Effect of root exudates of intercropping Vicia faba and Arabis alpina on accumulation and sub-cellular distribution of lead and cadmium.

A field experiment in which a hyperaccumulator (Arabis alpina) was intercropped with winter crop (Vicia faba), was conducted to understand effect of the root exudates on the content and accumulated amounts, sub-cellular distribution of Cd and Pb of the intercropped plants during the ripening period of V. faba (120 d after sowing). The results showed that contents of soluble sugars exuded from the roots of intercropped A. alpina were 67.6% less than that of the monocropped plant, whereas contents of free amino acids was 57.9% greater. The total contents of organic acids exuded from roots of intercropped A. alpina and V. faba were 578.8% and 37.8% greater than that of monocropped plants, respectively. The contents of tartaric acid and malic acid exuded by roots of intercropped A. alpina were greater 31.9 times and 15.9 times than those of monocropped A. alpina, respectively. The contents and accumulated amounts of Cd and Pb in intercropped A. alpina were greater than those of monocropped A. alpina. The contents of Pb bound to organic matter in cell walls, cytoplasm and organelles of intercropped plants were greater than those of monocropped plants. These results demonstrate that increases in accumulated amounts of Pb and Cd caused by intercropping were closely related to migration of Cd and Pb in plants mediated by the composition and content of the root exudates.

[Mechanism of As(â ¤)Removal from Water by Lanthanum and Cerium Modified Biochars].

Loaded lanthanum or cerium biochars were prepared by one step pyrolysis of La (NO3)3-laden or Ce (NO3)3-laden rice hulls and were employed for enhancing the adsorption of As (Ⅴ) from water. In contrast with BC and Ce-BC in this study, La-BC had better adsorption capacity in the acidic condition. The maximum adsorption capacity could reach 20.1 mg ·g-1. With increased pH, the adsorption capacity of La-BC was reduced. The highest adsorption capacity reached 39.1 mg ·g-1 (pH=5) and the lowest was 17.6 mg ·g-1 (pH=9). The resulting La-BC with As (Ⅴ) adsorption was characterized by SEM-EDS, FTIR, and XPS. There were two types of active adsorption sites for As (Ⅴ), oxygen-rich functional groups and lanthanum oxide. Although Ce-BC had oxygen-rich functional groups and cerium oxide, it was unable to participate in the adsorption of As (Ⅴ) from water.

[Source Apportionment of Heavy Metals in Farmland Soils Around Mining Area Based on UNMIX Model].

Forty-two farmland soil samples were collected from the mining area of Huize City, Yunnan Province, to identify the sources of metals in the farmland soils, and 14 selected elements in farmland soils were detected. The UNMIX model was applied to identify the sources of the metals. The inverse distance weighted interpolation method of statistical analysis in ArcGIS was used to develop a spatial distribution map of the six severely polluted metals to validate the source apportionment results of the UNMIX model. The results indicated that:① the metals, Pb, Zn, and Cd, in the studied farmland soils were seriously polluted according to the soil background values of Yunnan Province and the Chinese environmental quality standard; ② there were three potential sources of metals according to UNMIX model:source 1 was the anthropogenic sources caused by industrial activities with a source contribution rate of 16.32%; source 2 was the anthropogenic sources caused by coal combustion and fertilization with a source contribution rate of 68.26%; and source 3 was the combined sources caused by mining related activities and soil parent materials with a source contribution rate of 15.42%; and ③ the spatial distribution of selected metals was in accordance with the local land-use and the results of the UNMIX model. Therefore, the UNMIX model can be effectively applied to the source apportionment of heavy metals in farmland soils around the mining area.

[Effects of As stress on contents of saponin and flavonoid, key enzymes activities of Panax notoginseng and its proteomic analysis]. / ç ·èƒè¿«å¯¹ä¸‰ä¸ƒçš‚è‹·å’Œé»„é ®å«é‡ã€å ³é”®é ¶æ´»æ€§çš„å½±å“åŠå ¶è›‹ç™½è´¨ç»„åˆ†æž.

Field plot experiments were conducted to study the effect of two-year consecutive As stress [As(V): 0, 20, 80, 140, 200 and 260 mg·kg-1] on contents of As, saponin and flanovoids, the enzyme activities of phenylalanine ammonia lyase (PAL), chalcone synthase (CHS), and squalene synthase (SS) in main root, fibrous root and rhizome and shoot, and proteome of three-year old Panax notoginseng in Wenshan prefecture, Yunnan Province, China. The results showed that total saponin content of fibrous root decreased with increase in As treatment concentration. Total saponin contents of shoot and rhizome increased with 140 mg·kg-1 As treatment compared with control. SS activity of rhizome was higher than that of shoot. Flavonoid contents of diffe-rent plant parts decreased with increase in As treatment concentration. With 140 mg·kg-1 As treatment, activities of PAL and CHS in rhizome were higher than that in shoot. CHS activities in shoot and rhizome were lower, and PAL activities were higher than those of the control. As contents in different plant parts of P. notoginseng increased with increase in As treatment concentration. The highest As content was observed in fibrous root. With 140 mg·kg-1 As treatment, twenty-one diffe-rential proteins (ratio >2, P<0.05) were identified in the inoculated compared to the control. The down-regulated proteins included phosphoribulokinase, heat shock protein, NAD(P)-binding rossmann-fold superfamily proteinisoform, monodehydroascorbate reductase and cytochrome b6-f complex iron-sulfur subunit. The up-regulated proteins included CDC27 family protein, acidic endochitinase isoform, symbiosis receptor-like kinase precursor, isoflavone reductase-like protein, phospho-2-dehydro-3-deoxyheptonate aldolase, putative protein kinase superfamily protein, malate dehydrogenase, glyoxalase I isoform and glutamine synthetase cytosolic isozyme. In general, with two-year consecutive As stress, As contents in different plant parts of P. notoginseng increased, which not only affected the photosynthesis and energy, but also decreased the antioxidation and resilience, and induced the increased expression of protein involved in detoxication, resulted in decrease in the contents of flavonoid and saponin. The tolerant threshold value of P. notoginseng for As was 140 mg·kg-1.

[Effects of enhanced UV-B radiation on culm charateristics and lodging index of two local rice varieties in Yuanvang terraces under field condition].

Two local rice varieties (Baijiaolaojing and Yuelianggu) were cultivated in situ in Yuanyang terraces, China, in 2012 and 2013 to investigate the effect of enhanced UV-B radiation condition (0, 2.5, 5.0 and 7.5 kJ . m2) on internode characteristics including length, culm diameter, culm wall thickness from the first to the fourth internode, as well as the lodging index. The results showed that UV-B radiation had no significant influence on internode length and culm, but significanly reduced the culm wall thickness, with that of the fourth internode region decreased by 11.6% to 19.6% under 7.5 kJ . m2 UV-B radiation. The enhanced UV-B radiation increased the lodging index of rice varieties, making them more prone to lodging. The fourth internode had the highest lodging index which was higher than the lodging critical value (200). The decrease in culm wall thickness due to the enhanced UV-B radiation could be responsible for the increasing lodging risk of rice varieties grown in Yuanyang terraces.

[Physiological differences and their genetic backgrounds of Erigeron breviscapus populations under enhanced UV-B radiation].

A simulation experiment was conducted under greenhouse condition to study the effects of enhanced UV-B radiation (280-320 nm) on the flavonoid and MDA contents and antioxidant enzyme activities of six Erigeron breviscapus populations, and the intraspecific differences in physiology to the UV-B radiation. The related genetic backgrounds of E. breviscapus populations were also analyzed by ISSR analysis. Under enhanced UV-B radiation, the flavonoid content of E. breviscapus populations D01, D53, D63 and D65 increased significantly at seedling, flowering, and maturing stages, and the MDA content decreased significantly at seedling and flowering stages; while the flavonoid content of D47 and D48 increased significantly at flowering stage but decreased at maturing stage, and the MDA content increased significantly at the three growth stages. The POD and APX activities of D01 at the three growth stages, CAT activities at seedling and flowering stages, and SOD activity at flowering stage significantly increased; the SOD, CAT and APX activities of D47 at the three growth stages and the POD activity at maturing stage decreased significantly; the POD and APX activities of D48 at the three growth stages and the SOD activity at seedling and maturing stages decreased significantly; the SOD and APX activities of D53 at seedling and flowering stages and the CAT activity at flowering stage increased significantly; the SOD, POD and APX activities of D63 at the three growth stages increased significantly; and the CAT and APX activities of D65 at maturing stage had no significant changes, but the test enzyme activities at the three growth stages increased significantly. D01, D53, D63, and D65 were tolerant to UV-B radiation, while D47 and D48 were sensitive to UV-B radiation. The responses of E. breviscapus populations to enhanced UVB radiation varied with growth stage, being in the order of flowering stage > seedling stage > maturing stage. There was an obvious genetic polymorphism among the six E. breviscapus populations, which were divided into two groups at the level of 0.11 of genetic distance, one group including D01, D53, D63 and D65, and the other including D47 and D48. This classification was consistent with the results of physiological response index to UV-B radiation.