Chinese Pakchoi Research Articles

Greenhouse Characterization of Inorganic Mercury, Methyl Mercury and Ethyl Mercury Migration and Transformation in Indian Mustard and Chinese Pakchoi

Soil mercury (Hg) contamination has long been a problem that threatens the environment and organisms. Thus, exploring the migration and transformation of Hg from soil to vegetable is vital. In this study, different Hg solutions were employed in greenhouse experiments. The Hg contents in soil and vegetable samples were determined by inductively coupled plasma – mass spectrometry. The results showed that the Hg accumulation depended on its concentration and form. A greater accumulation of inorganic Hg was observed in the roots (2.2–27.4 mg/kg) than in the aerial parts (0.6–6.0 mg/kg). A similar trend was also found in the methyl mercury (MeHg) and ethyl mercury (EtHg) irrigated groups. The MeHg contents were 0.7–8.0 μg/kg in roots and 0.1–3.7 μg/kg in aerial parts. The EtHg concentrations were 0.5–3.3 μg/kg in roots and 0.3–1.1 μg/kg in aerial parts. The translocation factors of inorganic Hg and organic Hg for both vegetables in most treatments were less than 0.5, which suggested that Hg primarily accumulated in the roots. The biological concentration factors of inorganic Hg were less than 0.4, and those for MeHg and EtHg were between 0.4 and 0.95, which indicated that the vegetables were more likely to absorb organic Hg from the soil. The methylation of inorganic Hg occurred in the roots. The potential hazards of Hg on food safety and human health must be considered in regions with serious Hg pollution.

Effects of different loading rates and types of biochar on passivations of Cu and Zn via swine manure composting

Pollution of arable land caused by heavy metals in livestock and poultry manure has become a potential threaten to human health in China. Safe disposal of the contained toxic pollution with animal manure by co-composting with biochar is one of the alternative methods. Biochars from different sources (wheat straw, peanut shells and rice husks) amended with different loading rates were investigated for passivations of copper and zinc (Cu and Zn) in swine manure composting. Results showed that the passivation effects of the three types of biochar on Cu and Zn were enhanced with increasing biochar dose. Contents of Cu and Zn measured by diethylenetriaminepentaacetic acid (DTPA) and Community Bureau of Reference (CBR) showed that wheat straw biochar with the loading rates of 10%–13% (w/w) was superior to the other two types of biochar in this study. Compared with the control, sample from wheat straw biochar was more favorable for the bacterial growth of Proteobacteria, Firmicutes and Actinobacteria. In addition, pot experiment showed that organic fertilizer amended with wheat straw biochar could significantly improve the growth of Chinese pakchoi and enzyme activities (superoxide dismutase, peroxidase, polyphenol oxidase and catalase) as compared with the control. Cu and Zn contents of Chinese pakchoi in the organic fertilizer group containing wheat straw biochar reduced by 73.2% and 45.2%, 65.8% and 33.6%, respectively, compared with the group without loading biochar. There was no significant difference in the contents of vitamin C and reducing sugar between the groups of organic fertilizer amended with/without wheat straw biochar, however, there was significant difference compared with the heavy metal addition group. The application of organic fertilizer formed by adding biochar can effectively reduce the adverse effects of heavy metals on crops.

Novel-integrated process for production of bio-organic fertilizer via swine manure composting

The traditional method of producing bio-organic fertilizer contains two consecutive composting stages which, however, is time-consuming and requires high input of energy and cost. This study attempted to combine two consecutive stages into one single step. Paenibacillus polymyxa, as an antagonistic strain to control anthracnose in Chinese Pakchoi, was used as inoculum to obtain bio-organic fertilizers through two approaches: two consecutive stages (TCS) composting as control and the proposed one step through (OST) composting. The resulting two bio-organic fertilizers produced by TCS and OST were tested for the disease incidence and disease resistant index, and the fertility on growth of Chinese Pakchoi. The results of relative abundance of P. polymyxa showed no significant difference between two kinds of bio-organic fertilizers in phylum, family and genus. The disease incidence of bio-organic fertilizers produced by OST and TCS reduced by 61.40% and 68.42%, respectively, as compared to the control group, where the difference was not significant. The growth promoting effect was remarkable, although the difference in the fertility on the growth was not significant. Compared with the traditional TCS method, the novel OST method could improve efficiency of bio-organic fertilizer production by 42.86% per year according to this study.

Adding Phosphate Fertilizer and Apple Waste to Pig Manure during Composting Mitigates Nitrogen Gas Emissions and Improves Compost Quality

Calcium superphosphate and apple ( Mill.) waste can be used for controlling N loss and improving compost quality during composting, whereas integrated addition of the two additives on composting process remains unexplored. Therefore, this study was conducted to investigate the effects of combined use of calcium superphosphate and apple waste on NH and NO emissions and compost quality during pig manure and wheat ( L.) straw composting. Mixtures of pig manure and wheat straw were combined with 6% phosphate fertilizer (PF), 15% apple waste (AW), 3% phosphate fertilizer + 7.5% apple waste (PA1), or 1.8% phosphate fertilizer + 10.5% apple waste (PA2) based on dry weight of the initial mixtures; a treatment with no additives served as a control (CK). The PF treatment took 3 d longer to reach thermophilic phase than the CK, PA1, and PA2 treatments. The treatments of PF and PA1 reduced NH and NO emissions by 67 and 45%, respectively. Moreover, N loss in PF and PA1 treatments (31.8 and 30.1%, respectively) was significantly less than in the CK. A pot experiment showed that application of the compost with PA1 treatment could increase plant height and dried biomass of Chinese pakchoi ( L. ssp.). We recommend adding 3% phosphate fertilizer and 7.5% apple waste to pig manure during composting.

Accumulation of selenium in a Chinese cabbage of a grade Pak-choi in the course of cultivation

Most agricultural areas of Russia have soils poor in mineral selenium, causing higher oncology risks for population of such areas. The way to control malignancy incidence is selenium fortification of soils and plants. This can be achieved by agrochemical enrichment of cultivated plants with nutritive substrates containing essential minerals and trace elements. The current study aimed to assay the effect of inorganic selenium on the rate of Chinese pakchoi cabbage biomass gain for the development of agrochemical techniques for introducing selenium. The optimal selenium introduction technique would demonstrate the best balance of biomass gain rate and selenium ion accumulation in organic matter. Selenium ion accumulation dynamic was assessed during controlled growth of plants in soils enriched with nutritive substrate containing inorganic selenium (potassium selenite). The amount of selenium in plants was determined by spectroscopy. Mathematical functions describing the selenium uptake dynamic of controlled grown plants have been found, including derivatives of these functions that led to obtaining the numerical values of the respective uptake rates. It has been found that agricultural techniques that involve introduction of selenium at intermediate and late stages of cultivation are optimal for plant growth dynamic, as introducing selenium at early stages of cultivation has a negative impact on biomass uptake rates. Additionally, introducing potassium selenite to the nutritive substrate at 1.0 mg×dm–3 proved to be more effective than introducing potassium selenite at 0.5 mg×dm–3 as the former dosage led to a better plant growth dynamic.

Stereoselective uptake and distribution of the chiral neonicotinoid insecticide, Paichongding, in Chinese pak choi (Brassica campestris ssp. chinenesis)

Neonicotinoid chiral insecticidal Paichongding is a promising substitute for the widely used imidacloprid. Four stereoisomers of Paichongding, 5R,7R, 5S,7S, 5S,7R and 5R,7S, were employed in both foliage and roots of Chinese pak choi to investigate their stereoselective uptake and distribution in pak choi. Results showed that after foliar application, no stereoselective absorption into pak-choi plants was observed among the enantiomers. Total absorptions were 35.40% of the applied amount for 5R,7R, 36.66% for 5S,7S, 36.80% for 5S,7R and 38.20% for 5R,7S at 96 HAT. The translocation of the four absorbed stereoisomers within pak choi occurred both acropetally and basipetally and the transport of 14C from enantiomers 5R,7R and 5S,7S were significantly higher than for 5R,7S and 5S,7R. Significant stereoselective translocation inside plants was observed between Paichongding epimers. Total root uptake reached 16.49–19.85% for 5R,7R and 5S,7S, and 24.57–28.82% for 5S,7R and 5R,7S at 144 HAT. Both enantioselective and diastereoselective root uptake into pak-choi occurred between the four stereoisomers. The 5R,7S and 5S,7R enantiomers were more readily uptaken by the roots than 5R,7R and 5S,7S and accumulated in the edible leaves. These results will help to develop an understanding of Paichongding using only the target-active enantiomer of pesticides.