Correlations between the cold tolerance during the booting stage and the stomatal traits of flag leaf surface in rice.

The flag leaf stomatal traits of ten rice cultivars with different cold tolerance,which were examined by artificial climate chamber,were studied by using scanning-electron microscope.The results showed that the cold tolerant cultivar,such as 'Peiza ruangxiang','Tianyou 688',and 'Gangyou 825' had a low stomatal density,380~410 stoma per mm2,the cold susceptible cultivar 'Yueza 763' had a high stomatal density,618 stoma per mm2,and moderate cold tolerant cultivars had a moderate stomatal density,460~510 stoma per mm2.When the stomatal density was similar,the rice cultivar with big stoma had the low cold tolerance level.The cold tolerant cultivar,such as 'Peiza ruangxiang','Tianyou 688',and 'Gangyou 825' had a short total stomatal circumference,29.8~32.6 cm per unit leaf area,the cold susceptible cultivar 'Yueguangsimiao' had a long total stomatal circumference,46.9 cm per unit leaf area,and moderate cold tolerant cultivars had a moderate total stomatal circumference,35.1~39.3 cm per unit leaf area.When the total stomatal circumference per unit leaf area was similar,the rice cultivar with high stomatal density had the low cold tolerance level.The rice cultivar cold tolerance during the booting stage was significantly positively correlated with its flag leaf stomatal density and total stomatal circumference per unit leaf area.