[Influence of light and temperature factors on biomass accumulation of winter wheat in field].

To explore the influence of light and temperature factors on the biomass accumulation of winter wheat at its development stages and in different organs, this paper analyzed the variation patterns of the biomass accumulation and the influence of TEP (thermal effectiveness photosynthetically active radiation) on the accumulation at each development stage, based on the observation data from the Xifen Agrometeorological Experiment Station in Gansu Province, including winter wheat phenophase and yield factors in 1981-2008, biomass at three-leaf, over-wintering, jointing, heading, milky maturity, and maturity stages in 1995-2008, and meteorological data in 1995-2008. The biomass accumulation of winter wheat in its whole growth period presented "S" curve, with the maximum value at heading-milky maturity stage. Since 1981, the TEP at heading-milky maturity stage increased with a rate of 3. 314 MJ x m(-2) x a(-1), and the TEP at other stages varied as parable curves. The TEP at turning green-jointing and milky maturity-maturity stages had a higher value in the 1990s and a lower value in the 1980s and early 21st century, while that at jointing-heading stage had a lower value in the 1990s but a higher value in the 1980s and early 21st century. There was a significant correlation between the TEP at each development stage and the actual yield. The LAI (leaf area index) at each development stage also had a significant correlation with the utilization rate of TEP at corresponding stage. When the LAI at jointing and heading stages was increased by 1, the utilization rate of TEP was correspondingly increased by 0.049 and 0.259 g x MJ(-1), respectively.

[Responses of winter wheat growth to winter warming in Gansu Province].

Based on the observation data of the air temperature at Tianshui and Xifeng in 1951-2005 and of the phenology of winter wheat at Tianshui and Xifeng in 1981-2003, the tendency of winter warming in past 50 years and the responses of winter wheat growth to climate warming in Gansu Province were analyzed. The results showed that the growth and development of winter wheat were seriously influenced by winter warming. In recent 20 years or more, the overwintering mortality of winter wheat dropped to <2% , overwintering days reduced by 7-8 days, whole growth period shorted by 8-10 days, and jointing-flowering period extended by 7 days, which would benefit the production of winter wheat and the utilization of climatic resource. However, the higher winter temperature and lesser precipitation also made the grain yield instable and the plant diseases and insect pests more frequent, resulting in more uncertain factors in winter wheat safe production.