通过对小麦群体温度的多年观测，发现自然界存在冷温群体，其冠层温度偏低，叶片功能期较长，源较充足，对灌浆甚为有利。尤其这类群体中的冷型小麦，冷域发达，蒸腾旺盛，净光合率较高，更是利于子位充实。这种类型小支的发现为优良株系、品系、品种的选择提供了重要的理论和实践依据。 Through years of observation on the temperature of wheat population, it was found that cold population exists in nature, its canopy temperature is low, the leaf functional period is longer, the source is more adequate, which is very beneficial to the grouting. Especially in this group of cold wheat, developed cold area, strong exuberance, higher net photosynthetic rate, but also conducive to full enrichment of children. The discovery of this type of small branch provides an important theoretical and practical basis for the selection of fine lines, lines and varieties.