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Seed dispersal distance is influenced by a variety of seed properties and functional responses of dispersers. However, to our knowledge, how and why seed dispersal distances are determined remains poorly understood. In the present study, seeds of sympatric tree species, Pinus koraiensis, Corylus mandshurica, Corylus heterophylla, and Quercus mongolica were released to investigate the effects of rodent abundance, seed type, and seed availability on seed dispersal. Our results showed that seeds of P. koraiensis were dispersed further than those of C. heterophylla and C. mandshurica regardless of the ambient rodent and seed abundances, reflecting a consistent effect of seed type on seed dispersal distances. Seed dispersal distance was greatly facilitated by lower per-capita seed abundance (the ratio of seeds to rodents); however, seed caching and cache survival were benefited from higher per-capita seed abundance. Although seed dispersal and seed caching of a particular tree species can be enhanced by its own seed availability, no consistent influence was detected at interspecific levels, reflecting different interspecific effects of seed availability on seed dispersal of sympatric seed species. Our results provide evidences that the effect of seed availability on seed dispersal should be evaluated in terms of per-capita seed abundance and interspecific effects, rather than the independent influence of seed or disperser abundances.
This study examines differences in the morphophysiological responses of low- and high-cadmium (Cd) accumulating peanut (Arachis hypogaea L.) cultivars to Cd stress. The biomass, Cd accumulation, leaf gas exchange, root morphology, root respiration, and hydraulic conductivity of Qishan 208 (low-Cd accumulator) and Haihua 1 (high-Cd accumulator) were determined via a hydroponic experiment. Exposure of peanut plants to 2 and 20 μM Cd considerably decreased their shoot biomass, net photosynthetic rate, transpiration rate, stomatal conductance, total root length, number of root tips, root respiration, and hydraulic conductivity. The root biomass, root surface area, and average diameter were unaffected by Cd exposure. The two cultivars differed in Cd accumulation and morphophysiological responses to Cd stress. Qishan 208 accumulated less Cd in plant tissues but was more sensitive to Cd stress than Haihua 1. The total root length, surface area, average diameter, number of root tips, and root respiration rate of Haihua 1 were significantly higher than those of Qishan 208. The well-developed root system and higher root respiration of Haihua 1 may be responsible for its high Cd accumulation capacity.
Endosperm cap (CAP) weakening and radicle (RAD) elongation growth are prerequisites for the completion of lettuce seed germination. Lettuce CAP and RAD cell walls contain a large amount of L-arabinofuranose, which may exist in the form of arabinan or L-arabinofuranose- rich polysaccharides. The aim of the present study was to investigate the relationship between a-L-arabinofuranosidase, an enzyme degrading L-arabinofuranose-rich polysaccharides, and CAP weakening and RAD elongation growth. It was shown that the enzyme activity and the transcript abundance of two lettuce α-L-arabinofuranosidase genes, LsARAf2 and LsARAf7, increased in the CAP and RAD prior to the completion of seed germination during imbibition in water. Sodium dichloroisocyanurate, a chemical inducing atypical germination (RAD elongation without endosperm rupture) in lettuce seeds, significantly decreased the enzyme activity and the transcript abundance of LsARAf7 and LsARAf2 in the CAP. It is concluded that the expression of α-L-arabinofuranosidase is necessary for CAP weakening and the suppression of this enzyme in the CAP is at least partly responsible for atypical germination in lettuce.
Background. Though fishes grow indeterminately, very little is known of the effects of age on the morphometric indices (length, weight, and condition) in fishes as it is often difficult to cover the entire lifespan of a species in laboratory or nature. The presently reported study was thus conducted to elucidate the effects of age (and sex) on the growth indices using the annual fish and a laboratory model of aging. Materials and Methods. Experimental fish—the redtail notho, Nothobranchius guentheri (Pfeffer, 1893), were obtained by hatching the diapause eggs of the same parental lineage and reared over their entire lifespan. Length–weight measurements were recorded from 3–12 months and various indices (length–weight relation, Fulton’s condition factor, and relative condition factor) were computed and compared statistically. Results. Mean lengths, weights, length–weight relations (LWRs), Fulton’s condition factor (K) and relative condition factor (Kn) varied significantly leading to differential indices based on age and sex. Age influenced all indices positively, which is indicative of the indeterminate growth typical of fishes. Conclusion. Age was not seen to suppress the growth indices in the annual fish, which is suggestive of a healthy and delayed senescence in the annual fish N. guentheri. Whether other short- and long-lived finfish follow the same pattern needs further investigation.
The acid pre-washing of zero valent iron for improving removal efficiency would deduce the secondary pollution in groundwater, and more fine particles of zero valent iron would reduce the permeability of aquifers. In order to better understand the approaches of nitrate removal, a series of laboratory experiments was conducted in this study. Batch tests showed that washed zero valent iron powder and activated carbon are more efficient for removing nitrate than cemarite and zeolite, similar with the acid pre-washing zero valent iron. X-ray diffraction phase analysis showed that a kind of oxide Fe₃O₄ generated on the surface of the washed iron powder particles, which is mixed with Fe₂O₃ and FeO, is relatively loose and can improve the efficiency of nitrate removal. A continuous flow column system test showed that the coarse sand-zero valent iron mix (R1), the coarse sand-zero valent iron-activated carbon mix (R4), and the coarse sand-zero valent iron-sawdust mix (R5) are more effective for reducing nitrate than the coarse sand-activated carbon mix (R2) and the coarse sand-sawdust mix (R3). Components such as NO₂-N and NH₄⁺-N would have environmental concerns as well. Further chemical analysis on the fluids from nitrate removal treatment indicates that R1 and R4 are the most effective and also environmentally friendly media for nitrate removal. This study showed that R1 and R4 media could be developed into a viable technology for the removal of nitrate in high concentration of polluted groundwater.
The content of four phthalate acid esters (PAEs) in air, soil, plants, organic films, and water of the arid city of Changji, China, was investigated and the concentration distribution and fate was simulated using a multimedia urban model (MUM). Analysis indicated that PAEs are ubiquitous environmental contaminants, with the dominant being DBP and DEHP. The mean PAE concentrations of air, soil, plants, organic films, and water was 5.54×10-7 g/m3, 1.09×10-2 g/m3, 6.57×10-2 g/m3, 0.28 g/m3, and 9.84×10-2 g/m3, respectively. By using MUM, we found that the total residues of PAEs in each environmental medium was 2.61×107 g. The regularity of concentration distribution was organic films > sediment > plants > water > soil >air, and the regularity of total amount distribution was air > soil > water > sediment > plants > organic films. The regularity showed that air and soil were the main sink of PAEs (up to 99.59% of total mass). The reliability of the model was verified by the agreement between the measured and calculated concentrations
Groundwater is considered a major source of drinking water and its quality a basis for good population health. In order to identify groundwater hydro-chemical characteristics and pollution conditions in Songnen Plain, groundwater hydro-chemical characteristics and nitrate-nitrogen (NO3-N) spatial distribution characteristics and the health risks were analyzed. Results showed that groundwater hydro-chemical type was mainly HCO3-Ca, which was associated with the action of calcite and silicate mineral weathering dissolution. The over standards rate of NO3-N accounted for 50.8%, the coeffi cient of variation was 183.57% which was high spatial variability, the high-risk area accounted for 88.78% of the total study area, and the high-risk area covered the area with water quality of classes IV, V, and part of class III. The high-risk area is mainly distributed in the eastern high plains and in the central low plains, while the low-risk zone accounts for only 11.22% of the total area and is mainly distributed in the western alluvial plain with scattered distribution in other areas.
Treating plants with abiotic or biotic factors can lead to the establishment of a unique primed state of defense. Primed plants display enhanced defense reactions upon further challenge with environmental stressors. Here, we report that trivalent chromium (Cr(III)) pretreatment can alleviate hexavalent chromium (Cr(VI)) toxicity in 2-week-old wheat plants. The data indicate that Cr(III)- pretreated wheat displayed longer survival times and less heavy metal toxicity symptoms under Cr(VI) exposure than the control. To investigate the possible mechanism from an antioxidant defense perspective, we determined the H₂O₂ and lipid peroxide content (TBARS), the activities of antioxidant enzymes (SOD, CAT, APX and GR) and the antioxidant metabolite content (ascorbate and glutathione content, AsA/DHA and GSH/GSSG ratios) in pretreated wheat roots. The results showed that 0.5 μM Cr(III) pretreatment can alleviate oxidative damage, such as H₂O₂ and TBARS accumulation, in root tissues compared to the control during the first 3 days of Cr(VI) exposure. Furthermore, we determined that this pretreatment can significantly increase the antioxidant enzyme activities and total ascorbate and glutathione contents compared to the control treatment. In addition, redox homeostasis declined slightly in pretreated wheat compared to the control in the presence of Cr(VI). We discuss a possible mechanism for Cr(III)-mediated protection of wheat.
In order to investigate characteristics of wet deposition of heavy metals in an arid city, precipitation samples were collected for 16 precipitation events in the arid city of Changji. A total of 16 samples were collected and concentrations of principal heavy metals in the atmosphere were examined by inductively coupled plasma-mass spectrometry (ICP-MS) to discuss levels, variation, and wet deposition fluxes of heavy metals. Among these heavy metals in wet deposition, Fe, Zn, and Cu were found to be the highest. Levels of As, Ni, and Cr ranked second, while Pb, Cd, and Hg were found to be the lowest. The concentrations of heavy metals in wet deposition showed distinct seasonal variations, having high values in winter and low values in other seasons. Besides, in general, concentrations of heavy metals in snow were higher than those in rain. Because the winter was cold and long in Xinjiang, emissions from coal-fired heating were high, which was associated with enhanced concentrations of heavy metals. The order of wet deposition fluxes of heavy metals in the whole year was Fe > Cu, Zn > As, Ni, Cr, Pb > Cd, Hg. Compared to other areas, wet deposition fluxes of heavy metals were low in Changji, which may be due to minimal rainfall in the arid city, having a weak scavenging effect of atmospheric pollutants. In addition, because the level of urbanization and industrialization was not high in Changji, emissions of atmospheric pollutants were low.
Stripe rust (caused by Puccinia striiformis) occurs annually in most wheat-growing areas of the world. Thinopyrum ponticum has provided novel rust resistance genes to protect wheat from this fungal disease. Wheat – Th. ponticum partial amphiploid line 7430 and a substitution line X005 developed from crosses between wheat and 7430 were resistant to stripe rust isolates from China. Genomic in situ hybridization (GISH) analysis using Pseudoroegneria spicata genomic DNA as a probe demonstrated that the partial amphiploid line 7430 contained ten Js and six J genome chromosomes, and line X005 had a pair of Js-chromosomes. Giemsa-C banding further revealed that both lines 7430 and X005 were absent of wheat chromosomes 6B. The EST based PCR confirmed that the introduced Js chromosomes belonging to linkage group 6, indicating that line X005 was a 6Js/6B substitution line. Both resistance observation and sequence characterized amplified region (SCAR) markers displayed that the introduced chromosomes 6Js were responsible for the stripe rust resistances. Therefore, lines 7430 and X005 can be used as a donor in wheat breeding for stripe rust resistance.
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