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Abstract: Development and use of ozone (O3)-resistant crop cultivars are key measures to avoid agricultural yield reduction in a high O3 environment. However, little is known about the impacts of breeding methods and breeding sites on the development of O3 tolerance in winter wheat cultivars. To explore such impacts, 20 Chinese winter wheat cultivars bred using four breeding methods (viz. introduction, reselection, conventional breeding and hybridization) at four breeding sites having different levels of O3 exposures, were exposed to charcoal-filtered (CF) air or high O3 (82ppb, 7hd−1) for 21 days. O3 tolerance of cultivars was assessed by the relative levels of visible injury, growth, gas exchange, dark respiration, antioxidative activities and oxidative modification of proteins and cellular membranes. We found that conventional breeding and hybridization demonstrated higher potential capacity for O3 tolerance as indicated by a higher level of ascorbate and peroxidase activity in cultivars exposed to CF air. Despite the highest potential capacity for O3 tolerance, hybridization displayed the lowest O3 tolerance as represented by antioxidative activities, oxidative stress, photosynthesis and growth. The causes of higher O3 sensitivity in hybrid cultivars included lower O3 exclusion by stomatal closure, higher reduction in antioxidative activities, higher O3-induced modification of proteins and cellular membranes, lower level of repair of O3-induced cellular damage and higher loss of assimilation rate as well as growth in O3 relative to control plants. Cultivars bred at breeding sites experiencing higher ambient O3 exposures demonstrated higher potential capacity for O3 tolerance. The observed O3 tolerance in cultivars bred by different breeding methods was uncorrelated to ambient O3 levels in breeding sites as well as to the potential O3 tolerance capacity as observed in CF air. Results from our experiment, therefore, clearly indicated that potential O3 sensitivity would have little use in predicting actual O3 tolerance of winter wheat cultivars. Our findings also suggested that sensitivity to O3 in winter wheat cultivars was related to breeding methods, but not to O3 concentrations in breeding sites. [Copyright &y& Elsevier]

This paper presents the potential for energy savings in various capacity sponge iron plants by estimating heat transfer rates using stabilized and optimized temperature data within the rotary kiln/reactor. Air jet seal instead of mechanical seal arrangements at specific locations in the rotary kiln and cooler are proposed and this is shown to reduce the power consumption and the size of the centralized grease lubricating system. The paper proposes atomized water spray on the post combustion chamber instead of larger droplets to reduce the size of the water handling system, thereby saving energy. The paper also suggests optimization of the performance of a pneumatic coal injector by optimizing coal and air quantities. [ABSTRACT FROM AUTHOR]

Abstract: In order to explore the response patterns of gas exchange to the increased grazing intensity and to test whether or not plants have compensatory growth under animal grazing disturbance, we have conducted this experiment in Hunshandak Sandland of Northern China. Changes in net photosynthetic rate (Pn), transpiration rate (E), and water use efficiency (WUE) of four plant species (Cleistogenes squarrosa, Agropyron cristatum, Artemisia frigida, Potentilla acaulis) in four grazing intensities, non-, light-, moderate- and high-grazed plots were investigated. Pn of all four species increased from non-grazed plots to moderate-grazed plots then decreased under high-grazed conditions. However, P. acaulis increased its Pn from moderately grazed plots to high-grazed plots, suggesting a strong compensatory photosynthetic growth. Transpirations of the four species elevated considerably with the increase of grazing intensity. Except for Artemisia frigida, WUE of others increased significantly from non-grazed plots to moderately grazed plots then decreased in high-grazed plots. Our results indicate that, while a sharp decrease in leaf areas and aboveground biomass, photosynthetic growth and WUE were enhanced under moderate level of grazing. With a level of grazing increased, the plant functions were declined as a result. Therefore, grassland in Hunshandak Sandland fails to support the present stocking rate. [Copyright &y& Elsevier]

Abstract: Experiments were conducted to investigate the photosynthetic activity and thermostability of photosystem II (PSII) in elm seedling (Ulmus pumila) leaves from initiation to full expansion. During leaf development, photosynthesis, measured as CO2 fixation, increased gradually and reached a maximum value when leaves were fully developed. In parallel with the increase of carbon assimilation, chlorophyll content increased. The chlorophyll a fluorescence measurements showed that the maximum quantum yield of PSII primary photochemistry (φ po), the efficiency with which the energy of trapped excitons is converted into the electron transport beyond Q A (Ψ o) and the quantum yield of electron transport beyond Q A (φ Eo) increased gradually. The low light experiments confirmed these results independently. When subjected to heat stress, young leaves exhibited progressively lower φ po and maximal fluorescence (F m) values with considerably higher minimal fluorescence (F o) than mature leaves, demonstrating that PSII in newly initiating leaves is more sensitive to heat stress. Further analysis revealed that PSII structure in newly initiating leaves showed a robust alteration under heat stress, which was reflected by the clear K phase in the OJIP curves. Therefore, we suggest that the enhanced thermostability of PSII in the case of leaf growth might be associated with an improvement of the stability of the oxygen-evolving complex (OEC) to heat stress during leaf development. [Copyright &y& Elsevier]