This study was to understand the physiological changes of four kinds of crop seeds including baby corn, cowpea, radish and rape- seed, under the treatment of ultra-drying. Large amounts of seeds as experimental materi...This study was to understand the physiological changes of four kinds of crop seeds including baby corn, cowpea, radish and rape- seed, under the treatment of ultra-drying. Large amounts of seeds as experimental materials （ 10 kg for each material） were respectively dried to the suitable water content consistent with the ultra-dried seed criterion via heating at 50 ~C; then the physiological indices of these ultra-dried seeds such as water content, seed germination, dehydrogenase activity and SOD activity were measured. The results showed that except cowpea seeds, whose ultra-drying treatment should be controlled between two and four days, other three kinds of seeds were tolerant to high tem- perature and low water content. The ultra-dried seeds assumed similar or even higher activities than CKs, but showed no damage symptom. Our result proves that ultra-drying treatment via heating at 50 ℃ is safe and efficient to experimental seeds.展开更多
Over the last three decades, the Tibetan Plateau has exhibited a significant increase in air temperature and a significant decrease in wind speed. How the surface heat source has changed is an important issue in monso...Over the last three decades, the Tibetan Plateau has exhibited a significant increase in air temperature and a significant decrease in wind speed. How the surface heat source has changed is an important issue in monsoon research. Based on routine meteorological data, this study investigates the differences between methods for estimating trends in surface sensible heat flux on the Tibetan Plateau for the period 1984-2006. One is a physical method based on micro-meteorological theory and experi- ments, and takes into account both atmospheric stability and thermal roughness length. The other approach includes conven- tional empirical methods that assume the heat transfer coefficient is a constant value or a simple function of wind speed. The latter method is used widely in climatologic studies. Results from the physical method show that annual mean sensible heat flux has weakened by 2% per decade, and flux seasonal mean has weakened by -2%--4% except in winter. The two commonly used empirical methods showed high uncertainties in heat flux trend estimates, although they produced similar climatologies. Annual mean heat flux has weakened by 7% per decade when a fixed transfer coefficient is used, whereas the trend is negligible when the transfer coefficient is assumed a function of wind speed. Conventional empirical methods may therefore misrepresent the trend in sensible heat flux.展开更多
文摘This study was to understand the physiological changes of four kinds of crop seeds including baby corn, cowpea, radish and rape- seed, under the treatment of ultra-drying. Large amounts of seeds as experimental materials （ 10 kg for each material） were respectively dried to the suitable water content consistent with the ultra-dried seed criterion via heating at 50 ~C; then the physiological indices of these ultra-dried seeds such as water content, seed germination, dehydrogenase activity and SOD activity were measured. The results showed that except cowpea seeds, whose ultra-drying treatment should be controlled between two and four days, other three kinds of seeds were tolerant to high tem- perature and low water content. The ultra-dried seeds assumed similar or even higher activities than CKs, but showed no damage symptom. Our result proves that ultra-drying treatment via heating at 50 ℃ is safe and efficient to experimental seeds.
基金supported by National Natural Science Foundation of China (Grant Nos. 40875009, 40810059006)Key Innovation Project of Chinese Academy of Sciences (Grant No. KZCX2-YW-Q11-01),"100-Talent" Program of Chinese Academy of Sciences
文摘Over the last three decades, the Tibetan Plateau has exhibited a significant increase in air temperature and a significant decrease in wind speed. How the surface heat source has changed is an important issue in monsoon research. Based on routine meteorological data, this study investigates the differences between methods for estimating trends in surface sensible heat flux on the Tibetan Plateau for the period 1984-2006. One is a physical method based on micro-meteorological theory and experi- ments, and takes into account both atmospheric stability and thermal roughness length. The other approach includes conven- tional empirical methods that assume the heat transfer coefficient is a constant value or a simple function of wind speed. The latter method is used widely in climatologic studies. Results from the physical method show that annual mean sensible heat flux has weakened by 2% per decade, and flux seasonal mean has weakened by -2%--4% except in winter. The two commonly used empirical methods showed high uncertainties in heat flux trend estimates, although they produced similar climatologies. Annual mean heat flux has weakened by 7% per decade when a fixed transfer coefficient is used, whereas the trend is negligible when the transfer coefficient is assumed a function of wind speed. Conventional empirical methods may therefore misrepresent the trend in sensible heat flux.
