Analysis on Effects of Chilling Damages on Flowers and Plants at Beibei Area in Winter and Its Prevention Countermeasures

[Objective] The aim was to provide direction for the development of flowers and plants industry at Beibei area of Chongqing.[Method] Effects of temperature ranges and influencing time of chilling damages in winter on local flowers and plants at Beibei area were analyzed,using extreme minimum temperature data during 1960 to 2009 and the phenological growth conditions and phenological observation data of Bougainvillea spectabilis Willd and Michelia champaca during 2005 to 2007 at Beibei area.[Result] Chilling damages affecting flowers and plants at Beibei area mostly emerged from late December to early February,the effects of which were relative serious in January with a temperature range from-2 to 5 ℃;the optimum temperatures were 12-28 ℃ for flowers and plants grown at Beibei area in Chongqing,being higher or lower than that temperature range will affect the normally overwintering flowering and growing;chilling damages affecting the flower seedlings would appear when being at extreme minimum temperatures lower than 6 ℃ for 3 d in any phenophase in winter.[Conclusion] According to the characters of chilling damages in winter,the influences of which on flowers and plants can be reduced through combining tendency prediction and adopting corresponding measures.

The Cause and Weather Circulation Features of Chilling Damage in Yuxi

[Objective] The aim was to study the reasons of low temperature and characteristics of weather in Yuxi City.[Method] The reasons of low temperature in Yuxi City were expounded.The types of low temperature and their influences on agricultural crops were introduced.The route of cold air and the typical circulation characteristics of low temperature were analyzed.[Result] The low temperature in Yuxi City was formed because of the influence of its topography and climate.The low temperature and cold disaster included frost,low temperature in spring and autumn;the influencing path of cold air in Yuxi City had four paths:northeast,north,northwest and east path.The circulation characteristics of snowing included southerly trough,strong and cold air,and cold front shear;under the long-term control of cold advection of upper air and cold high pressure in the low layer,the radiation,cooling and temperature reducing were the main circulation characteristics of heavy frost;the circulation background of low temperature in August was conductive to the strong cold air intruding the upper air circulation of Yuxi City.The cold trough in the north and low pressure in the south influenced the circulation in Yuxi City.[Conclusion] The study provided reference for the weather report and relevant professionals.

Research on Changes in Risk of Chilling Damage to Maize in Heilongjiang Province since 1980

Based on data of daily average temperature observed during maize growing period as well as data of different growing periods of maize at 24 meteorological stations in Heilongjiang Province from 1980 to 2010, changes in risk of chilling damage to maize since 1980 were analyzed. Initially, the risk of the hazard factor was calculated by adopting the criterion of ＂Comprehensive Decision System of Chilling Damage to Maize in Heilongjiang Province＂. Then, choosing the planting area of maize at 75 stations as the exposure degree index, risk zones of exposure degree were concluded. Afterwards, risk zones of maize sensitivity to chilling damage were outlined based on maize yield per unit area. At last, a comprehensive evaluation model of chilling damage to maize in Heilongjiang Province was established, and Heilongjiang Province was divided into 5 grades of risk zones according to the model. The results showed that compared with the period before 1995, the risk of chilling damage to maize was severer in the west area of Songnen Plain, and previous sub-low or medium risk of chilling damage to maize in the west of Sanjiang Plain changed into subhigh or hi qh risk since the middle 1980s.

Prediction of chilling damage risk in maize growth period based on probabilistic neural network approach

Low temperature chilling damage is one of the most serious disasters in maize production,which is a typical non-linear complex issue with numerous influencing factors and strong uncertainty.How to predict it is not only a hot theoretical research topic,but also an urgent practical problem to be solved.However,most of the current researches are focusing on post-disaster static descriptive assessment rather than pre-disaster dynamic predictive analysis,resulting in the problems such as no indicative result and low accuracy.In this study,the satisfaction rate of environmental accumulated temperature for maize production was used to measure the chilling damage risk,and a model for maize chilling damage risk prediction based on probabilistic neural network was constructed.The model was composed of input layer,pattern layer,summation layer and output layer.The obtained results showed that the prediction accuracy for the most serious risk level was as high as 0.91,and the rates of the Type I Error and Type II Error made by the model were 0.1 and 0.09,respectively.This indicated that the model employed was promising with good performance.The results of this research are of both theoretical significance for providing a new reference method of pre-disaster prediction to study maize chilling disaster risk and practical significance for reducing maize production risk and ensuring yield safety.