Nutrient uptake requirements with increasing grain yield for rice in China

Improved estimates of nutrient requirements for rice（Oryza sativa L.）in China are essential to optimize fertilization regulation for increasing grain yields and reducing the potential of environmental negative influences,especially under high-yielding intensive systems.A database involving rice grain yields,nutrient concentrations and accumulations collected from on-field station experiments in the literatures published from 2000 to 2013 in China was developed to understand the relationships between grain yields and plant nutrient uptakes,and to quantify nutrient requirements for different yield levels.Considering all data sets,rice grain yield ranged from 1.4 to 15.2t ha^-1with the mean value of 7.84t ha^-1,and ca.10.4%of yield observations were higher than the yield barrier level of 10 t ha^-1.N requirement to produce one ton grain was 21.10 kg for the yield range<4.0t ha^-1with a high variation of 45.8%.Except of the yield range<4.0t ha^-1,the values of N requirement,firstly increased from 18.78 kg for yield range 4.0-5.5 t ha^-1to 20.62 kg for yield range 7.0-8.5 t ha^-1,then decreased slightly to 19.67 and19.17 kg for the yield range 8.5-10 and>10 t ha^-1,respectively.Phosphorus（P）and potassium（K）requirements showed increasing trends,from 3.51 and 19.87 kg per t grain for<4.0 t ha^-1yield range to 4.10 and 21.70 kg for>10.0t ha^-1range.In conclusion,nutrient requirement varied with increasement of grain yield,and N,P and K presented various response trends,increasing,declining or stagnating,which would be of great benefit for improving fertilizer strategies.     

普通玉米新品种试验初报

引进11个普通玉米进行试验,结果：登海661、郑单136、登海3622、济单7号比CK增产,登海661综合性状表现较好,可扩大示范种植。     

梨属野生种质资源SRAP-PCR反应体系优化研究

采用正交直观分析法和新复极差法对影响梨属野生种质资源SRAP-PCR反应的5种因素(Mg2+浓度、d NTPs浓度、引物浓度、Taq DNA聚合酶、模板DNA)4个水平进行优化筛选。结果表明,优化后的梨属SRAP-PCR反应体系为25μL,包括10×PCR buffer 2.5μL,2.0 mmol/L Mg2+,200μmol/L d NTPs,0.4μmol/L引物,1.5 U Taq酶,60 ng模板DNA。     

Characterizing long-term forest disturbance history and its drivers in the Ning-Zhen Mountains,Jiangsu Province of eastern China using yearly Landsat observations (1987–2011)

Forest losses or gains have long been recognized as critical processes modulating the carbon flux between the biosphere and the atmosphere. Timely, accurate and spatially explicit information on forest disturbance and recovery history is required for assessing the effectiveness of existing forest management. The major objectives of our research focused on testing the mapping efficacy of the vegetation change tracker (VCT) model over a forested area in China. We used a new version of VCT algorithm built upon the Landsat time series stacks (LTSS). The LTSS consisted of yearly image acquisitions to map forest disturbance history from 1987 to 2011 over the Ning-Zhen Mountains, Jiangsu Province of east China. The LTSS consisted of TM and ETM+ scenes with different projections due to distinct data sources (Beijing remote sensing ground station and the USGS EROS Center). The validation results of the disturbance year maps showed that most spatial agreement measures ranged from 70 to 86 %, comparable with the VCT accuracies reported for many places in USA. Very low accuracies were identified in 1995 (38.3 %) and 1992 (56.2 %) in the current analysis. These resulted from the insensitivity of the VCT algorithm to detect low intensity disturbances and also from the mis-registration errors of the image pairs. Major forest disturbance types existing in our study area were identified as agricultural expansion (39.8 %), urbanization (24.9 %), forest management practice (19.3 %), and mining (12.8 %). In general, there was a gradual decreasing trend in forest cover throughout this region, caused principally by China’s economic, demographic, environmental and political policies and decisions, as well as some weather events. While VCT has largely been used to assess long term changes and trends in the USA, it has great potential for assessing landscape level change elsewhere throughout the world.     

Effect of ammonia and nitrite on vigour,survival rate,moulting rate of the blue swimming crab <Emphasis Type="Italic">Portunus pelagicus</Emphasis> zoea

The effects of ammonia and nitrite on vigour, survival rate, moulting rate of zoea of blue swimming crab, Portunus pelagicus, were studied. A total of five nitrite-N treatments (26.67, 53.34, 106.68, 213.36, 426.72 mg/l) and a control (no nitrite-N added) were set up for the acute nitrite-N toxicity experiment; a total of five ammonia-N treatments (8.43, 16.86, 33.72, 67.44, 134.88 mg/l) and a control (no ammonia-N added) were set up for the acute ammonia-N toxicity experiment. The results showed that the vigour, survival rate and moulting rate of zoea of the blue swimming crabs exposed to over 53.34 mg/l were significantly different (P < 0.05) from the control group. The zoea LC₅₀ values (mg/l) of nitrite-N were 179.47, 76.56, 66.70, 37.49, 25.01, 25.35, 25.34 mg/l for 24, 36, 48, 60, 72, 84, 96 h, respectively. The vigour, survival rate and moulting rate of zoea of the blue swimming crabs exposed to over 16.86 mg/l were significantly different (P < 0.05) from the control group. The zoea LC₅₀ values (mg/l) of ammonia-N were 51.04, 39.62, 38.72, 24.43, 16.90, 13.42, 11.16 mg/l for 24, 36, 48, 60, 72, 84, 96 h, respectively. The zoeae are highly sensitive to ammonia and nitrite, and the toxicity of ammonia and nitrite on Portunus pelagicus decrease with development of this crab.     

分娩应激对围产期奶牛免疫机能的影响

本文分析了围产期奶牛的分娩应激对其免疫机能的影响,并从宏观和微观上进行了详细的阐述,为围产期奶牛的饲养管理提供了理论依据。