Response to Low Temperature and Evaluation on Cold Tolerance of Sugarcane at Seedling Stage

This study aimed to screen out cold-tolerant sugarcane cultivars through acomprehensive cold tolerance evaluation. A total of 9 sugarcane cultivars with good agronomic traits, bred by the Yunnan Agricultural University, were selected. They were treated by low temperaturestress （3 ℃）, and the changes of their cold-tolerant physiological and biochemical indices were monitored. The cold tolerance of the sugarcane cultivars was evaluated comprehensively by polar ordination. The results showed that the low temperature stress increased the averagemembrane conductivi- ty, soluble sugar content, MDA content, proline content, soluble protein content, chlorophyll content and peroxidase （POD） activity in sugarcane leaves by 21.21%, 134.1%, 83.60%, 35.47%, 47.72%, 9.07% and 565.2%, respectively, but decreased the superoxide dismutase （SOD） activity in sugarcane leaves by 19.67%. Among the 9 sugarcane cultivars, Dianzhe 03-91 showed the strongest cold tolerance, while Dianzhe 02-39 showed the poorest cold tolerance; the cold tolerance of Dianzhe 08-5, Dianzhe 05-103 and Dianzhe 01-58 was stronger than that of Dianzhe 04- 14, Dianzhe 04-429, Dianzhe 05-522 and Dianzhe 02-227.

Analysis of a Turning Cold Wave in Northern Xinjiang in Winter

Based on analyzing the circulation development of 100 hPa, 500 hPa, lower streamline field and the change of physical vadables, the diagnostic analysis of a turning cold wave process in northern Xinjiang from Feb. 10 -13th 2009 was carried out. The results showed that abnormality of 100 hPa polar vortex taking on stable two waves, catastrophe of 500 hPa western Siberian trough, strong cold advection and water vapor transport from Middle Asia are chief reasons of the process.

Extreme spring cold spells in North China during 1961–2014 and the evolving processes

This study presents the major features of extreme spring cold spells(ESCS)in North China during 1961–2014 and the evolving processes.During an ESCS,northern Eurasia is controlled by large-scale positive SLP anomalies and an anomalous anticyclone that continuously transport northern cold air to North China,causing significant,persistent,lower-than-normal daily temperatures.In fact,these positive SLP and anticyclonic wind anomalies begin to appear over northwestern Europe about 10 days prior to the ESCS.The anticyclonic wind anomalies keep moving southeastward and expand to the west of Lake Baikal until two days before the ESCS.Then,the center of the anomalous low-level anticyclone moves over Lake Baikal,inducing northerly wind anomalies that transport cold air into North China.In the following days,as the positive SLP anomalies weaken,the anomalous anticyclone and related northerly winds appear to wane,and the ESCS gradually comes to an end.The results may prove meaningful for the prediction and early warning of ESCSs.

Screening and optimization of EPA-producing antarctic psychrophilic bacterium Shewanella sp. NJ136

Two hundred strains of bacteria from Antarctic sea ice were collected and screened for their ability of producing eieosapentaenoic acid （EPA, 20： 5ω3） by means of Gas Chromatography/Mass Spetmmetry （GC/MS）. Eight strains of bacteria containing EPA were investigated, among which the outstanding one was recorded as NJ136. This bacterium was identified as Shewanella by the biochemical characteristics and 16S rRNA sequence. Response surface methodology （RSM） was applied to optimize the medium ingredients. A 24 full factorial central composite design （FFCCD） was employed to determine the naximum EPA production at optimum levels of pH, NaC1, glucose and yeast extract. The predicted optimal combination of media constituents for maximum 14.02 mg/g （ about 1.7-fold increase） EPA production were determined as 30.15%e （m/v） NaC1, 9.98 g/L glucose, 4.42 g/L yeast extract and pH 6.08. The actual experimental results were in agreement with the prediction.

A Study of Soil-dynamics Based on a Simulated Drought in an Alpine Meadow on the Tibetan Plateau

Extreme weather events have played an important role in driving the ecosystem dynamics in high altitude areas, but the underlying mechanism remains unclear. To understand if and how the soil processes of an ecosystem react to extreme drought, we manipulated a once-in-a-century meteorological extreme drought in an alpine meadow on the Tibetan Plateau, which is also known as the ＂forerunner of global weather changes＂. The extremity was determined by statistical extreme weather events with respect to a historical reference period from April to September during 1962 - 2004, where the local historical precipitation data was calculated and intensified to loo-year recurrent drought event with Gumbel I distribution. The indicators we measured included soil microbial biomass C/N/P and soil enzymatic activities of phosphatase （AP） disbounding organic phosphate, cellobiohydrolase （CBH）, β- glucocidase （BG）, N-releasing enzyme N-acetyl- glucosaminidase （NAG） as well as soil respirations, during and after the treatments. It was found that the manipulated event induced a rapid shift in microbial biomass and activities, indicating a lower resistance of the underground process. However, the microbial and biochemical parameters saw rapid recovery after the event, which meant the soil processes enjoyed high resilience. The high responsiveness and lag-time effects of the soil indicators rendered new horizons for us to evaluate the interaction between the extremes and the ecosystem stability. Our study indicated that the once-in-a-century extreme drought induced very short term response in the soil biotic process, and the soil processes worked to buffer against such events under the observation period.