Variation Characteristics of Low Temperature and Rainy Weather in Guangxi during Spring Sowing Period of Recent 50 Years

[Objective] The research aimed to study the variation characteristics of low temperature and rainy weather in Guangxi during spring sowing period of recent 50 years.[Method] Based on the daily average temperature data from 1961 to 2010 at 88 meteorological stations in Guangxi,yearly days and end date of low temperature and rainy weather during spring sowing period were carried out statistics.The variation characteristics of low temperature and rainy weather in Guangxi during spring sowing period of recent 50 years were analyzed by using linear tendency calculation,phased analysis,Morlet wavelet analysis and correlation analysis.Moreover,the influences of climate warming on days and end date of low temperature and rainy weather in spring sowing period were analyzed.[Result] The average days of low temperature and rainy weather in Guangxi during spring sowing period from 1961 to 2010 was during 3.5-23.2 d.The regional distribution characteristics were that it was more in northeast and mountain zone,and less in southwest and valley.The regional distribution characteristics of end date were that it was late in northeast and mountain zone,and early in southwest and valley.The days of low temperature and rainy weather in Guangxi during spring sowing period of recent 50 years presented slight decrease trend,and the end date presented slight advancing trend.The phased variation characteristics of days and end date of low temperature and rainy weather were obvious.The days of low temperature and rainy weather from the early 1980s to metaphase of 1990s was obviously more,and the end date was obviously later.After the 1990s,the days of low temperature and rainy weather was obviously less,and the end date was obviously earlier.The days of low temperature and rainy weather had periodic oscillation signals of 4,6,8,10-14 years.The end date had periodic oscillation signals of 6,12-14 years.The days and end date of low temperature and rainy weather in Guangxi during spring sowing period significantly related to average temperature from middle dekad of February to first dekad of April.The climate warming made that the days of low temperature and rainy weather tended to decrease,and the end date tended to advance.[Conclusion] The research provided reference for further understanding the occurrence rule of low temperature and rainy weather,going after profits and avoiding disadvantages,reasonably arranging production,carrying out correlated research.

Relationship between “Two Insects and One Spider” and Their Occurrence and Damage Regularity during Different Sowing Periods in Single Cropping Hybrid Rice

[Objective]The paper was to study the relationship between rice leaf roller,rice planthopper and spider and their ecological regulation ability in the field.[Method]The population dynamics of rice leaf roller,rice planthopper and spider at three different sowing and transplanting periods of single cropping hybrid rice in the treatment area with combination of 3 drug formulations and untreated area were monitored.[Result]There were significant or extremely significant positive correlations among rice leaf roller,rice planthopper and spider in single cropping hybrid rice.However,with the delay of planting and transplanting period,the population fluctuation crest of rice leaf roller and rice planthopper decreased,but the intensity increased with the advance of time,and the natural ecological regulation ability was relatively improved.[Conclusion]The sowing period of single cropping hybrid rice is delayed 5-10 d compared with conventional rice,that is,sowing in late May and early June.The seedling age of 20-30 d is beneficial not only to reduce the initial population quantity of rice leaf roller and rice planthopper in the field,but also to increase the population quantity of spiders.

Screening of Suitable Sowing Date for Yumi 2 in Arid Area of Western Heilongjiang Province

In order to determine the best sowing date of the main cultivar Yumi 2 of Shaanxi Province in western Heilongjiang Province,taking Yumi 2 as experimental materials,five sowing periods were set: May 8( B1),May 18( B2),May 28( B3),June 7( B4),and June 17( B5),and field experiment was carried out in Heping Pasture of Suihua Administration Bureau in Heilongjiang Province. The plant height,main panicle length,main stem node number,grain number per panicle,1000-grain weight,and yield of Yumi 2 were compared under different treatments. The results showed that the treatments of B1,B2 and B3 were higher than those of B4 and B5 in the plant height,main panicle length,main stem node number,grain number per panicle and 1000-grain weight. The yield of B1 was the highest in five treatments,and the yield was higher than that of B2,B3,B4 and B5 for 7. 41%,8. 33%,28. 70%,and 19. 44% respectively. Based on the above traits,it is concluded that the appropriate sowing date of Yumi 2 is May 8 in the arid area of western Heilongjiang Province so as to get higher yield.