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Gamma-aminobutyric acid (GABA) is a signalling substance that related to the stress condition. To improve the cadmium (Cd) phytoremediation capacity of hyperaccumulator Galinsoga parviflora Cav., the effects of exogenous GABA on the Cd accumulation of G. parviflora were studied. The treatment of Cd (0.1 mg/L) decreased the biomass and photosynthetic pigment content of G. parviflora, indicating that Cd treatment produced stress to G. parviflora. Under Cd stress, exogenous GABA increased the biomass and photosynthetic pigment content of G. parviflora to some extent, and the applications of GABA at 1 and 2 g/L increased the shoot biomass by 10.36% and 28.83%, respectively, compared with Cd treatment. Exogenous GABA also increased the Cd content, bioconcentration factor, and Cd extraction of G. parviflora. The applications of GABA at 1 and 2 g/L increased the shoot Cd content by 13.39% and 16.53%, respectively, and increased the shoot Cd extraction by 25.25% and 49.83%, respectively, compared with Cd treatment. Therefore, GABA can alleviate Cd stress to G. parviflora and improve its phytoremediation capacity. [ABSTRACT FROM AUTHOR]

γ‐aminobutyric acid (GABA) has shown promise in enhancing crop tolerance to heavy metal stress. To improve the cadmium (Cd) phytoremediation capacity of hyperaccumulator Solanum nigrum var. humile, the effects of exogenous GABA on the growth and Cd accumulation of S. nigrum var. humile were studied. When exposed to Cd stress (0.1 mg/L) through irrigation, S. nigrum var. humile exhibited inhibited growth, characterized by decreased biomass and contents of photosynthetic pigments (chlorophyll a, chlorophyll b, total chlorophyll, and carotenoid). However, the application of exogenous GABA at 1 and 2 g/L increased various organs biomass and photosynthetic pigment content of S. nigrum var. humile to certain degree under Cd stress. Compared with the Cd treatment, the concentrations of 1 and 2 g/L GABA increased the shoot biomass by 8.24% and 16.62%, respectively. GABA also increased the Cd contents, bioconcentration factors, and Cd extractions in various organs of S. nigrum var. humile. Compared with the Cd treatment, the concentrations of 1 and 2 g/L GABA increased the shoot Cd extraction by 17.66% and 24.47%, respectively. Moreover, correlation and gray relational analyses showed that the shoot biomass, chlorophyll b content, and total chlorophyll content were the top three parameters closely related to shoot Cd extraction. These findings suggest that GABA can alleviate Cd‐induced stress in S. nigrum var. humile, thus enhancing its phytoremediation capacity for Cd‐contaminated soils. [ABSTRACT FROM AUTHOR]

To decrease the cadmium (Cd) uptake in rice and study the relationships of phosphorus (P), iron (Fe), and Cd uptakes in rice, the effects of four different tea types (green, black, dark, and white teas) on the P, Fe, and Cd accumulation in rice seedlings were studied. The results showed that only the black and dark teas increased the biomass of rice seedlings. The application of green, black, dark, and white teas increased the photosynthetic pigment content to some extent. Only the black tea increased the shoot P content, and the black, dark, and white teas increased the shoot Fe content. Compared with the control, only the black and dark teas decreased the shoot Cd content by 9.51% and 25.02%. Correlation and gray relational analyses showed that the root Cd content, soil pH value and soil exchangeable Cd concentration were the most closely associated with the shoot Cd content. The principal component and cluster analyses also showed the top three close cluster categories with shoot Cd content were root Cd content, soil exchangeable Cd concentration, and soil pH value. These findings indicate that the application of black and dark teas can promote the growth and decrease the Cd uptake of rice. [ABSTRACT FROM AUTHOR]

Strigolactone can improve the tolerance of plants to abiotic stress. To improve the phytoremediation capacity of cadmium (Cd) hyperaccumulator Galinsoga parviflora Cav., the effects of strigolactone (using strigolactone analog GR24 with the concentration of 1 and 2 μmol/L) on the Cd accumulation of G. parviflora were studied. Cd treatment at 0.1 mg/L inhibited the growth of G. parviflora. Under Cd stress (0.1 mg/L), GR24 had no significant effect on the biomass and catalase activity of G. parviflora, while it decreased the peroxidase activity and increased the superoxide dismutase activity. In addition, GR24 decreased the root Cd content and root Cd extraction. GR24 at 1 μmol/L increased the shoot Cd content, shoot Cd extraction, bioconcentration factor, and translocation factor, while at 2 μmol/L, the opposite effect was observed. When the concentration of GR24 was 1 μmol/L, the shoot Cd content and shoot Cd extraction increased by 8.75% and 12.35%, respectively, compared with control. Moreover, correlation and grey relational analyses showed that the translocation factor, shoot Cd content, and plant height were the top three most highly correlated parameters with the shoot Cd extraction. These findings suggest that GR24 at 1 μmol/L can improve the phytoremediation capacity of G. parviflora for Cd. [ABSTRACT FROM AUTHOR]

The aim of this study was to determine the effects of spraying an algal biostimulant at different concentrations (0, 600-, 900-, 1200-, and 1500-fold dilutions) on the growth and cadmium (Cd) accumulation characteristics of accumulator plant Nasturtium officinale. In a pot experiment, application of the algal biostimulant at all concentrations promoted the growth of N. officinale by increasing the root and shoot biomasses, and the 600-fold dilution of the algal biostimulant had the strongest effect. At all concentrations, the algal biostimulant had no significant effect on the Cd content in roots of N. officinale, and increased the Cd extraction by roots. However, all concentrations of the algal biostimulant except for the 1500-fold dilution decreased the Cd content in shoots and Cd extraction by shoots. The N. officinale plants treated with the 600-fold dilution of the algal biostimulant had the lowest shoot Cd contents and Cd extraction by shoots. The algal biostimulant also increased the contents of photosynthetic pigments (chlorophyll a, total chlorophyll, and carotenoids) in leaves of N. officinale to varying degrees. Different concentrations of algal biostimulant reduced the superoxide dismutase activity, peroxidase activity, and malondialdehyde content of N. officinale, but enhanced the catalase activity, soluble protein content, and relative conductivity. Overall, the 600-fold dilution had the strongest effect on the growth and Cd accumulation characteristics of N. officinale, but did not enhance the phytoremediation ability of N. officinale for growth in Cd-contaminated soil. These results show that this algal biostimulant can promote the growth and reduce the Cd uptake of N. officinale, which is benefit for N. officinale safety production as a wild vegetable in Cd-contaminated soils. [ABSTRACT FROM AUTHOR]

A pot experiment was designed to explore the effects of different post-grafting generations of Solanum photeinocarpum Nakamura et Odashima intercropping on growth and cadmium (Cd) accumulation in soybeans (varieties: "Zaodou" and "Liaoxian"). Post generation of S. photeinocarpum (ungrafted, grafted on eggplant, potato, and tomato, respectively) were utilized to intercrop with two varieties of soybean in Cd-contaminated soil. Soybean monoculture was employed as a control. Consequently, intercropping with different post-grafting S. photeinocarpum generation, except for tomato rootstock grafts post-generation, could reduce soybean biomass and photosynthetic pigment content. Additionally, all S. photeinocarpum post-grafting generations had the capacity to reduce Cd content in soybean when intercropping, while tomato rootstock grafts post-generation exhibited an adequate ability to accumulate Cd in S. photeinocarpum compared to the ungrafted treatment. In particular, tomato rootstock grafts post-generation could effectively decrease Cd content in soybean organs by 14.09–62.13%, relative to soybean monoculture, but increased shoot Cd content and shoot Cd extraction of S. photeinocarpum by 10.33–13.49% and 10.38–12.03%, respectively, compared to the ungrafted treatment. Thus, tomato rootstock grafting may enhance the ability of post-grafting generation of S. photeinocarpum to remediate Cd-contaminated soil, and this grafting was able to reduce Cd accumulation in soybean. [ABSTRACT FROM AUTHOR]

In this experiment, four cadmium (Cd) hyperaccumulator species (Crassocephalum crepidioides, Galinsoga parviflora, Sigesbeckia orientalis, and Solanum nigrum) were intercropped with grape (Vitis vinifera) cuttings together in Cd-containated soil to study the effects of intercropping with the Cd-hyperaccumulator plants on growth and Cd accumulation of grape seedlings. Compared with the monoculture, intercropping with S. nigrum increased the biomass of grape seedlings, but intercropping with the other three hyperaccumulator species decreased the grape seedling biomass. Intercropping with S. nigrum increased chlorophyll a and total chlorophyll contents in leaves of grape seedlings compared with the monoculture, whereas intercropping with the other three hyperaccumulator species showed either a decrease or no effect. Intercropping with hyperaccumulator plants had no significant effects on chlorophyll b and carotenoid contents in leaves of grape seedlings compared with the monoculture. Compared with the monoculture, intercropping with C. crepidioides, G. parviflora, S. nigrum and S. orientalis significantly decreased Cd contents in shoots of grape seedlings by 78.7%, 12.7%, 29.8% and 26.5%, respectively. Therefore, intercropping with hyperaccumulator plants can decrease Cd accumulation in grape, and intercropping with S. nigrum can also promote grape seedling growth. [ABSTRACT FROM AUTHOR]