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With rice (Oryza sativa L.) cultivar 3694 Fan as test material, and by using open top chambers, the effects of different ozone (O3) concentration on the leaf soluble protein content, lipid peroxidation, and antioxidant system were applied. Three treatments were applied, i.e., charcoal-filtered air (CF, 20 nl O3·L-1), non-filtered ambient air (NF, 40 nl O3·L-1), and elevated O3 (EO, 75 nl O3·L-1). The results showed that there were no significant differences in the test variables between treatments CF and NF. Compared with CF, EO induced a significant decrease of soluble protein content and significant increases of H2O2 and ASA contents and SOD, CAT and POD activities. In treatment EO, the SOD, CAT and POD activities increased by 93.7%, 39.9% and 312.4%, respectively, as compared with treatment CF, while the APX activity tended to increase at first and decrease then. MDA content had no significant differences among the treatments, indicating that leaf antioxidant system could significantly prevent the lipid peroxidation induced by elevated O3, and rice cultivar 3694 Fan could resist O3 to some extent. [ABSTRACT FROM AUTHOR]

The effects of canopy development, solar angle, and weather conditions on temporal variation in photosynthetic photon flux density(PPFD) at three heights within a tropical rain forest canopy in Xishuangbanna, China, were examined. PPFD was measured every second and stored as 10-min averages from 1 December 2002 to 30 November 2003. PPFD variability was examined at three different temporal scales. Specific days in March, September, and December with clear and overcast sky conditions were selected to separate the effects of leaf area index (LAI) and solar angle on diurnal variability. On both clear and overcast days, mean daily average PPFD was significantly different between March and September at all heights, except 10 m on clear days, suggesting that LAI directly influences PPFD. In contrast, the differences in daily average PPFD among three heights between September and December were likely due to variation in solar angle. In addition, daily average PPFD at all locations were significantly lower under overcast than clear sky conditions in March, September and December. Over the year-long study, the mean daily total PPFD at 21 m, 10 m and 4 m was 2.8, 2.7 and 0.7 mol/(m2 · d), which accounted for 9.7%, 9.4% and 2.4% of the daily PPFD above the canopy, respectively. Significant differences in mean daily total PPFD occurred at the same heights among different seasons, and diurnal, day-to-day and seasonal PPFD varied at different heights within the canopy. The possible effects of light variability on physiological and morphological responses of plants are discussed. [ABSTRACT FROM AUTHOR]

The effects of two lignins isolated from black liquor from pulping process on nitrification in soils after addition of urea, (NH[sub4])[sub2] SO[sub4] and (NH[sub4])[sub2] HPO[sub4] were investigated by incubation at 20 or 30°C for 7 or 14 d. The effects of lignin on nitrous oxide emissions from soil were also determined. Results showed that both lignins were more effective for inhibiting nitrification of NH[sub4] [sup+] -N as (NH[sub4])[sub2] SO[sub4] or (NH[sub 4])[sub 2] HPO[sub 4] as compared to urea-N. The effectiveness of lignin on nitrification was markedly affected by different soil type and temperature. Nitrous oxide emissions from soil declined when lignin was used. Urea plus 20 and 50 g/kg lignin reduced N[sub2]O emissions by about 83% and 96%, respectively, while (NH[sub4])[sub2]HPO[sub4] plus 20 and 50 g/kg lignin respectively reduced emissions by 83% and 93%. Because of its low cost and nonhazardous characteristics, lignin has potential value as a fertilizer amendment to improve N fertilizer efficiency. [ABSTRACT FROM AUTHOR]

Abstract: South China has become the third largest region associated with acid deposition following Europe and North America, the area subject to damage by acid deposition increased from 1.75 million km² in 1985 to 2.8 million km² in 1993. Acid deposition has caused serious damage to ecosystem. Combined pollution of acid rain and SO[sub 2] showed the obvious multiple effects on crops. Vegetable was more sensitive to acid deposition than foodstuff crops. Annual economic loss of crops due to acid deposition damage in eleven provinces of south China was 4.26 billion RMB Yuan. Acid deposition caused serious damage to forest. Annual economic loss of wood volume was about 1.8 billion RMB Yuan and forest ecological benefit loss 16.2 billion in eleven provinces of south China. Acid deposition in south China was typical "sulfuric acid type". According to the thoughts of sustainable development, some strategies were brought forward as follows: (1) enhancing environmental management, specifying acid-controlling region, controlling and abating the total emission amount of SO[sub 2]; (2) selecting practical energy technologies of clean coal, for example, cleansing and selecting coal, sulfur-fixed-type industrial briqutting, abating sulfur from waste gas and so on; (3) developing other energy sources to replace coal, including water electricity, atomic energy and the new energy such as solar energy, wind energy and so on; (4) in acid deposition region of south China, selecting acid-resistant type of crop and tree to decrease agricultural losses, planting more green fertilizer crops, using organic fertilizers and liming, in order to improve buffer capacities of soil. [ABSTRACT FROM AUTHOR]

Abstract: The impacts of different O[sub 3] concentration on the biomass and yield of rice were studied by using OTC-1 open-top chambers. Experimental treatments included the activated charcoal-filtered air (CFA), 50 nl/L (CF50), 100 nl/L (CF100) and 200 nl/L (CF200) concentrations of O[sub 3]. The O[sub 3] treatments significantly decreased the total biomass per plant. The elevated O[sub 3] exposure resulted in a more decrease in the root growth than in the shoot growth. Assessments of yield characteristics at the final harvest revealed an O[sub 3]-induced decrease in the number of grains per plant, resulting from fewer ears per plant, fewer grains per ear and more unfilled grains per ear. The 1000 grain dry weight and the harvest index (HI) were not changed significantly under 50 nl/L or 100 nl/L O[sub 3] exposure, but reduced by 17.0% and 4.8% by 200nl/L O[sub 3] treatment, respectively. Compared to the CFA treatment, CF50, CF100 and CF200 treatments caused a 8.2%, 26.1%, 49.1% decrease of the grain yield per plant, and a 14.2%, 31.7%, 51.7% decrease of the total biomass per plant, respectively. Linear regression showed that the 7h - daily mean O[sub 3] concentration exposure for 3 months (July-September) and AOT40 (cumulative exposure accumulation over threshold 40 nl/L) were well correlated with the relative grain yield. A yield loss of 10% was estimated to be at 46.9 nl/L O[sub 3] for 7h-daily mean O[sub 3] concentration exposure or at 12930 nl/(L x h) O[sub 3] for AOT40. [ABSTRACT FROM AUTHOR]

Presents information on a study which calculated the forest volume loss caused by acid deposition in seven provinces of south China. Background on the White Paper on Environment in China; Field investigations and methods; Results and discussion.

Effects of elevated 0[sub 3] on the yields of rice and winter wheat were studied by using open-top chambers(OTCs). Results showed that compared to the control treatment, 200 ppb, 100 ppb, 50 ppb treatments caused a 80.4%, 58.6% and 10.5% decrease in grain yields per winter wheat plant and a 49.1%, 26.1% and 8.2% decrease in grain yield per rice plant, respectively. According to the dose-response relation educed from OTCs experiment and the monitor data of O[sub3] concentrations in spots, it was estimated that the yield losses of rice and winter wheat resulted by O[sub3] pollution in the Yangtze River Delta region in 1999 were 0.599 million ton and 0.669 million ton, economic losses were 0.539 billion RMB Yuan and 0.936 billion RMB Yuan, respectively. [ABSTRACT FROM AUTHOR]

With rice (Oryza sativa L.) cultivar 3694 Fan as test material, and by using open top chambers, the effects of different ozone (O3) concentration on the leaf soluble protein content, lipid peroxidation, and antioxidant system were applied. Three treatments were applied, i.e., charcoal-filtered air (CF, 20 nl O3 x L(-1)), non-filtered ambient air (NF, 40 nl O3 x L(-1)), and elevated O3 (EO, 75 nl O3 x L(-1)). The results showed that there were no significant differences in the test variables between treatments CF and NF. Compared with CF, EO induced a significant decrease of soluble protein content and significant increases of H2O2 and ASA contents and SOD, CAT and POD activities. In treatment EO, the SOD, CAT and POD activities increased by 93.7%, 39.9% and 312.4%, respectively, as compared with treatment CF, while the APX activity tended to increase at first and decrease then. MDA content had no significant differences among the treatments, indicating that leaf antioxidant system could significantly prevent the lipid peroxidation induced by elevated O3, and rice cultivar 3694 Fan could resist O3 to some extent.

Assessing and predicting the impacts of ozone (O3) concentration on crop production have been drawing great attention in the scientific community. The ambient O3 concentration above the winter wheat field was observed with ML9810B O3 Analyzer in Jiaxing, Zhejiang Province. The impact of O3 on the wheat leaf photosynthesis was measured in open-top chamber. Based on the observed parameters, a numerical model for simulating the impact of O3 on the winter wheat development and yield was established, by added the effects of O3 on ear photosynthesis and leaf area. The results showed that the model properly simulated the impacts of O3 on wheat growth in field. The relative error of predicted biomass was 10.3%. The accumulated loss of photosynthate was 11.4% and yield loss was 17.8% at ambient O3 concentration in the wheat growth period under sufficient moisture and fertilizer supplies.

With 16 familiar species of understory shrub at Qianyezhou ecological experimental station in red soil hilly region under Chinese Academy of Sciences as test objects, crown area (A(c)) and projected volume (V(c)) were used as the variables for building quadratic and power allometric equations, respectively, to estimate the biomass of individual populations, and mixed-model was used to estimate the biomass of the 16 species. The best-fit models were applied to estimate the biomass of understory shrub in different forest types. The results showed that the biomass of shrub layer varied significantly among different stand types. With species-specific models, the biomass in deciduous, secondary, and coniferous forests was estimated as 4 773, 3 175 and 733 kg x hm(-2), respectively; while with mixed model, the estimation result was a little lower, being 3 946, 2 772 and 840 kg x hm(-2), respectively. Under the conditions of species-specific models being not established, mixed model was more convenient and practical in estimating the biomass of understory shrub.

In order to understand the possibility of AM in protecting crops from O3 pollution, simulated experiment was carried out to investigate effect of increased atmospheric O3 (0.02 microL x L(-1), 0.1 microL x L(-1) and 0.2 microL x L(-1)) on AM and its function. The results indicate that mycorrhizal colonization was slightly affected by elevated atmospheric O3, but spore and hypahe growth were significantly impacted. Spore number at high O3 level increased I times than that at ambient O3; hypahe length of AM at low and high O3 level decreased 48.7% and 85.6% than that at ambient O3, respectively. Root biomass, nodule number, horsebean pod and grain weight (excluding the treatment-- S + M) significantly decreased with elevated atmospheric O3, but they markedly increased after inoculation with AM fungi. Compared with the uninoculated treatment, nodule number increased by 2-5 times and grain weight of horsebean increased by 3-6 times after inoculation with AM fungi. Relative function of AM was slightly impacted by elevated atmospheric O3. Although indigenous microbes competed with inoculated AM fungi, inoculation with AM fungi could decrease the stress of O3 on plant, which was positive significant to alleviate crop loss resulted from O3 pollution.

The NO3(-)-N dynamics of the soil, soil solution and groundwater were studied under spring wheat and radish multiple-crop system in Hetao Irrigation District over two years. A strong tendency of NO3(-)-N to move from upper layer to deeper layer could be observed and soil NO3(-)-N was increased at the layer of 100 approximately 150cm. NO3(-)-N concentration of soil solution at the depth of 70 and 120 cm was significantly higher than that at the depth of 30 cm, especially in the radish growth season. NO3(-)-N leaching amount was correlated with deep percolation at both different crop growth seasons and different years and it accounted for higher than 30% of total N input across two years. In the fertilizer plot, the concentration of NO3(-)-N in groundwater was far higher than that in the non-fertilizer plot, and 65.5% samples were over the safe standard of WHO (11.3mg/L) in the fertilizer plot. The topsoil NO3(-)-N content was markedly decreased during the two years multiple-crop system. However, NO3(-)-N leaching was inevitable in the near future due to a large amount of residual NO3(-)-N in the middle and deeper soil profiles.