According to the study based on two types of millet varieties,thetype of middle height with big head and the compact and dwarf type,it is showed that,it was a single peak curve for canopy respiration (CR) rates changes in summer-sowing millet during the growth period,CR rates raised along with the densitys increase,the CR peak appeared in flowering stage.The CR rates of compact and dwarf type obviously increased than that of the type of middle height with big head in late growth stages,which was an important cause for low yield.The diurnal changes of CR formed a curve affected by temperature.The distribution of CR rates in canopy was that of upper 3 leaves＞that of stem and sheath＞that of middle 3 leaves＞that of heads＞that of lower leaves.The ratios of CR to CP were similar for two varieties,which were about 47%.%中秆大穗型和矮秆紧凑型2种不同类型的夏谷群体呼吸速率在整个生育时期的变化呈单峰曲线，且随密度的增大而提高，抽穗开花期达最大值。紧凑型品种后期呼吸速率高于中秆大穗型品种，后期呼吸消耗大是低产的重要原因。群体呼吸日变化为一随温度而变化的单峰曲线。群体呼吸速率在冠层中的分布，依此是上3叶＞茎鞘＞中3叶＞穗＞下部叶。群体呼吸/光合的比值，两品种相近，在47%左右。
展开▼
