[In-situ Remediation Effect of Cadmium-polluted Agriculture Land Using Different Amendments Under Rice-wheat Rotation].

Exploring the effects of one-time amendment treatments on cadmium (Cd)-contaminated farmland soils is beneficial for providing a theoretical basis to effectively prevent Cd pollution in farmland soils and ensure the safe production of crops. Five amendments, including straw biochar, fly ash, sepiolite, white marble powder, and shale (particle size <0.2 mm, application rate 2.25 kg·m-2), were applied to the Cd-contaminated farmland soils. The soil nutrients, pH, soil available Cd, and Cd chemical forms in the soils and grain Cd concentration in the planted crops were determined to investigate the effects and persistence of one-time applications of the five amendments. The results showed that:① the application of the five amendments had little effect on soil nutrient content, but all of them could increase soil pH. Amendment treatments improved the transfer of Cd from the acid extraction fraction to residue fraction and further reduced the Cd availability in the soil. The decreasing amplitudes of straw biochar and white marble powder soil conditioner were 20.42%-22.53%, which was higher than those in the other treatments. ② The grain Cd concentrations in rice and wheat were significantly decreased under the amendment treatments with the decreasing amplitudes of 19.88%-48.77% and 5.06%-24.00%, respectively. The Cd concentrations in rice grains under the treatments of straw biochar, fly ash, and white marble powder soil conditioner were 0.195, 0.196, and 0.223 mg·kg-1, respectively, which were lower than those under the other treatments and were close to or approached the National Standard of Food Safety(GB 2762-2017)(0.2 mg·kg-1). ③ The immobilization effects on Cd in farmland soils were decreasing with time under one-time application of the amendments. The available Cd concentrations in the soil and Cd concentrations in crop grains were still lower than those in the control after three rounds of rice-wheat rotation. The straw biochar and white marble powder soil conditioner had a good and long-term effect on reducing Cd availability in soils and Cd concentrations in crop grain, making them ideal materials for safe production in Cd-contaminated soils.

Breast-conserving in centrally located breast cancer patients confirmed safe by SEER based study.

BACKGROUND: Due to the lack of high-level data, there is still controversy over the oncological safety of breast conservation in patients with centrally located breast cancer. This study aimed to assess the safety of breast-conserving surgery in patients with centrally located breast cancer based on the data from the Surveillance, Epidemiology, and End Results (SEER) database. METHODS: We collected data for all cases diagnosed with breast cancer who underwent breast-conserving surgery from 2012-2014 in the SEER database. The primary outcome of our study was disease-specific survival (DSS) and overall survival (OS). The PSM was used to eliminate the effects of non-random statistics. Chi-square test, Kaplan-Meier method and Cox proportional hazards regression model on univariate and multivariate analysis were used to analyze the data. RESULTS: Data from 79,214 patients who had undergone breast-conserving surgery were analyzed in this study, including those with breast cancer in the central region (n=3,128) and outside the central region (n=76,086). The DSS of central breast cancer patients and outside the central breast cancer patients was 58.1 months versus 58.0 months (P>0.05), respectively, while the OS of the 2 groups was 58.0 months versus 58.0 months (P>0.05), respectively. CONCLUSIONS: Breast cancer in the central region should not be contraindicated for breast conserving surgery and breast-conserving surgery can benefit a wider range of patients.

[Effects of Different Amendments on Cadmium Accumulation in Rice Safety in Cadmium-Contaminated Farmland Under Two Flooding Treatments].

Cadmium (Cd) accumulation in rice has become a serious public concern; thus, it is important to find an effective approach to reducing Cd accumulation in rice grains to ensure food safety. To investigate the effects of different amendments on Cd accumulation in rice in Cd-contaminated farmland under different flooding treatments, a field experiment with three amendments (jade powder, biochar, and fly ash) and two flooding treatments (intermittent flooding and flooding throughout the whole growth period) was conducted. The results showed that:① without amendment application, the soil pH significantly increased, whereas the soil available Cd concentration decreased by 3.81%-17.27% and 2.25%-6.74% with the treatments of flooding throughout the whole growth period and intermittent flooding, respectively. Additionally, the immobilizing efficiency of the treatment of flooding throughout the whole growth period was better than that of intermittent flooding; ② under different flooding treatments, amendment application improved soil pH, resulting in a decrease in the soil available Cd concentration along with an increase in the residual Cd concentration. Under the treatment of intermittent flooding, the soil pH increased by 0.19-2.20 units, and the soil available Cd concentration and Cd concentration in rice grains decreased by 4.72%-22.68% and 2.60%-75.75%, respectively, with the application of different amendments. Under the treatment of flooding throughout the whole growth period, the application of different amendments decreased the soil available Cd concentration and Cd concentration in rice grains by 5.06%-36.63% and 13.28%-77.01%, respectively. The immobilizing efficiency in both flooding treatments was jade powder > biochar > fly ash. ③ Under different flooding treatments, the application of amendments significantly reduced the soil available Cd concentration and Cd concentration in rice grains. Among the three amendments, jade powder showed the best capacity of immobilizing efficiency with the treatment of flooding throughout the whole growth period; the soil Cd reduction rates were 36.63% and 25.16%, and the Cd concentrations in rice grains were 0.058 and 0.170 mg·kg-1 in 2019 and 2020, respectively. The Cd concentrations in rice grains were within the limitation of the National Food Hygienic Standard of China. Therefore, combining flooding throughout the whole growth period with jade powder can be considered as an ideal strategy for ensuring rice safety in Cd-contaminated farmland.

lncRNA KLF3-AS1 Suppresses Cell Migration and Invasion in ESCC by Impairing miR-185-5p-Targeted KLF3 Inhibition.

Esophageal squamous cell carcinoma (ESCC) is a common cancer occurring in males and females worldwide. Accumulating evidence continues to highlight the crucial roles of long non-coding RNAs (lncRNAs) in the process of tumorigenesis. However, the regulatory mechanism of lncRNAs in ESCC remains unclear. The aim of this study is to elucidate the role of lncRNA Krüppel-like factor 3 antisense RNA 1 (KLF3-AS1) in ESCC by regulating miR-185-5p and KLF3. Initially, ESCC cell spheres with stem cell-like properties were prepared by suspension culture, and subsequently characterized by assessing colony formation ability and stem cell markers. LncRNA KLF3-AS1 was found to be poorly expressed in ESCC and could upregulate the expression of KLF3 by binding to miR-185-5p. lncRNA KLF3-AS1 upregulation was observed to inhibit miR-185-5p, thereby contributing to decreased expression of SOX2 and Oct4 (octamer-binding transcription factor 4). Furthermore, enhancement of lncRNA KLF3-AS1 resulted in reduced colony formation ability, cell invasion and migration, and tumor volume in vivo while promoting cell apoptosis in ESCC through downregulation of miR-185-5p. Collectively, this study indicated that lncRNA KLF3-AS1 inhibited ESCC cell invasion and migration by impairing miR-185-5p-mediated inhibition of KLF3, highlighting a promising novel potential target for ESCC treatment.

[Characterization of cadmium uptake kinetics in cadmium pollution-safe rice material.] / æ°´ç¨»é•‰å®‰å ¨ææ–™çš„é•‰å¸æ”¶åŠ¨åŠ›å­¦ç‰¹å¾.

The characteristics of cadmium (Cd) uptake kinetics in a pollution-safe rice variety of D62B were studied in a hydroponic experiment under different Cd levels and stress time, with a common variety Luhui17 as the control. The results showed that Cd uptake in root of D62B was significantly lower than that of Luhui17 under different stress times. The differences in Cd uptake of the two rice varieties increased with the extension of absorption time. Total Cd amount of Luhui17 was 1.3 times as much as that of D62B when the absorption time was 72 h. Meanwhile, the Cd uptake kinetic of the two varieties accorded to Michaelis-Menten equation, and little difference in Michaelis constants (Km) was observed in the two varieties. However, the maximum uptake rate (Vmax) of Luhui17 was 2 times as much as that of D62B. Once the stress time was more than 48 h, the transfer coefficients of D62B was lower than that of Luhui17, and the Cd distribution ratio in root of D62B was much higher, indicating that D62B had greater accumulation ability in root compared with Luhui17. In conclusion, the Cd uptake and transfer ability of D62B were lower than those of Luhui17.

[Characteristics of soil aggregates and inorganic phosphorus fractions in soils returned from cropland to tea]. / é€€è€•æ¤èŒ¶åœ°åœŸå£¤å›¢èšä½“åŠå ¶æ— æœºç£·ç»„åˆ†åˆ†å¸ƒç‰¹å¾.

With soils returned from cropland to tea planting for different ages (2-3, 9-10 and 16-17 years old) as the object, and the nearby cropland soil as the control in Zhongfeng Township, Mingshan County, Ya'an, Sichuan Province, field investigation and laboratory analysis were combined to investigate the characteristics of soil aggregates and inorganic phosphorus fractions in response to the returning from cropland to tea. The particle size of >2 mm was the dominant aggregate size for the cropland and tea soils. With the increasing age, soil aggregate content of >5 mm particle size increased, while that of <5 mm particle size decreased gradually. In the earlier ages, for the mean mass diameter (MWD) and the geometry mass diameter (GWD), there was no significant difference between the cropland and tea soils. The MWD and GMD for the tea soils of 9-10 years and 16-17 years increased with the increasing age and were higher than those of the control. Compared with the cropland, the tea soils showed higher contents of Al-P and Fe-P, and lower content of O-P. The content of O-P in different particle size of aggregates reduced with the increasing age, while that of Al-P and Fe-P increased with the increasing age. The contents of Al-P and Ca-P in the cropland and tea soils increased with the decrease of the particle size and reached the maximum value in the particle size of <0.25 mm. The highest content of Fe-P was observed in the particle size of <0.25 mm, followed by 2-5 mm and 0.25-0.5 mm. Besides, with the returning fromcropland to tea planting, O-P gradually accumulated in smaller particle size and possessed higher content in the particle size of <2 mm.

[Topographical and pedological factors adapted to the growth of domestic truffles (Tuber indicum)].

Topographical and pedological factors at 9 sites of Tuber indicum in Yunnan, Sichuan and Tibet were studied by using principal component analysis in order to determine the connection between truffle-growth with topographic factors and soil factors. Results showed that: 1) The 5 principal components selected from 15 topographical and pedological factors had a great cumulative contribution, up to 87.5%. Among the topographical factors, the slope position was the most important ecological factor affecting truffles growth. The higher the slope position was, the less conducive to truffles growth. In the middle and lower parts of the slope, T. indicum grew best. 2) As for the pedological factors, the bulk density, silt content, pH, total nitrogen content, exchangeable calcium and magnesium contents were the important factors restricting T. indicum growth. Under the condition of bulk density 0.65-0.82 g · cm(-3), silt content 30.0% and sand content about 55.0%, T. indicum grew well. Too high bulk density or clay content was not conducive to its growth. The soil with pH 6.40 or so, total nitrogen content of 2.29-3.70 g · kg(-1), exchangeable calcium content of 22.91-37.17 cmol · kg(-1) and exchangeable magnesium content of 1.85-2.59 cmol · kg(-1) were favorable for growth of T. indicum. 3) The comprehensive evaluation showed that the site at Shaoshang Village in Kunming, Yunnan and Jiangsegang Village in Linzhi Prefecture, Tibet had higher scores, which meant these two sites had the most favorable conditions for truffles growth. However, the site at Ershijiu-liangzi Village in Panzhihua, Sichuan and the Mt. Wuding in Chuxiong Prefecture, Yunnan had lower scores, which meant these two sites were not fit for truffles growth regarding the topographical and soil conditions.

[Ecological stoichiometry of soil carbon, nitrogen and phosphorus within soil aggregates in tea plantations with different ages].

This study selected 4 tea plantations with different ages (12-15, 20-22, 30-33 and >50 year-old) located in Ya' an, Sichuan Province, China to investigate the distribution patterns of soil organic carbon (SOC), total nitrogen (TN) and total phosphorus (TP) , and to examine the ecological stoichiometric characteristics of C, N and P within soil aggregates. The results showed that the coefficients of variation of SOC, TN and TP were 17.5%, 16.3% and 9.4%, respectively in the 0-20 cm soil layer and were 24.0%, 21.0% and 9.2%, respectively in the 20-40 cm soil layer. The spatial variation of TP was lower than that of SOC and TN but there were significant positive correlations among them. SOC and TN were distributed in the small-size aggregates and both of them had the greatest values in the >50 year-old tea plantation, however, the distribution of TP was relatively uniform among aggregates and ages. The coefficients of variation of C/N, C/P, and N/P were 9.4%, 14.0% and 14.9%, respectively in the 0-20 cm soil layer and were 7.4%, 24.9% and 21.8%, respectively in the 20-40 cm soil layer. Variation of C/N was lower than that of C/P and N/P. Averaged C/P and N/P values in the small-size aggregates were higher than in aggregates of other sizes, and the maximum values were in the >50 year-old plantation. C/N, C/P and N/P had good indication for soil organic carbon storage.

[Root morphological characteristics of barley genotype with high phosphorus efficiency under phosphorus stress].

A pot experiment was carried out to test the effects of phosphorus (P) supply levels (25, 50, and 75 mg P2O5 . kg-1) with two P genotype (efficient DH110+ and DH147, inefficient DH49) barleys on root morphology and the relationships between root morphology and P uptake. The results showed that barley biomass and P uptake were significantly reduced by low P stress. Efficient genotype barley biomass and P uptake were 1.24-1.70 and 1.18-1.83 times as much as those of inefficient genotype barley respectively. The total root length, total root surface area, average root diameter, adventitious root length and root surface area, lateral root length and root surface area of P efficient genotype barley were significantly reduced with decreasing the P supply level in soil. The total root length, total root surface area, specific root length, lateral root length and surface area of P efficient genotype barley were 1.46-2.06, 1.12-1.51, 1.35-1.72, 1.69-2.42; and 1.40-1.78 times as much as that of those of P inefficient genotype barley, respectively, while the average root diameter was 70.6% - 90.2% of P inefficient genotype barley. Principal component analysis showed that the average root diameter, specific root surface area and specific root length could be used to distinguish two P genotype barleys. Partial least squares regression analysis showed that the total root length, total root surface area made great contributions to P uptake of barley in soil. The contribution of the adventitious root length and surface area on P uptake of barley decreased significantly and the average root diameter, specific root length, lateral root length and root surface area increased with the decreasing P supply level in soil. P efficient genotype barley adapted to low P stress through maintaining the lateral root growth, increasing the specific root length and root fineness.

[Characteristics of dry matter production and nitrogen accumulation in barley genotypes with high nitrogen utilization efficiency].

A pot experiment was conducted under low (125 mg x kg-1) and normal (250 mg x kg(-1)) nitrogen treatments. The nitrogen uptake and utilization efficiency of 22 barley cultivars were investigated, and the characteristics of dry matter production and nitrogen accumulation in barley were analyzed. The results showed that nitrogen uptake and utilization efficiency were different for barley under two nitrogen levels. The maximal values of grain yield, nitrogen utilization efficiency for grain and nitrogen harvest index were 2.87, 2.91 and 2.47 times as those of the lowest under the low nitrogen treatment. Grain yield and nitrogen utilization efficiency for grain and nitrogen harvest index of barley genotype with high nitrogen utilization efficiency were significantly greater than low nitrogen utilization efficiency, and the parameters of high nitrogen utilization efficiency genotype were 82.1%, 61.5% and 50.5% higher than low nitrogen utilization efficiency genotype under the low nitrogen treatment. Dry matter mass and nitrogen utilization of high nitrogen utilization efficiency was significantly higher than those of low nitrogen utilization efficiency. A peak of dry matter mass of high nitrogen utilization efficiency occurred during jointing to heading stage, while that of nitrogen accumulation appeared before jointing. Under the low nitrogen treatment, dry matter mass of DH61 and DH121+ was 34.4% and 38.3%, and nitrogen accumulation was 54. 8% and 58.0% higher than DH80, respectively. Dry matter mass and nitrogen accumulation seriously affected yield before jointing stage, and the contribution rates were 47.9% and 54.7% respectively under the low nitrogen treatment. The effect of dry matter and nitrogen accumulation on nitrogen utilization efficiency for grain was the largest during heading to mature stages, followed by sowing to jointing stages, with the contribution rate being 29.5% and 48.7%, 29.0% and 15.8%, respectively. In conclusion, barley genotype with high nitrogen utilization efficiency had a strong ability of dry matter production and nitrogen accumulation. It could synergistically improve yield and nitrogen utilization efficiency by enhancing the ability of nitrogen uptake and dry matter formation before jointing stage in barley.

[Characteristics of distribution and transportation of rice genotype with high nitrogen utilization efficiency at the late growth stage].

Taking a high nitrogen utilization efficiency rice genotype (NUE(H)) as test material and a low nitrogen utilization efficiency genotype (NUE(L)) as control, a pot experiment was carried out with nitrogen treatments of 100 (low) and 200 mg x kg(-1) (normal), to analyze the differences in nitrogen accumulation distribution, translocation and transport efficiency between the two genotypes. The results showed that NUE(H) could still maintain a high yield and a high nitrogen utilization efficiency at the low rate of nitrogen fertilization, with the grain yield being 1.75 times of that of NUE(L), and the nitrogen recovery efficiency of 50.9% compared with 36.4% for NUE(L). Compared to the normal nitrogen fertilization rate, the low nitrogen fertilization rate promoted the nitrogen accumulation by 34.2%, 2.5% and 0.5% in NUE(H) at the flowering, filling and mature stages, while decreased by 23.5% and 15.6% in NUE(L) at filling and mature stages, respectively. Nitrogen accumulation distribution in organs of NUE(H) was in the order of leaf > stem > root > spike, spike > leaf > stem > root, and spike > stem > leaf > root at the flowering, filling and mature stages, respectively. With the advancement of growth period, the nitrogen accumulation in spike increased obviously. At the two nitrogen fertilization rates, nitrogen transfer was ordered as leaf > stem > root for NUE(H), and stem > leaf > root for NUE(L), and nitrogen transfer efficiencies of NUE(H) were 50.8%, 60.3%, which were as 1.67 and 1.55 times as that of NUE(L), respectively. It could be concluded that the higher nitrogen transport efficiency of NUE(H) leaves laid a good foundation for the construction of grain after heading.

[Effect of silicon on translocation and morphology distribution of lead in soil-tobacco system].

Taking tobacco as test material, a pot experiment was conducted to study the effect of silicon on translocation of lead (Pb) form soil to tobacco in order to explore effective measures for reducing Pb concentration in tobacco leaf. The results showed that silicon application promoted the transformation of exchangeable Pb into Fe-Mn oxide-bound Pb in non-rhizospheric soil, and into Fe-Mn oxide-bound Pb and residual Pb in rhizospheric soil, which decreased the availability and mobility of Pb in the soil. Silicon application significantly reduced the Pb uptake of tobacco, with the content of Pb being decreased by 6.5% to 44.0% in tobacco, and 3.1% to 60.4% in leaf. Silicon application promoted the transformation of ethanol-extractable, H2O-extractable Pb and NaCl-extractable Pb into HCl-extractable Pb and residual Pb in root, stem and leaf of tobacco, which reduced the toxicity and mobility of Pb in tobacco. Silicon restricted the transportation of Pb from soil to tobacco leaf by reducing the mobility index of Pb from soil to root and the mobility index of Pb from root to stem in soil-tobacco system. Meanwhile, the mobility index of Pb from stem to leaf in soil-tobacco system showed a rising-and-falling trend with the increase of Pb application. Silicon inhibited the Pb migration from soil to tobacco leaf by reducing availability of Pb, mitigating toxicity of Pb to tobacco, and changing the distribution of Pb forms in tobacco, consequently reducing Pb concentration of tobacco leaf. These results demonstrated silicon application could be effective in reducing translocation of Pb from soil to tobacco.

[Effects of phosphorus sources on phosphorus fractions in rhizosphere soil of wild barley genotypes with high phosphorus utilization efficiency].

High P-efficiency (IS-22-30, IS-22-25) and low P-efficiency (IS-07-07) wild barley cultivars were chosen to evaluate characteristics of phosphorus uptake and utilization, and properties of phosphorus fractions in rhizosphere and non-rhizosphere in a pot experiment with 0 (CK) and 30 mg P · kg(-1) supplied as only Pi (KH2PO4), only Po (phytate) or Pi + Po (KH2PO4+ phytate). The results showed that dry matter and phosphorus accumulation of wild barley in the different treatments was ranked as Pi > Pi + Po > Po > CK. In addition, dry matter yield and phosphorus uptake of wild barley with high P-efficiency exhibited significantly greater than that with low P-efficiency. The concentration of soil available phosphorus was significantly different after application of different phosphorus sources, which was presented as Pi > Pi + Po > Po. The concentration of soil available phosphorus in high P-efficiency wild barley was significantly higher than that of low P-efficiency in the rhizosphere soil. There was a deficit in rhizosphere available phosphorus of high P-efficiency wild barley, especially in Pi and Pi+Po treatments. The inorganic phosphorus fractions increased with the increasing Pi treatment, and the concentrations of inorganic phosphorus fractions in soil were sorted as follows: Ca10-P > O-P > Fe-P > Al-P > Ca2-P > Ca8-P. The contents of Ca2-P and Ca8-P for high P-efficiency wild barley showed deficits in rhizosphere soil under each phosphorus source treatment. In addition, enrichment of Al-P and Fe-P was observed in Pi treatment in rhizosphere soil. The concentrations of organic phosphorus fractions in soil were sorted as follows: moderate labile organic phosphorus > moderate resistant, resistant organic phosphorus > labile organic phosphorus. The labile and moderate labile organic phosphorus enriched in rhizosphere soil and the greatest enrichment appeared in Pi treatment. Furthermore, the concentrations of moderate resistant organic phosphorus and resistant organic phosphorus decreased in rhizosphere soil. The concentrations of labile and moderate labile organic phosphorus in rhizosphere soil of high P-efficiency wild barley were significantly higher than that of low P-efficiency wild barley in each phosphorus source treatment. However, moderate resistant organic phosphorus and resistant organic phosphorus concentrations had no significant difference between the two genotypes. Wild barley with high P-efficiency demonstrated a greater ability of mobilization and uptake Ca2-P, Ca8-P, Al-P and labile organic phosphorus than that with low P-efficiency under Pi deficiency.

Reconstructing a flavodoxin oxidoreductase with early amino acids.

Primitive proteins are proposed to have utilized organic cofactors more frequently than transition metals in redox reactions. Thus, an experimental validation on whether a protein constituted solely by early amino acids and an organic cofactor can perform electron transfer activity is an urgent challenge. In this paper, by substituting "late amino acids (C, F, M, T, W, and Y)" with "early amino acids (A, L, and V)" in a flavodoxin, we constructed a flavodoxin mutant and evaluated its characteristic properties. The major results showed that: (1) The flavodoxin mutant has structural characteristics similar to wild-type protein; (2) Although the semiquinone and hydroquinone flavodoxin mutants possess lower stability than the corresponding form of wild-type flavodoxin, the redox potential of double electron reduction Em,7 (fld) reached -360 mV, indicating that the flavodoxin mutant constituted solely by early amino acids can exert effective electron transfer activity.

[Screening of wild barley genotypes with high phosphorus use efficiency and their rhizosphere soil inorganic phosphorus fractions].

A pot experiment was conducted to investigate the differences of 16 wild barley genotypes in phosphorus (P) uptake and use efficiency under the same P supply levels and the characteristics of inorganic P fractions in rhizosphere and non-rhizosphere soils of high P use efficiency genotypes. There existed greater differences in the P use efficiency for dry matter production at jointing stage (CV = 11.6%) and flowering stage (CV = 12.4%), and in the P use efficiency for grain yield at maturing stage (CV = 13.7%) among the genotypes. The biomass, P accumulation amount, and P use efficiency for dry matter production of high P use efficiency genotypes (IS-22-30 and IS-22-25) were significantly higher than those of low P use efficiency genotype (IS-07-07), and the grain yield of IS-22-30 and IS-22-25 was 3.10 and 3.20 times of that of IS-07-07, respectively. When supplied 0 and 30 mg x P kg(-1), the concentrations of available P and water soluble P in rhizosphere soils were significantly lower than those in non-rhizosphere soils, especially for the water soluble P. The concentrations of inorganic P fractions in the rhizosphere and non-rhizosphere soils were in the order of Ca10-P > O-P > Fe-P > Al-P > Ca2-P > Ca8-P. When supplied 30 mg x P kg(-1), the Ca8-P concentration in high P use efficiency genotypes rhizosphere soils at jointing and flowering stages was significantly lower than that in low P use efficiency genotype rhizosphere soil, but the Ca2-P concentration was in adverse. When no P was supplied, the concentrations of Ca2-P and Ca8-P in high P use efficiency genotypes rhizosphere soils were significantly higher than those in low P use efficiency genotype rhizosphere soil, and the Ca10-P concentration in the rhizosphere soils of all genotypes decreased. When supplied 30 mg x P kg(-1), the Fe-P and O-P concentrations in high P use efficiency genotypes rhizosphere soils were significantly higher than that in low P use efficiency genotype rhizosphere soil, but the Al-P concentration presented an opposite trend. Under no P supply, the Al-P, Fe-P, and O-P concentrations in high P use efficiency genotypes rhizosphere soils were significantly lower than those in low P use efficiency genotype rhizosphere soil. It was suggested that under low P stress, the capabilities of high P use efficiency genotypes in activating and absorbing soil A1-P and Ca2-P were stronger than those of low P use efficiency genotype.

[Differences in phosphorus utilization efficiency among wheat cultivars].

A pot experiment was conducted to study the differences in the biomass, phosphorus concentration, phosphorus use efficiency for dry matter, and phosphorus use efficiency for grain yield among different wheat cultivars under low phosphorus supply, aimed to screen the wheat varieties with high phosphorus use efficiency. For the test cultivars, their biomass per plant at tillering, jointing, flowering, and maturing stages was 0.46-1.09, 0.85-2.10, 3.00-7.00, and 3.85-12.88 g, and their phosphorus concentration was 2.21-4.26, 2.38-4.42, 2.44-4.96, and 1.30-5.09 mg x g(-1), respectively. From tillering to maturing stages, the phosphorus accumulation in plant and the phosphorus use efficiency for dry matter displayed a decreasing effect on the biomass formation. Significant differences were observed in the phosphorus use efficiency for dry matter (tillering stage CV = 16.3%, jointing stage CV = 15.0%, and flowering stage CV = 13.3%) and in the phosphorus use efficiency for grain yield (maturing stage CV = 20.5%) among the cultivars. The cultivars CD1158-7 and Sheng A3 Yi 034 had higher phosphorus use efficiency for dry matter and phosphorus use efficiency for grain yield, while the Yu 02321 was in adverse. The phosphorus concentration in the cultivars with high phosphorus use efficiency was significantly lower than that in the cultivars with low phosphorus use efficiency, and the grain yield of CD1158-7 and Sheng A3 Yi 03-4 was 0.98 times and 0.78 times higher than that of Yu 02321.

[Genotype difference in nitrogen utilization efficiency of wheat].

A pot experiment with 130 wheat cultivars was conducted to study their genotype difference in biomass per plant, nitrogen accumulation, and nitrogen production efficiency under the same level of nitrogen supply, aimed to screen the high efficiency nitrogen-utilizing wheat genotypes. The results showed that the biomass per plant of the cultivars at jointing, heading, and maturing stages was within the ranges of 1.06-3.08 g, 1.88-9.05 g, and 2.64-13.75 g, respectively, and the yield per plant was 1.38-9.90 g. The nitrogen dry matter production efficiency was 25.62-65.41 g x g(-1) N (F = 5.099 * *) at jointing stage and 35.79 - 88.70 g x g(-1) N (F = 5.325 * *) at heading stage, and the nitrogen production efficiency of grain yield was 19.06-38.54 g x g(-1) N (F = 4.669 * *) at maturing stage. There were significant differences in nitrogen dry matter production efficiency (jointing stage, F = 637.941 * *; heading stage, F = 201.173 * *) and nitrogen grain yield production efficiency (maturing stage, F = 443.450 * *), and also, in biomass accumulation among the cultivars, but no significant differences in tiller number and effective tiller number. The wheat genotypes with high nitrogen utilization efficiency had the characteristics of less ineffective tiller, high nitrogen utilization before heading stage, and high effective nitrogen absorption and reuse capability at heading and maturing stage. The grain yields of high nitrogen efficiency genotypes Sheng CXK027-4 and Liangmai 4 were 2.44 times and 1.86 times higher than those of low nitrogen use efficiency genotype 694, and the nitrogen accumulation in grain yields was 2.06 times and 1.81 times higher than that of low nitrogen use efficiency genotype 694, respectively.

[Spatial distribution pattern of soil nitrogen in croplands at county scale and related affecting factors].

By using geostatistics and GIS, this paper studied the spatial distribution of soil nitrogen in the croplands in Shuangliu County of Sichuan Province, China, and analyzed the related affecting factors. There was a moderate spatial correlation between the contents of total nitrogen (TN) and available nitrogen (AN) in the cropland soils, and the spatial correlation distance was 15480 m for TN and 26980 m for AN. The regions with higher soil TN content were mainly in the north of the County, i. e., Jiujiang and Xinxing towns, while those with lower soil TN content were mainly in the southeast of the County, i. e., Hejiang and Sanxing towns. The soil AN content decreased obviously from north to south. The TN and AN contents in the soils developed from grey alluvium were significantly higher than those developed from purplish rock saprolith and old alluvium. Paddy soil had significantly higher contents of TN and AN than yellow soil and purple soil. Terrain condition affected the soil TN and AN contents to different degree, and hilly region had the lowest contents of soil TN and AN. Paddy fields had significantly higher contents of soil TN and AN, compared with dryland and orchards; and the regions with higher soil nitrogen content were applied with obviously higher amount of N fertilizer, compared to the regions with lower soil nitrogen content.

[Research advances in plant lead tolerance and detoxification mechanism].

To have an overall understanding about the physiological mechanisms of plants in their lead (Pb) absorption, transportation, accumulation, and detoxification is the prerequisite of the phytoremediation of Pb-polluted soil. This paper reviewed the research advances in the mechanisms of plant Pb-adaptation and recovery, including the functions of cell wall and vacuole in Pb-inactivation and sequestration in plant cells, the effects of plant root exudates on Pb bioavailability, the roles of antioxidative enzymes dismutase (SOD), peroxidase (POD), catalase (CAT), glutathione reductase (GR), and ascorbate peroxidase (APX), and of antioxidants phytochelatins (PCs) and glutathione in Pb detoxification, and the expression and function of metallothionein and Pb-specific genes. The further researches on the plant's Pb-tolerance and detoxification mechanisms as well as the technologies for phytoremediation of Pb-contaminated environments were prospected.

[Effects of exogenous Ca2+ on the growth and Zn accumulation of two Sedum alfredii Hance ecotypes].

A hydroponic study was conducted to investigate the biomass, root morphology, and zinc (Zn), calcium (Ca) and sulfur (S) contents of two Sedum alfredii ecotypes under effects of different concentration calcium (Ca2+) addition. The results showed that with increasing exogenous Ca2+ concentration, the dry mass of the two S. alfredii ecotypes increased, and the shoot dry mass of hyperaccumulation ecotype increased significantly (P <0.05). The root length and root surface area of hyperaccumulation ecotype increased with increasing exogenous Ca2+ concentration, while those of non-hyperaccumulation ecotype were in adverse. The Zn accumulation in the root, stem and leaf of hyperaccumulation ecotype was increased with increasing exogenous Ca2+ concentration though the differences among Ca2+ treatments were not significant (P >0.05), while the Zn accumulation in the shoot of non-hyperaccumulation ecotype was significantly low (P <0.05). The Ca accumulation in the root, stem and leaf of non-hyperaccumulation ecotype had a significant positive correlation with the concentration of exogenous Ca2+ (P <0.05), so as the S accumulation in the root of hyperaccumulation ecotype (P <0.01). Exogenous Ca2+ promoted the Zn absorption and accumulation of hyperaccumulation ecotype, while inhibited the Zn accumulation of non-hyperaccumulation ecotype. Appropriate concentration of exogenous Ca2+ could promote the growth of hyperaccumulation ecotype S. alfredii, and improve its ability of accumulating more zinc.