Leaf structure and some physiologic characteristics of low temperature wheat germplasm
低温小麦种质叶片结构及某些生理特性

Through a long-term observation on wheat canopy temperature, it was found that in the nature, there existed low temperature wheat germplasm (LTWG) with constant low canopy temperature, and high temperature wheat germplasm (HTWG) with constant high canopy temperature. The study on the leaf structure and some physiologic characteristics of LTWG during its blooming and milk-filling stages showed that the canopy temperature of LTWG was 1 to approximately 4 degrees C lower than that of HTWG. The mesophyll cells of LTWG functional leaves were smaller, more compact in cell arrangement, and 1 to approximately 2 cell layers more than those of HTWG's. The average thickness of three LTWG functional leaves was 166,192 and 165 micro/m, being 26 microm thinner than that of HTWG, average vein interval of three functional leaves was 257,231 and 245 microm, being 31 microm smaller than that of HTWG, average transverse area of big veins of three functional leaves was 5 961,6 580 and 5 603 microm2, being averagely 837 microm2 more than that of HTWG, and average transverse area of small veins was 1624, 1521 and 1 472 microm2, being averagely 246 microm2 more than that of HTWG. The chlorophyll content of three LTWG functional leaves was 2.8749, 2.8162, and 2.4129 g x 100(-1) g FW, net photosynthetic rate was 10.864, 10.8003, and 10.1939 micromol x m(-2) x s(-1), and transpiration rate was 0.0076, 0.0074, 0.0067 mol x m(-2) x s(-1), respectively, which were all higher than those of HTWG. It was revealed that there were close relationships among canopy temperature, organ structure, and physiologic function.