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Yu G.H.,Nanjing Normal University | Li W.,Nanjing Normal University | Yuan Z.Y.,Nanjing Normal University | Cui H.Y.,Nanjing Normal University | And 5 more authors.
Photosynthetica | Year: 2013

We investigated the light reactions, CO2 assimilation, but also the chloroplast ultrastructure in the upper three functional leaves (flag, 2nd, and 3rd leaves) of the Chinese super-high-yield hybrid rice (Oryza sativa L.) Liangyoupeijiu (LYPJ) with ultraviolet-B (UV-B) treatment during reproductive development. Photosynthetic parameters showed that the upper 3 functional leaves of LYPJ entered into senescence approximately 15 days after flag leaf emergence (DAE). Leaves in UV-B treatment exhibited greater efficiency in absorbing and utilizing light energy of photosystem II (PSII), characterized by higher chlorophyll (Chl) content and the whole chain electron transport rate (ETR). However, UV-B radiation reduced activities of Ca2+-ATPase and photophosphorylation. The significantly decreased activity of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) was greatly associated with the decline in photosynthetic efficiency. The net photosynthetic rate (PN) and stomatal conductance (gs) suffered strong reductions before 25 DAE, and afterwards showed no significant difference between control and treatment. UV-B treatment delayed chloroplasts development of flag leaves. Chloroplast membranes later swelled and disintegrated, and more stromal thylakoids were parallel to each other and were arranged in neat rows, which might be responsible for better performance of the primary light reaction. It is likely that accumulation of starch and an increase in the number of lipid droplet and translucent plastoglobuli were results of an inhibition of carbohydrate transport. Our results suggest that long-term exposure to enhanced UV-B radiation was unlikely to have detrimental effects on the absorption flux of photons and the transport of electrons, but it resulted in the decrease of photophosphorylation and Rubisco activation of LYPJ. The extent of the damage to the chloroplast ultrastructure was consistent with the degree of the inhibition of photosynthesis. © 2012 Springer Science+Business Media Dordrecht. Source


Jianxin X.,South China Agricultural University | Jianxin X.,Shenzhen Techand Ecology and Environment Co. | Li X.,South China Agricultural University | Zhiyao S.,South China Agricultural University
Pedosphere | Year: 2016

During January-February 2008, a severe ice storm caused significant damages to forests in southern China, creating canopy gaps and changing soil nutrient availability and enzyme activity. To understand the relationships between gap size, changes in the soil environment and the effects that these changes have on soil processes, we investigated the effects of gap size on soil chemical and biological properties in the forest gaps in a Cunninghamia lanceolata stand in northern Guangdong Province, southern China. Ten naturally created gaps, five large (80-100 m2) and five small (30-40 m2), were selected in the stand of C. lanceolata. The large gaps showed a significant increase in light transmission ratio and air and soil temperatures and a decline in soil moisture, organic matter, N and P compared with the small gaps and the adjacent canopy-covered plots in the 0-10 cm soil. The differences in organic matter and nutrient levels found between the large and small gaps and the canopy-covered plots may be related to changes in environmental conditions. This indicated rapid litter decomposition and increased nutrient leaching in the large gaps. Moreover, the lowest levels of catalase, acid phosphatase and urease activities occurred in large gaps because of the decline in their soil fertility. Large forest gaps may have a region of poor fertility, reducing soil nutrient availability and enzyme activity within the C. lanceolata stand. © 2016 Soil Science Society of China. Source


Yan K.,Yunnan University | Wong M.H.G.,Yunnan University | Wong M.H.G.,CAS Beijing Institute of Geographic Sciences and Nature Resources Research | Zhang L.,Yunnan University | And 8 more authors.
Applied Mechanics and Materials | Year: 2014

Phosphorus leakage from phosphorus-enriched soils (PES) is a major cause of water degradation worldwide, and phytoextraction is known to be an effective method of remediation. However, it is unclear whether phytoextraction is equally efficient in mountainous regions. We investigated the potential of P accumulation of major plant species in the Lake Dianchi Watershed of Southwestern China. Most of the plants living in PES of this region have high P contents; some have been identified as P-hyperaccumulators, such as Polygonum pubescens, which has the highest leaf P content of 16.88 mg/g. Although the dominate species have relatively low P contents than the P-hyperaccumulators, they still have a higher P uptake potential due to their greater biomass, for example, the P uptake potentials of Alnus nepalensis, Coriaria nepalensis, and Erianthus rufipilus are 46.98, 16.91, and 22.78 kg/ha, respectively. While these plants can decrease the total P of rhizospheric soil and topsoil, the effects on the total P-pool was not significant. Our results suggest that just phytoextraction may be less efficient in remediating PES in mountainous regions, and it requires further studies about P cycling and native plants to design more effective measures for P immobilization. © (2014) Trans Tech Publications, Switzerland. Source


Xu X.-J.,Peking University | Xu X.-J.,Shenzhen Techand Ecology and Environment Co. | Sun J.-Q.,Peking University | Nie Y.,Peking University | Wu X.-L.,Peking University
Chemosphere | Year: 2015

In situ remediation of organic contaminants via physical, chemical, and biological approaches is a practical technique for cleansing contaminated water and soil. In the present study, we showed that the three bacterial strains Pseudomonas sp. E1, Klebsiella terrigena E42, and Pseudomonas sp. E46, which can infect and colonize the aquatic plant Spirodela polyrhiza, utilize fenpropathrin as the sole carbon source for growth. S. polyrhiza helped enhance fenpropathrin degradation by E46 by 17.5%, only slightly improved fenpropathrin degradation by E42, and had no effect on strain E1. The application of plant exudates and extracts from fenpropathrin-unexposed/induced plants stimulated bacterial growth of the three strains, but resulted in differential fenpropathrin degradation, suggesting that not all plants and their endophytic bacteria are suitable for coupling phytoremediation and microbial-remediation. Moreover, addition of soil sediments to a microcosm not only stimulated the growth of strain E46 but also increased the rate of fenpropathrin degradation. © 2015 Elsevier Ltd. Source


Huang D.,Shenzhen Techand Ecology and Environment Co. | Liu S.,Shenzhen Techand Ecology and Environment Co. | Zhou X.,Shenzhen Techand Ecology and Environment Co. | Qian D.,Shenzhen Techand Ecology and Environment Co. | And 2 more authors.
Acta Horticulturae | Year: 2012

Trunk spiral girdling was carried out on six years old litchi (Litchi chinensis Sonn. 'Nuomici' and 'Guiwei') trees which poorly fruiting during the early flower bud differentiation phase (about early December). A 1.2 to 1.8 spiral circle with a width of 0.2 to 0.4 cm and a spiral angel of 16-19 degrees was extended into the xylem of the trunk or branch. The wound was almost healed at harvesting time. Compared with the control (no girdling), the ratio of fruit-setting plants was 55.3, 64, 74.7, 78, 74 and 73.3% higher in cultivar 'Nuomici', and 58, 62.7, 68.7, 73.3, 70 and 65.4% higher in cultivar 'Guiwei' in 2000, 2001, 2002, 2003, 2004 and 2005, respectively. Yield per plant was 2.5, 4.2, 6.5, 9.2, 13.5 and 16.5 kg higher in cultivar 'Nuomici', and 2.4, 3.8, 5.5, 8.9, 13.9 and 14.8 kg higher in cultivar 'Guiwei', respectively. The plants with spiral girdling fruited 6 years early than control. Total sugar concentration in fruit of plant with spiral girdling was 3.5 and 2.1% higher than those in control, while total acid concentration was 0.7 and 0.4% lower than those in control in cultivars 'Nuomici' and 'Guiwei', respectively. Source

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