoration in the eutrophic lake ecosystem. [Display omitted] • Effects of attapulgite on V. spiralis growth and sediment microenvironment. • Attapulgite can improve the sediment microenvironment. • Attapulgite can effectively promote the growth of V. spiralis. • Sediment microenvironment was important to plant growth. • Elements dissolved from attapulgite may also promote the plant growth. [ABSTRACT FROM AUTHOR]

The effects of clay mineral bentonite on the growth process of submerged macrophyte V. spiralis and sediment microenvironment were investigated in the study for the first time, aiming to determine whether it is suitable for application in the field of ecological restoration. The growth index, and physiological and biochemical index of V. spiralis in the experiments were measured once a month, and the changes of rhizosphere microorganisms and physicochemical properties of sediments were also studied at the same time. The results demonstrated that bentonite can effectively promote the growth of V. spiralis. The treatment groups of RB1/1 and MB1/5 (the mass ratios of bentonite to sediment were 1/1 and 1/5, respectively.) showed the best V. spiralis growth promotion rates which were 18.78%, and 11.79%, respectively. The highest microbial diversity and abundance existed in group of RB10 (the mass ratio of sediment to bentonite was 10/1), in which the OTUs, Shannon, Chao and Ace were 1521.0, 5.20, 1712.26, and 1686.31, respectively. Bentonite was conducive to the propagation of rhizosphere microorganisms, and further changed the physical and chemical properties of the sediment microenvironment. The nutrient elements dissolved from bentonite may be one of the main reasons that promoted the growth of V. spirali s. The purpose of this result is to prove that bentonite can be further applied as sediment improver and growing media in ecological restoration projects in eutrophic shallow lakes. [Display omitted] • Effects of bentonite on growth process of V. spiralis and sediment microenvironment. • Bentonite can effectively promote the growth of V. spiralis. • Bentonite was conducive to the propagation of rhizosphere microorganisms. • Bentonite changed physical and chemical properties of the sediment microenvironment. • Nutrient dissolved from bentonite may be a reason promoted growth of V. spiralis. Bentonite can effectively promote the growth of V. spiralis. Bentonite was conducive to the propagation of rhizosphere microorganisms, and further changed the physical and chemical properties of the sediment microenvironment. [ABSTRACT FROM AUTHOR]