Analysis of the winter wheat yield components and causes under the extreme climatic conditions

This paper compares and analyses the climatic characteristics of extreme climatic year and the growth status of the over ground part of winter wheat. In the year of 2003, the climate is characterized as cold winter, chilly spring, scarce sunshine and abundant spring rainfall. Compared to 2002, the mainly developing stages of winter wheat have been postponed for 4～18 d, the unit area caudexes numbers(peak value)have been decreased by 29.1%, the biomass and leaf area index(LAI) falls to a great extent, unit head grains and one thousand-grain-weight increase by 6.31 and 3.21 g respectively, but the available caudexes number decreased to a great extend(320.84×10⁴/hm²), and resulted in reduction of output by 612.29 kg/hm². By analyzing the conclusion, the author believes that in the climatic anomalies year, improving the seed system, adjusting and controlling seeding rate by climate can control the unit head numbers indirectly and improve the winter wheat yield effectively.