Biomedical subjects

Jianguo Zhu

Publications and source records attributed to Jianguo Zhu.

At least 19 recordsLinked to original sources

PubMed2004

[Quantification of non-point sources phosphorus pollution in key protection area of Taihu Lake].

The distribution of various kinds of non-point sources phosphorus pollution in Xueyan Town, Wujin city, Taihu area was researched through field experiments and local investigation during rice growth season. The results showed that of all kinds of phosphorus pollution, about 56.2% (1313 kg P) was from farmland, 22.2% (518 kg P) was from town residents, 18.9% (442 kg P) was from village residents, and 2.7% (62 kg P) was from livestock. Besides the strict control of the phosphorus pollution from farmland, attention should also be paid on the control of domestic water pollution from towns and villages.

Fresh Water↗

PubMed2003

[Effect of free-air CO2 enrichment on biomass accumulation and distribution in rice].

Investigation on the effect of free-air CO2 enrichment (FACE) on biomass accumulation and distribution in different parts of rice plant treated with 200 mumol.mol-1 CO2 elevation under field condition showed that the dry matter accumulated from transplanting to 20th day after heading and the total biomass increased significantly, while the dry mater accumulated from 20th day after heading to maturity was significantly depressed under FACE treatment. The enhancement of both leaf area index (LAI) and net assimilation rate (NAR) under FACE treatment resulted in the increase of dry matter accumulated from transplanting to heading, while the dominant reason for the increase of dry matter accumulated during 20 days after heading was the slowed decline of LAI. The decline of dry matter accumulated from 20th day to maturity was mainly caused by the decrease of NAR. The percentage of dry matter distributed in stem and sheath increased under FACE treatment, while that in leaf decreased, and that in panicle showed no significant change. The content (%) and amount of soluble sugar and starch in stem and sheath at heading was significantly elevated under FACE. The grain yield of rice under FACE treatment could be significantly improved by raising biomass.

Air↗

PubMed2003

[Effects of free air CO2 enrichment on rice canopy energy balance].

The change of crop canopy energy balance will affect crop growth and development and its water use efficiency. In this study, the FACE system (setup at at Anzhen, Wuxi, Jiangsu Province in 2001) was used to investigate the effects of FACE on rice canopy energy balance. The rice canopy microclimate observations were carried out from August 26 to October 13, 2001 when the rice crops were at the heading to maturing stage. The results showed that the maximum difference of rice canopy sensible and latent heat fluxes between ambient and FACE occurred at the same time of minimum air humidity, i.e., at about 14:00. From flowering to maturing stage, the maximum difference of rice canopy sensible and latent heat flux between FACE and ambient varied between 12-55 J.m-2.s-1 and -15(-)-65 J.m-2.s-1, respectively. The daytime total canopy sensible and latent heat fluxes of FACE were higher and lower than those of ambient, respectively, throughout flowering to maturing stage. The differences of daytime total canopy sensible and latent heat fluxes between ambient and FACE increased with the increase of net radiation above canopy during the same development stage, but decreased with the progress of the development stage. From flowering to maturing stage, the average difference of daytime total canopy latent heat flux between ambient and FACE was about 6.7%. FACE increased and decreased the ratio of daytime total canopy sensible and latent heat flux to daytime total net radiation above canopy, respectively, the ratio differences between FACE and ambient were 5.5%.

Air↗

PubMed2002

[Leaf photosynthetic acclimation of Echinochloa crusgalli grown in rice field to free-air CO2 enrichment (FACE)].

A comparative study was made between the leaves of Echinochloa crusgalli grown at 580 (FACE) and 380 (control, ambient air) mumol CO2 mol-1 air by observation of net photosynthetic rates (Pn) and the contents of soluble protein and the key enzyme of photosynthetic carbon assimilation, Rubisco. When measured at the ambient air CO2 concentration (380 mumol.mol-1), Pn were significantly lower in leaves grown under FACE conditions than that in those leaves grown in the ambient air. This indicates that photosynthetic acclimation to high CO2 occurs in the leaves grown under FACE conditions. Also, the stomatal conductance (Gs) and intercellular CO2 concentration (Ci) were decreased significantly in the leaves grown under FACE. The content of total soluble protein was much lower in the leaves grown under FACE conditions than that the in the control, and the content of Rubisco was also decreased in the FACE leaves, but the difference was not significant. From these results it is deduced that the photosynthetic acclimation to high CO2 in Echinochloa crusgalli leaves grown under FACE conditions is mainly related to the partial closure of stomata and the decrease in soluble protein containing some enzymes.

Acclimatization↗

PubMed2002

[Response and acclimation of photosynthesis in rice leaves to free-air CO2 enrichment (FACE)].

The net photosynthetic rate (Pn), water use efficiency (WUE), and apparent quantum yield of carbon assimilation of rice leaves were boserved contrastively under ambient air (380 mumol.mol-1 CO2) and FACE (580 mumol.mol-1CO2). The results showed that the observed index under FACE were significantly higher than those under ambient air. Nevertheless, along with the time of high CO2 treatment prolonged, the enhancement effect of high CO2 on net photosynthetic rate declined gradually. At the same CO2 concentration, Pn and carboxylation efficiency (CE) in rice leaves under FACE were lower than those under ambient air. Although the stomatal conductances in FACE leaves was obviously lower than that in ambient leaves, their intercellular CO2 concentrations were not significantly different, which implied that the photosynthetic down-regulation in rice leaves grown under FACE was not caused by the decrease of stomatal conductance.

Acclimatization↗

PubMed2002

[Effects of free-air CO2 enrichment (FACE) on yield formation in rice (Oryza sativa)].

Effect of Free-Air CO2 enrichment (FACE, 200 mumol.mol-1 higher than CK) on rice yield and its components under field condition were studied with a Japonica variety 99-15. Results showed that FACE treatment had no obvious effect on plant height and number of leaves on main stem, but could quicken growth process of rice, shorten the whole growth duration. Increment of nitrogen application rate could weaken the effect of FACE on whole growth duration. The number of tillers and panicles, and fulfilled-grain percentage increased significantly under FACE treatment, whereas spikelets per panicle decreased. FACE treatment could significantly increase grain yield of rice, especially when higher rate of nitrogen fertilizer was applied. Increasing spikelets per panicle and spikelets per unit area under FACE treatment would result in marked increment of rice yield. Increasing nitrogen application rate was an important approach to increase spikelets per panicle and spikelets per unit area under FACE treatment.

Air↗

PubMed2002

[Effect of free-air CO2 enrichment (FACE) on spikelets differentiation and retrogression in rice (Oryza sativa)].

Effect of Free-Air CO2 Enrichment (FACE), 200 mumol.mol-1CO2 elevation under field condition, on the number of differentiated, retrograded, and survived primary and secondary branches and their spikelets in rice was investigated, and the percentage of retrograded branches and spikelets under FACE treatment were also calculated. Results showed that the number of differentiated primary and secondary branches, the number and percentage of retrograded primary branches per panicle were not significantly affected by FACE, but the number and percentage of retrograded secondary branches per panicle significantly increased under FACE treatment, which resulted in the significant decrease of survived secondary banches. FACE had no significant effect on the number of differentiated, retrograded and survived spikelets on the primary branches per panicle. The number of differentiated spikelets on secondary branches per panicle was not significantly affected by FACE, but FACE treatment significantly increased the number and percentage of retrograded spikelets on the secondary branches per panicle. Significant decrease of survived spikelets per panicle under FACE treatment was chiefly caused by marked increase of retrograded spikelets on the secondary branches of survived primary branches. FACE treatment significantly increased the surviving percentage of spikelets on the primary branches per panicle, while that on the secondary branches significantly decreased under FACE treatment.

Air↗

PubMed2002

[Effect of free-air CO2 enrichment (FACE) on nitrogen accumulation and utilization efficiency in rice (Oryza sativa)].

Effect of FACE, 200 mumol.mol-1 CO2 elevation under field condition in this study, on nitrogen accumulation and nitrogen use efficiency in rice was investigated. Results showed that nitrogen content (%) in rice plant sampled at different growth stages decreased significantly under FACE treatment, but FACE had no obvious effect on nitrogen accumulation in rice plant due to the significant enhancement in dry matter production. FACE treatment resulted in the significant increase in nitrogen use efficiency for biomass production (NUEp) which was measured at 28th day after transplanting, at heading and at maturity, respectively. Significant increase in nitrogen use efficiency for grain output (NUEg) and nitrogen harvest index (NHI) under FACE treatment was also observed in this study. Nitrogen content (%) and nitrogen accumulation in rice plant were increased under high N, but nitrogen use efficiency in rice plant were decreased.

Air↗

PubMed2002

[Responses of rice (Oryza sativa) growth and its C, N and P composition to FACE (free-air carbon dioxide enrichment) and N, P fertilization].

FACE (Free-air Carbon Dioxide Enrichment) was used to study the effects of elevated CO2 on rice (Oryza sativa) growth, tissue C/N, N and P concentration and uptake at different development stages under two N and two P levels. Results showed that elevated CO2 increased dry matter accumulation in rice stem, ear and root. Leaf dry matter was increased at tillering stage and no significant effect was found at jointing, heading and ripening stages. N concentration of stem and leaf was decreased. Ear N concentration at heading stage was increased but was decreased at ripening stage. No significant effect was found on root N concentration at tillering stage but root N concentration at jointing, heading and ripening was decreased. Leaf P concentration at jointing, heading and ripening was increased but no significant effect was found on P concentration in stem, ear and root. C content in various tissues changed unremarkably and the ratio of C over N (C/N) was increased. Elevated CO2 significantly increased P uptake in aboveground tissues; and increased N uptake, but the difference was not statistically significant. N and P fertilization had no significant effect on various tissue dry biomass. Tissue N content at higher N fertilization was higher than at lower N fertilization but no such effect of P fertilization on tissue P content was found. At higher N fertilization, elevated CO2 increased the ratio of below-ground biomass over above-ground biomass at ripening stage. Possible reasons are discussed for the differences of tissue N and P content and the ratio of below-ground biomass over above-ground biomass between elevated and ambient atmospheric CO2 concentrations.

Air↗

PubMed2002

[Effect of FACE on competition between a C3 crop (rice, Oryza sativa) and a C4 weed (barnyardgrass, Echinochloa crusgalli)].

The growth and competition of a C3 crop rice and a C4 weed, barnyardgrass under FACE(free-air carbon dioxide enrichment) conditions were studied by field experiment. The results showed that under FACE condition, the biomass and yield, leaf number, tiller number, and leaf area index of rice increased, while those of barnyardgrass decreased. Both of the leaf area indexed of rice and barnyardgrass were decreased, while their net assimilation rate increased. When the ratio of planting density of rice and barnyardgrass was 1:1, all of the ratio of biomass, yield, leaf area index, tiller and net assimilation rate were increased under FACE condition. It indicated that the competition between rice and barnyardgrass changed under FACE condition. The competition ability of rice(C3 crop) was enhanced relatively, while that of barnyardgrass weakened.

Carbon Dioxide↗

PubMed2002

[Effects of free-air CO2 enrichment on rice canopy microlimate].

In this study, the free-air CO2 enrichment (FACE) system (setup at at Anzhen, Wuxi, Jiangsu Province in 2001) was used to investigate the effects of FACE on rice canopy microclimate. The rice canopy microclimate observations were carried out from August 26 to October 13, 2001, when the rice crops were at the heading to maturing development stage. The results showed that FACE reduced the rice leaf stomatal conductance. The rice leaf stomatal conductance difference between FACE and ambient was larger among upper layer leaves than among lower layer leaves and at heading and milk filling stages than at maturing stage. FACE increased daytime rice canopy temperature but had little effect on nighttime rice canopy temperature. The daytime rice canopy temperature difference between FACE and ambient was larger at heading and milk filling stages than at maturing stage. From heading to flowering, the daily maximum rice canopy temperature difference between FACE and ambient reached 1.2 degrees C under fine weather condition. The average daytime rice canopy temperature from flowering to maturing stage was about 0.43 degree C. Daytime air temperature inside rice canopy was also affected by FACE. Daytime air temperature inside rice canopy was higher in FACE plot than in ambient plot. The value of daytime air temperature difference between FACE and ambient increased with the increase of solar radiation and varied with height. The maximum daytime air temperature difference between FACE and ambient varied between 0.47-1.2 degrees C and 0.37-0.8 degree C at middle of canopy and canopy height, respectively. Air humidity and nighttime air temperature inside rice canopy were not significantly affected by FACE. These results indicate that FACE reducing rice leaf stomatal conductance was the major cause of the increase of canopy temperature and inside canopy air temperature in FACE plot. The higher canopy temperature and inside canopy air temperature in FACE plot resulted in the earlier maturity of rice crop in FACE plot than that in the ambient plot.

Air↗

PubMed2002

[Determination of net exchange of CO2 between paddy fields and atmosphere with static poaque-chamber-based measurements].

We firstly introduced the method for determining the net ecosystem exchange fluxes of CO2 (NEE) between croplands and atmosphere, based on field measurements using static opaquechamber/gas chromatography methods was introduced, and the application of this method in the FACE (free-air CO2 enrichment) study to examine the effects of elevated CO2 on the NEE over a typical paddy ecosystem was carried out, because of lacking in observation data for some necessary parameters, e.g., dark maintenance respiration coefficient, only the minimum value of NEE (NEEmin) was calculated based on opaque-chamber measurements. The NEEmin data indicate that CO2 elevated by 200 +/- 40 mumol.mol-1 significantly increased the ecosystem uptake of atmospheric CO2 by a factor ca. 3. To accurately determine the NEE based on opaquechamber measurements, dark maintenance respiration coefficient, above-ground biomass and root: shoot, i.e. R:S, ratio of root to shoot should be observed over the whole growing season.

Air↗

PubMed2002

[Effects of elevated atmospheric CO2 on CH4 and N2O emissions from paddy fields].

Effects of elevated atmospheric CO2 on CH4 and N2O emissions during the paddy rice-growing season were examined in a FACE (free-air carbon dioxide enrichment) study. The emission fluxes of CH4 and N2O from paddy rice fields were measured using methods based on static opaque-chamber and gas chromatography techniques. Synthetic fertilizer N was amended for the rice-growing season at two rates, 150 and 250 kgN.hm-2 and the atmospheric CO2 was enriched by 200 mumol.mol-1. At both N levels, the preliminary results indicate that no significant effect of CO2 enrichment on CH4 and N2O emissions from the rice paddy fields was detected. The result on CH4 emissions is inconsistent with the most literatures, and the result on N2O emissions is consistent with the most literatures.

Air↗

PubMed2002

[Measurement of CO2 profiles in non-waterlogged soil in a FACE study].

A method was specially designed and applied for measuring CO2 concentration of soil air over the non-waterlogged period of a rice-wheat rotation on an available area of about 1.6 m2 in a FACE (free-air CO2 enrichment) study. Based on measuring the CO2 concentration over the soil profile of 0-30 cm in depth using this method, the CO2 profile in the soils of wheat fields under elevated and ambient CO2 and the bare land under ambient CO2 was investigated and some preliminary results were obtained. Within 0-30 cm in soil depth, CO2 in the pores of the upper soil layers vertically diffused upwards much more quickly than that in the lower soil layers. During the period with active wheat growth, elevated atmospheric CO2 by 200 +/- 40 mumol.mol-1 significantly increased the CO2 concentration in soil air within 0-30 cm in depth by 14% +/- 5% (t-test, P < 0.001).

Air↗

PubMed2002

[Rice-wheat rotational FACE platform. I. System structure and control].

A Free Air CO2 Enrichment (FACE) system for rice and winter wheat rotation was established, elevated CO2 concentration was controlled to 200 mumol.mol-1 above ambient by computer system platform according to ambient CO2 concentration variation, wind direction, wind speed, canopy height and day-night changing. Experiments showed that the main factors affecting control precision are wind speed, crop and soil respiration and thickness of diffuse layer. After parameters adjustment, in daytime the time fraction for control precision achieve 80% is 83%, in night is 68%. The CO2 concentrations distribution in FACE rings are uniformity. The set CO2 is 557 mol.mol-1 in daytime and 608 mol.mol-1 in night. In 2001 rice season the target achievement ratios (TAR) were 1.03 after sunrise and 1.09 after sunset, respectively.

Agriculture↗

PubMed2002

[Rice-wheat rotational FACE platform. II. Data processing software package].

A large amount data are brought from daily control, data collection and processing of FACE platform. A FACE system control, data collection and processing software package written in Visual BASIC including OLE to support office functions can finish the platform control, data collection, original data save and backup, daily data processing, monthly data processing and whole time FACE system control status analysis functions, so FACE system controllers can observe FACE system control status and keep control precision timely, and the researchers can get the data they want at any moment and convenient.

Air↗

PubMed2002

[Field measurement of NO and NO2 exchanges between cultivated lands and the atmosphere in a FACE study].

A method for measuring NO and NO2 exchanges between cultivated lands and the atmosphere in a FACE (free-air CO2 enrichment) study is described. With this method, gas is sampled with a technique of static-opaque-chamber and the fluxes of NO and NO2 exchanges are determined by analyzing the NO and NO2 concentrations with a chemiluminescent NOx analyzer. Application of this method in the FACE study of a rice-wheat ecosystem has indicated that reliable data on the exchange fluxes could be obtained. Over the non-waterlogged period of a rice-wheat rotation, net emission of NO from the fields was observed, while net uptake of NO2 occurred. The daily net emission of NO did not correlated with the soil temperature, but negatively depended upon soil moisture (R2 = 0.82, P < 0.001). A significant seasonal variation in the net uptake of NO2 was observed, which was regulated by wheat growth status. The daily uptake of NO2 depended upon both soil temperature and soil moisture. The dependence for each could be described with a parabola function (for soil temperature: R2 = 0.74, P < 0.001; for soil moisture: R2 = 0.69, P < 0.001). An elevation of atmospheric CO2 by 200 +/- 40 mumol.mol-1 mitigated the net emission of NO by 19% (t-test P = 0.096) and might be possible to reduce the net uptake of NO2 by 10% (t-test P = 0.26), which was likely due to the stimulated wheat growth.

Air↗

PubMed2002

Effects of elevated atmospheric CO2 on nematode trophic groups in a Chinese paddy-field ecosystem.

Soil fauna plays significant roles in the detritus food webs of agroecosystems, they are the essential contributors to the decomposition of soil organic matter, mineralization of plant nutrients and nutrient cycling. Some evidences indicate that soil fauna of the detritus food webs appears to show positive, neutral or negative responses to global change, especially atmospheric CO2 enrichment across different studies. Soil nematodes are representative of a large portion of this fauna, since they are abundant and trophically diverse in most soils. The free-air CO2 enrichment (FACE) technology was used to expose three plots of rice (Oryza sativa) under elevated (ambient + 200 mumol.mol-1) atmospheric CO2, while three control plots were outfitted with FACE apparatus under ambient CO2. Nematode trophic groups were monitored in this study at depths of 0-5 cm and 5-10 cm during rice jointing and ripening stages in Wuxi site, China. Significant differences were found between depths and sampling dates in the total numbers of nematodes, bacterivores, plant parasites and omnivores-predators during the study period. The total numbers of nematodes and bacterivores at the 5-10 cm depth were higher in treatment plots than in control plots across all sampling dates. At 0-5 cm depth, the numbers of bacterivores were higher in treatment plots than in control plots, while those of omnivores-predators exhibited an inverse trend during the study period. Significant differences were also observed between treatment plots and control plots in the numbers of fungivores in our experiment.

Animals↗