Characteristics of diurnal variation about photosynthetic physiology of spring wheat in dryland at high altitude locality
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DOI:10.7606/j.issn.1000-7601.2011.04.07
Key Words: wheat in dryland  sowing on different dates  diurnal variation of photosynthetic characteristics
Author NameAffiliation
MA Xingxiang Key Laboratory of Arid Climate Change and Reducing Disaster, Lanzhou Institute of Arid Meteorology, China Meteorological Administration, Lanzhou, Gansu 730020, China
Wuwei Agro-meteorological Experiment Station, Wuwei, Gansu 733000, China 
WANG Runyuan Key Laboratory of Arid Climate Change and Reducing Disaster, Lanzhou Institute of Arid Meteorology, China Meteorological Administration, Lanzhou, Gansu 730020, China 
YANG Yonglong Key Laboratory of Arid Climate Change and Reducing Disaster, Lanzhou Institute of Arid Meteorology, China Meteorological Administration, Lanzhou, Gansu 730020, China
Wuwei Agro-meteorological Experiment Station, Wuwei, Gansu 733000, China 
YAO Taofeng Key Laboratory of Arid Climate Change and Reducing Disaster, Lanzhou Institute of Arid Meteorology, China Meteorological Administration, Lanzhou, Gansu 730020, China 
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Abstract:
      An experiment was conducted to measure photosynthetic elements of flag leaves and compare the characteristics of diurnal variation about photosynthetic physiology on various sowing dates of wheat named Longchun 8 in Wushaoling. The results show that the net photosynthetic rate and water utilization have increasing trends after pushing their sowing dates. In process of diurnal variation, the transpiration rate is less, water utilization is higher, and photosynthetic rate is stronger in morning than in afternoon, which turns a phenomenon of photosynthetic siesta. On different sowing dates, air temperature has relationships with photosynthetic elements of spring wheat. In higher air temperature time, air temperature is negatively correlated with net photosynthetic rate and water utilization, but it has unfavorable impact if air temperature is too high. Temperature is positively correlated with transpiration rate, reflecting that the higher temperature is, the larger transpiration rate of leaves is, which has disadvantage of photosynthetic accumulation. Air humidity has positive impact on net photosynthetic rate, and the correlativity between air humidity and net photosynthetic rate has an i ncreasing trend with pushing sowing dates. Air humidity also has positive correlations with leaf stomata transmitting rates, intercellular CO2 concentration and CO2 concentration. High humidity would be advantageous to increase the intercellular CO2 concentration. The effective radiation is little negatively correlated with the photosynthetic elements, which shows that the area of Wushaoling has abundant sunlight supply, and the temperature and humidity are sensitive elements in the process of photosynthesis.