Ming’an Liao

Intercropping different varieties of radish can increase cadmium accumulation in radish

Genetic diversity has supplied effective ways to improve crop yields and disease resistance. Therefore, crop uptake of heavy metals may be reduced by collecting germplasm resources. In the present study, cadmium accumulation and nutrients in radish were investigated by intercropping 3 genotypes (red, green, and white radish) in different combinations. Both pot and field experiments showed that cadmium content in radish was increased by intercropping 2 or 3 genotypes, except when white radish was intercropped with green radish. The biomass of red radish was improved by a mixture of all 3 genotypes, green radish biomass was improved by intercropping with the other 2 varieties, and white radish biomass was improved by intercropping with red radish in both pot and field experiments. The pot experiment indicated that the soil exchangeable cadmium concentration of red radish grown with green radish was lower than that of monoculture, whereas red radish intercropped with white radish was between the respective monocultures; the soil exchangeable cadmium concentrations of green radish grown with white radish and with all 3 genotypes grown together were greater than those of the monocultures. Some intercropping modes also improved potassium and phosphorus contents in the edible parts of radish in the pot experiment.

Screening of a new cadmium hyperaccumulator, Galinsoga parviflora , from winter farmland weeds using the artificially high soil cadmium concentration method

A new method, the artificially high soil cadmium (Cd) concentration method, was used to screen for Cd hyperaccumulators among winter farmland weeds. Galinsoga parviflora was the most promising remedial plant among 5 Cd accumulators or hyperaccumulators. In Cd concentration gradient experiments, as soil Cd concentration increased, root and shoot biomass decreased, and their Cd contents increased. In additional concentration gradient experiments, superoxide dismutase and peroxidase activities increased with soil Cd concentrations up to 75 mg kg(-1) , while expression of their isoenzymes strengthened. Catalase (CAT) activity declined and CAT isoenzyme expression weakened at soil Cd concentrations less than 50 mg kg(-1) . The maxima of Cd contents in shoots and roots were 137.63 mg kg(-1) and 105.70 mg kg(-1) , respectively, at 100 mg kg(-1) Cd in soil. The root and shoot bioconcentration factors exceeded 1.0, as did the translocation factor. In a field experiment, total extraction of Cd by shoots was 1.35 mg m(-2) to 1.43 mg m(-2) at soil Cd levels of 2.04 mg kg(-1) to 2.89 mg kg(-1) . Therefore, the artificially high soil Cd concentration method was effective for screening Cd hyperaccumulators. Galinsoga parviflora is a Cd hyperaccumulator that could be used to efficiently remediate Cd-contaminated farmland soil.

Effects of Mulching Tolerant Plant Straw on Soil Surface on Growth and Cadmium Accumulation of Galinsoga parviflora

Pot and field experiments were conducted to study the effects of mulching with straw of cadmium (Cd) tolerant plants (Ranunculus sieboldii, Mazus japonicus, Clinopodium confine and Plantago asiatica) on growth and Cd accumulation of Galinsoga parviflora in Cd-contaminated soil. In the pot experiment, mulching with M. japonicus straw increased the root biomass, stem biomass, leaf biomass, shoot biomass, plant height and activities of antioxidant enzymes (superoxide dismutase, peroxidase and catalase) of G. parviflora compared with the control, whereas mulching with straws of R. sieboldii, C. confine and P. asiatica decreased these parameters. Straws of the four Cd-tolerant plants increased the Cd content in roots of G. parviflora compared with the control. However, only straws of M. japonicus and P. asiatica increased the Cd content in shoots of G. parviflora, reduced the soil pH, and increased the soil exchangeable Cd concentration. Straw of M. japonicus increased the amount of Cd extraction in stems, leaves and shoots of G. parviflora by 21.11%, 29.43% and 24.22%, respectively, compared with the control, whereas straws of the other three Cd-tolerant plants decreased these parameters. In the field experiment, the M. japonicus straw also increased shoot biomass, Cd content in shoots, and amount of Cd extraction in shoots of G. parviflora compared with the control. Therefore, straw of M. japonicus can be used to improve the Cd extraction ability of G. parviflora from Cd-contaminated soil.

Influence of Berry Heterogeneity on Phenolics and Antioxidant Activity of Grapes and Wines: A Primary Study of the New Winegrape Cultivar Meili (Vitis vinifera L.).

Wine grapes are usually harvested in vineyards when they ripen. However, not all of the berries in a vineyard ripen homogeneously because of different microclimates around the clusters and berries. In this study, the influence of berry heterogeneity on the phenolic content and antioxidant capacity of grapes and wines under a continental monsoon climate was evaluated for a new wine grape cultivar Meili (Vitis vinifera L.). The total phenolic, flavonoid, flavanol, and monomeric anthocyanin contents in the skin and wine significantly increased with grape density; however, there was no significant difference in the seeds between the two lower densities. The highest values of DPPH free radical-scavenging activity, cupric-reducing antioxidant capacity, and hydroxyl radical-scavenging activity in the skin, seed and wine were detected for the densest berries. The sum of individual phenolic compounds in skin, seed and wine increased with berry density, though no significant difference for skin was observed between the two higher density classes. Hence, the chemical components of Meili grapes and wines were positively associated with the berry density at harvest under the continental monsoon climate.

Effects of living hyperaccumulator plants and their straws on the growth and cadmium accumulation of Cyphomandra betacea seedlings

To determine whether the living hyperaccumulator plants and their straws have the same effects on the growth and heavy metal accumulation of common plants, two pot experiments (intercropping experiment and straw mulch experiment) were conducted to study the effects of living hyperaccumulator plants (Solanum photeinocarpum, Tagetes erecta, Galinsoga parviflora and Bidens pilosa) and their straws on the growth and cadmium (Cd) accumulation of common plant Cyphomandra betacea seedlings. Intercropping with T. erecta or B. pilosa promoted the growth of C. betacea seedlings compared with the monoculture, while intercropping with S. photeinocarpum or G. parviflora inhibited that. Intercropping with S. photeinocarpum decreased the Cd contents in the roots and shoots of C. betacea seedlings compared with the monoculture, but intercropping with the other plants did not. In the straw mulch experiment, the straw of S. photeinocarpum or T. erecta promoted the growth of C. betacea seedlings compared with the control, while the straw of G. parviflora or B. pilosa did not. The straw of S. photeinocarpum or T. erecta decreased the Cd contents in the shoots of C. betacea seedlings, and the straw of G. parviflora or B. pilosa increased the shoot Cd contents. Thus, intercropping with S. photeinocarpum and applying S. photeinocarpum or T. erecta straw can reduce the Cd uptake of C. betacea.

Hyperaccumulator straw improves the cadmium phytoextraction efficiency of emergent plant Nasturtium officinale

With the development of economy, the heavy metal contamination has become an increasingly serious problem, especially the cadmium (Cd) contamination. The emergent plant Nasturtium officinale R. Br. is a Cd-accumulator with low phytoremediation ability. To improve Cd phytoextraction efficiency of N. officinale, the straw from Cd-hyperaccumulator plants Youngia erythrocarpa, Galinsoga parviflora, Siegesbeckia orientalis, and Bidens pilosa was applied to Cd-contaminated soil and N. officinale was then planted; the study assessed the effect of hyperaccumulator straw on the growth and Cd accumulation of N. officinale. The results showed that application of hyperaccumulator species straws increased the biomass and photosynthetic pigment content and reduced the root/shoot ratio of N. officinale. All straw treatments significantly increased Cd content in roots, but significantly decreased Cd content in shoots of N. officinale. Applying hyperaccumulator straw significantly increased the total Cd accumulation in the roots, shoots, and whole plants of N. officinale. Therefore, application of straw from four hyperaccumulator species promoted the growth of N. officinale and improved the phytoextraction efficiency of N. officinale in Cd-contaminated paddy field soil; the straw of Y. erythrocarpa provided the most improvement.

Effects of grafting on the cadmium accumulation characteristics of the potential Cd-hyperaccumulator Solanum photeinocarpum

The effects of grafting on the cadmium (Cd) accumulation characteristics of the potential Cd-hyperaccumulator Solanum photeinocarpum were studied under Cd stress in our experiment. Four treatments were used in the experiment: ungrafted (UG), self-rooted grafting by the same S. photeinocarpum seedling (SG), self-rooted grafting by two different development stages of S. photeinocarpum seedlings (DG), and grafting on the rootstock of wild potato (PG). SG and DG decreased the root, scion stem, leaf, whole shoot, and whole plant biomasses compared with UG, but increased the rootstock stem biomass, while only PG increased the root and whole plant biomasses. SG and DG increased the Cd contents in the different organs of S. photeinocarpum compared with UG, while PG decreased the Cd content compared with UG. The Cd extraction by the whole plant of S. photeinocarpum was ranked as DG > SG > UG > PG. Additionally, the antioxidant enzyme activities in SG and DG were enhanced compared with UG, while that of PG was reduced compared with UG. The grafting increased the DNA methylation levels and changed the methylation patterns of S. photeinocarpum compared with UG. Therefore, SG and DG can increase the Cd accumulation in S. photeinocarpum, which can be used for the phytoremediation of Cd-contaminated soil.

Melatonin affects the growth and cadmium accumulation of Malachium aquaticum and Galinsoga parviflora

ABSTRACT Phytoremediation technology has become one of the main techniques for remediating soils polluted by heavy metals because it does not damage the environment, but heavy metal-tolerant plants have the disadvantages of low biomass and slow growth. A pot experiment was conducted to study the effects of melatonin (Mel) on growth and cadmium (Cd) accumulation in the Cd accumulator Malachium aquaticum and hyperaccumulator Galinsoga parviflora by spraying different concentrations of Mel on them. The results showed that shoot biomass, photosynthetic pigment content and antioxidant enzyme activity were increased in both species after Mel was sprayed on their leaves. Mel reduced the Cd content in shoots of M. aquaticum and increased it in those of G. parviflora. In general, Cd accumulation was greatest in M. aquaticum when Mel was 200 μmol L−1 (120.71 μg plant−1, increased by 15.97% than control) and in G. parviflora when Mel was 100 μmol L−1 (132.40 μg plant−1, increased by 68.30% than control). Our results suggest it is feasible to improve the remediation efficiency of lightly Cd-contaminated soil by spraying G. parviflora with100 μmol L−1 Mel.

Effects of mutual intercropping on cadmium accumulation by the accumulator plants Conyza canadensis, Cardamine hirsuta, and Cerastium glomeratum

ABSTRACT In this study, three cadmium (Cd) accumulator species (Conyza canadensis, Cardamine hirsuta, and Cerastium glomeratum) were co-cultured in Cd-contaminated soil in pots to study the effects of intercropping on co-remediation. Only C. canadensis intercropped with C. glomeratum, C. hirsuta intercropped with C. glomeratum, and three-species intercropping increased plant biomass compared with their respective monocultures. The treatments of C. canadensis intercropped with C. glomeratum and three-species intercropping increased the Cd contents in roots and shoots of C. canadensis, whereas the other intercropping treatments decreased or had no significant impact on Cd contents. As for Cd accumulation, the treatments of C. canadensis intercropped with C. glomeratum, C. hirsuta intercropped with C. glomeratum, and three-species intercropping increased Cd accumulation in a single plant compared with that of their respective monocultures, whereas other intercropping treatments decreased Cd accumulation in individual plants. Only the treatments of C. canadensis intercropped with C. glomeratum and C. hirsuta intercropped with C. glomeratum increased Cd accumulation in shoots of a single pot compared with that of their respective monocultures. Therefore, C. canadensis intercropped with C. glomeratum and C. hirsuta intercropped with C. glomeratum may improve the phytoremediation efficiency for Cd-contaminated soil.

Effects of mutual intercropping on the cadmium accumulation in accumulator plants Stellaria media, Malachium aquaticum, and Galium aparine

Intercropping affects heavy-metal uptake in plants. In this study, three cadmium (Cd)-accumulator species (Stellaria media, Malachium aquaticum, and Galium aparine) were intercropped together in Cd-contaminated soil to study the effects of intercropping on co-remediation. Mutual intercropping significantly increased the biomasses of S. media, M. aquaticum, and G. aparine compared with their respective monocultures. The photosynthetic pigment contents of three species were not significantly affected by mutual intercropping. Mutual intercropping did not increase the Cd contents in roots and shoots of G. aparine, but it increased the Cd contents in roots of S. media and M. aquaticum. It also decreased the Cd contents in shoots of S. media and M. aquaticum. Only G. aparine intercropped with M. aquaticum and three-species intercropping increased Cd-accumulation levels in whole plants of each species. Only S. media intercropped with M. aquaticum and three-species intercropping increased the Cd accumulation at the whole plant level in every plant in a single pot, with S. media intercropped with M. aquaticum showing the greatest increase. Therefore, S. media intercropped with M. aquaticum and three-species intercropping may improve the efficiency of phytoremediation of Cd-contaminated soil, with S. media intercropped with M. aquaticum representing the best combination.