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Abscisic acid (ABA) is an important hormone that can regulate the heavy-metal uptake of plants. In this study, exogenous ABA was applied to lettuce (Lactuca sativa) grown under cadmium (Cd)-stress conditions, and the effects of exogenous ABA on the growth and Cd accumulation of lettuce were evaluated. The results showed that treatment of Cd significantly decreased biomass and increased Cd content of lettuce compared with the control. The shoot biomass increased after spraying 1, 5 and 10 μmol/L ABA, and the root biomass increased after spraying 1–20 μmol/L ABA compared with the treatment of Cd. The Cd content in shoots significantly decreased when exposed to different ABA concentrations. The lowest Cd content in shoots of lettuce was produced by the ABA concentration of 5 μmol/L, with decreased by 23.60% compared with the treatment of Cd. Therefore, spraying ABA effectively alleviated Cd toxicity and reduced Cd uptake in the edible parts of lettuce, and 5 μmol/L ABA was the optimal dose. [ABSTRACT FROM AUTHOR]

Improvement of selenium (Se) uptake in fruit tree can improve the source of food Se for humans. In this study, the effect of various abscisic acid (ABA) concentrations on the Se uptake in Cyphomandra betacea Sendt. (Solanum betaceum Cav.) seedlings was studied under Se stress. Only the concentration of 20 μmol/L ABA promoted the growth of C. betacea seedlings by increasing the biomass and regulating the resistance physiology under Se stress. ABA also increased the Se content in C. betacea seedlings under Se stress. The concentration of ABA at 20 μmol/L got the maximum root Se and shoot Se contents, which increased by 76.64% and 55.83%, respectively, compared with the control. Correlation and grey relational analyses showed that the peroxidase activity and proline content had the first two closest relationship with the shoot Se content. This study shows that ABA can promote the Se uptake in C. betacea under Se stress, and the concentration of 20 μmol/L ABA is the optimum for Se uptake and growth of C. betacea. Under selenium (Se) stress, abscisic acid (ABA) promotes the Se uptake in Cyphomandra betacea Sendt. (Solanum betaceum Cav.) seedlings, but only the concentration of 20 μmol/L ABA promotes the growth of C. betacea seedlings. The shoot Se content is most closely correlated with the peroxidase activity and proline content. This study shows that ABA can promote the Se uptake in C. betacea under Se stress [ABSTRACT FROM AUTHOR]

In this study, pot experiments were conducted to study the effects of reciprocal grafting on the growth and Cd accumulation in post-grafting generations of two cherry tomatoes – red (Red cherry 5-5-1-1) and yellow (RTY-3-2) cherry tomatoes. Six treatments, which consisted of ungrafted red cherry tomato (R-CK), ungrafted yellow cherry tomato (Y-CK), red cherry tomato as rootstock (R-rootstock), red cherry tomato as scion (R-scion), yellow cherry tomato as rootstock (Y- rootstock), and yellow cherry tomato as scion (Y-scion) were utilised. The results showed that grafting significantly decreased the root biomass of Y- rootstock and Y-scion as compared to that of Y-CK, but there were no differences in the shoot biomass. Compared with that of Y-CK, grafting increased the root Cd content of the post-grafting generations, specifically, Y- rootstock and Y-scion increased by 54.44% and 52.96%, respectively. There were no significant differences in the shoot Cd content of Y- rootstock, Y-scion, and Y-CK. The root, stem, leaf, and shoot biomass of R-rootstock increased by 14.17%, 76.23%, 36.47%, and 21.72%, respectively, as compared with that of R-CK. However, grafting had no significant effect on the root, stem, leaf, and shoot biomass of R-scion. Grafting significantly increased the root Cd content of R-rootstock. However, grafting significantly decreased the shoot Cd content of R-rootstock, with the value 26.18% lower than that of R-CK. The root Cd content of R-scion significantly increased compared with the R-CK, and the shoot Cd content had no differences. Therefore, the reciprocal grafting of the two cherry tomatoes promoted the growth and reduced the Cd uptake of R-rootstock. Findings from this study could be used to provide a reference for the safe production of tomatoes in heavy metal-contaminated soils. [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]

To study the cadmium (Cd)-accumulation characteristics of the post-grafting generation of Cyphomandra betacea (Cav.) Sendt., the seeds of C. betacea grafted on Solanum nigrum L., tomato, and eggplant rootstocks were collected and planted in Cd-contaminated soil. Compared with seeds of ungrafted seedlings, the S. nigrum rootstock increased the shoot biomass of the post-grafting generation of C. betacea seedlings, while eggplant and tomato rootstocks decreased or had no significant effects. Only the S. nigrum rootstock increased the chlorophyll a content, net photosynthetic rate, and stomatal conductance of the post-grafting generation of C. betacea seedlings, while the other rootstocks decreased or had no significant effects on these photosynthetic parameters. The S. nigrum rootstock enhanced the superoxide dismutase and catalase activities, and soluble protein content, of the post-grafting generation of C. betacea seedlings, while the other rootstocks reduced or had no significant effects on these parameters. The three rootstocks decreased the Cd contents in different organs of the post-grafting generation of C. betacea seedlings, and the order of treatments was ungrafted > tomato rootstock > eggplant rootstock > S. nigrum rootstock. Therefore, S. nigrum was the best rootstock to promote the growth and decrease the Cd contents in post-grafting generation of C. betacea, and this can benefit C. betacea production in Cd-contaminated areas. [ABSTRACT FROM AUTHOR]

To study the effects of hyperaccumulator straw application on the growth and cadmium (Cd) accumulation of accumulator Perilla frutescens, four hyperaccumulator plant straws (Youngia erythrocarpa, Galinsoga parviflora, Gnaphalium affine and Crassocephalum crepidioides) were mulched on the surface of a Cd-contaminated soil (10 mg/kg) and P. frutescens seedlings were planted. The Y. erythrocarpa, G. affine and C. crepidioides straws increased P. frutescens root and shoot biomasses, and its chlorophyll a, carotenoid and total chlorophyll contents, whereas G. parviflora decreased or had no significant effect on these parameters. The G. affine and C. crepidioides straws enhanced the superoxide dismutase and catalase activities, and increased the Cd contents in roots and shoots of P. frutescens, whereas Y. erythrocarpa and G. parviflora straws had a smaller increasing effect. The Y. erythrocarpa, G. affine and C. crepidioides straws increased Cd extraction by P. frutescens shoots by 13.44%, 51.96% and 55.67%, respectively, compared with the control, whereas G. parviflora straw decreased it. Therefore, mulching with Y. erythrocarpa, G. affine and C. crepidioides straws could promote P. frutescens growth and enhance its phytoremediation ability for Cd-contaminated soil, with a better effect for G. affine and C. crepidioides straws than Y. erythrocarpa straw. [ABSTRACT FROM AUTHOR]

To study whether grafting can reduce the heavy metal uptake of Cyphomandra betacea, C. betacea seedlings were grafted onto three different rootstocks (eggplant, Solanum nigrum, and tomato) and planted in cadmium (Cd)contaminated soil. Compared with ungrafted seedlings, S. nigrum rootstock increased the biomass of different organs of C. betacea seedlings, while eggplant and tomato rootstocks decreased it or had no significant effect. Chlorophyll a, chlorophyll b, and total chlorophyll contents of C. betacea seedlings were ranked as follows: S. nigrum rootstock > ungrafted > eggplant rootstock > tomato rootstock. The three rootstocks had no significant effects on the superoxide dismutase activity of C. betacea seedlings. Solanum nigrum rootstock enhanced the peroxidase and catalase activities and soluble protein content of C. betacea seedlings, while the other rootstocks reduced or had no significant influence on these parameters. The three rootstocks increased the Cd content of aboveground organs of C. betacea seedlings as follows: S. nigrum rootstock > eggplant rootstock > tomato rootstock > ungrafted. Grafting onto S. nigrum rootstock can therefore promote the growth of C. betacea; however, all rootstocks investigated in this study promote Cd uptake in C. betacea and thus cannot be used in Cd-contaminated areas. [ABSTRACT FROM AUTHOR]

To enhance the phytoremediation ability of the heavy metal accumulator Perilla frutescens, melatonin (MT) was applied at different concentrations (0, 25, 50, 100, 150, and 200 μmol/L) to P. frutescens growing in cadmium (Cd) contaminated soil (10 mg/kg). The MT treatments increased the root and shoot biomasses of P. frutescens, with the maximum increase in the 150 μmol/L MT treatment (79.51% and 36.18% higher, respectively, than those of the control). The MT treatments also enhanced superoxide dismutase activity, peroxidase activity, and the soluble protein concentration of P. frutescens, and 100–200 μmol/L MT increased the chlorophyll a, chlorophyll b, and total chlorophyll concentrations in P. frutescens. The MT treatments increased the Cd concentrations in roots and shoots of P. frutescens in a dose-dependent manner. Different MT concentrations increased the Cd accumulation amounts of roots and shoots of P. frutescens, with the maxima accumulation amounts in the 150 μmol/L MT treatment (226.98% and 85.89% higher, respectively, than those of the control). These results show that MT can promote the growth and phytoremediation ability of P. frutescens growing in Cd-contaminated soil, and the optimum MT dose is 150 μmol/L. [ABSTRACT FROM AUTHOR]