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The objective of this study was to investigate the impact of sewage sludge amendment (SSA), with the rates of 0, 30, 75, 150, and 300 t ha−1, on soil chemical properties and biomass, aboveground and root growth, and nitrogen and phosphorus uptake of ryegrass (Lolium perenneL.) seedling grown on a mudflat soil. Results showed that SSA modified the chemical properties of mudflat soil by decreasing soil salinity and pH, increasing soil organic matter, total and available N and P, and heavy metals. The biomass of root and aboveground parts of ryegrass showed increments with increasing SSA rates. Maximum increases of 5.6- and 1.3-fold in fresh weight of aboveground parts and root of ryegrass were observed at 300 t ha−1rate. Root grown at all SSA rates showed positive response to higher nutrient availability in the mudflat soil with increasing root average diameter and volume. The root length and surface area at 30 t ha−1SSA rate was significantly higher than those in other treatments. The sewage sludge amendment increased N and P content in both aboveground and root parts of ryegrass. Cd, Cr, Cu, Mn, Ni, and Zn accumulation in ryegrass was positively correlated with SSA rates. However, heavy metal concentrations in ryegrass did not exceed the safety standard for feed in China (GB 13078-1999), except for Cd at 300 t ha−1SSA rate. The study suggests that sewage sludge can be applied for mudflat soil amendment, which provides an innovative solution pertaining to new arable land resources and solid waste disposal. The optimum SSA rate is 150 t ha−1with maximum plant yield yet permissible metal accumulation. [ABSTRACT FROM PUBLISHER]

A series of Ag–Pd/C catalysts with different Ag/Pd molar ratios were prepared by impregnation and characterized by N2 adsorption and XPS. The catalytic performance was investigated in the hydrodechlorination of carbon tetrachloride into chloroform. High selectivity toward chloroform, near 100%, was obtained over Ag–Pd/C bi-metal catalysts. A very pronounced surface enrichment with Ag in Ag–Pd/C catalysts determined by XPS may be responsible for the high selectivity of chloroform. It is suggested that hydrodechlorination of carbon tetrachloride into chloroform occurs on the surface of Ag in the Ag–Pd alloy and the role of Pd is to supply H atoms necessary. [ABSTRACT FROM AUTHOR]

To examine the possibility of breeding higher-yielding cultivars with a high nitrogen use efficiency (NUE) and to provide simple criteria for the selection and breeding of high-yielding cultivars with a high NUE and useful information for the mapping of quantitative trait loci (QTL) controlling NUE, recombinant inbred lines (RILs) of rice were subjected to hydroponic culture in 2000 and 2001. Grain yield and yield components, total nitrogen absorption (NTA), pre-heading and post-heading nitrogen absorption (pre-NA and post-NA, respectively), and nitrogen use efficiency for grain yield (NUEg) were analyzed. Transgressive segregations for grain yield and yield components, NTA and NUEg were observed. RILs with a high grain yield tended to show a larger number of panicles m−2 and of spikelets per panicle, and a higher filled grain percentage than RILs with a low grain yield. Increasing NTA and NUEg resulted in increases in the number of spikelets m−2 and grain yield, while increasing NTA resulted in a decrease in NUEg. The contribution ratio of the number of panicles m−2 to grain yield was higher than that of the other yield components in both 2000 (31.8%) and 2001 (32.2%). In both years, the relative contribution ratios of NUEg and NTA to grain yield were approximately 56% and 43%, respectively. At the same high-yielding level, there was a significant difference in the NTA and NUEg values. These results suggest the possibility of breeding high-yielding cultivars with higher NUEg. [ABSTRACT FROM AUTHOR]

Using free-air CO2 enrichment (FACE) platform and under different nitrogen supply level, this paper studied the phosphorus nutrition of Oryza sativa at its different growth stages. The CO2 concentration of FACE platform was 200 micromol.mol(-1) more than that in ambient air, and the nitrogen supply levels were 150 kg.hm(-2), 250 kg.hm(-2) and 280 kg.hm(-2). The results showed that during rice growth period, FACE significantly increased the phosphorus content of rice plant and its phosphorus uptake by 3.9%-20.6% and 28.9%-71.4%, respectively. Before heading, FACE had little effect on the phosphorous accumulation in leaf or stake, but after heading, made the proportion of phosphorus accumulation in reproductive organ decreased by 9.8%-26.3% and that in vegetative organ increased by 2.2%-23.9% at 0.01 or 0.05 significant level. Under FACE treatment, the phosphorus use efficiency for biomass production (PUEp) at different growth stages, the phosphorus use efficiency for grain output (PUEg), and the phosphorus harvest index (PHI) were decreased by 3.7%-16.6%, 6.5% -15.5%, 5.4%-9.0%, respectively. Nitrogen supply level and its interaction with FACE had less effect on the phosphorus-nutrition of rice at its different growth stages.

The study showed that under field condition, when the CO2 concentration was elevated 200 micromol x mol(-1) above control, the average brown rice rate of japonica variety Wuxiangjing 14 was 1.4% higher, while lead milled rice rate was 12.3% lower than control. The brown rice rate increased at lower nitrogen supply level (LN), while lead milled rice rate increased at higher nitrogen supply level (HN). The percentage of chalky grain was 11.9% higher, and chalkiness degree was 2.8% higher than control, but no obvious difference was found in chalkiness area between the FACE and the control. The chalkiness area, percentage of chalky grain and chalkiness degree decreased at HN plus higher phosphorus supply level (HP). The gelatinization temperature was elevated 0.52 degrees C, gel consistency increased, while amylose content was not statistically significant. The amylose content decreased at HN plus HP, while gel consistency and gelatinization temperature decreased at LN plus HP and at LN, respectively. The protein content was decreased 0.6% under FACE treatment and at LN plus lower phosphorus supply level.

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.

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.

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.

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.