Study on the variation of sap flow rate and its influencing factors in summer maize growth season
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DOI:10.7606/j.issn.1000-7601.2020.02.26
Key Words: summer maize  sap flow rate  meteorological factor  crop coefficient
Author NameAffiliation
FENG Dongxue Beijing Key Laboratory of Urban Hydrological Cycle and Sponge City Technology, College of Water Sciences, Beijing Normal University, Beijing 100875, China 
LIU Haijun Beijing Key Laboratory of Urban Hydrological Cycle and Sponge City Technology, College of Water Sciences, Beijing Normal University, Beijing 100875, China 
GAO Zhuangzhuang Beijing Key Laboratory of Urban Hydrological Cycle and Sponge City Technology, College of Water Sciences, Beijing Normal University, Beijing 100875, China 
TANG Xiaopei Beijing Key Laboratory of Urban Hydrological Cycle and Sponge City Technology, College of Water Sciences, Beijing Normal University, Beijing 100875, China 
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Abstract:
      FLOW32-1K wrapped sap\|flowmeter was used to measure sap\|flow rate, and the correlation between transpiration of 2018 summer maize (zhengdan958) (sap\|flow was used in this study) and meteorological factors, including net radiation, temperature, saturation water pressure difference (VPD), and wind speed, were analyzed and evaluated with Pearson correlation coefficient. The results showed that the soil moisture content was maintained at 70%~80% of the field water retention rate during the experiment, and it was concluded that under the condition that maize was not subjected to water stress, the sap flow rate was linearly correlated with the net radiation, temperature, VPD and wind speed, and the correlation coefficients were 0.754, 0.622, 0.674 and 0.443, respectively, indicating that solar radiation had the closest relationship with the sap flow rate and the smallest relationship with wind speed.In the growth period from flowering to maturing stages, the daily sap flow curve on sunny days showed a single peak. It started at 5∶00 AM, then increased and reached the peak value of 74.5 g·h-1at 11∶00 AM, after that decreased and lastly droped to 0.0 at 21∶00. In rainy days, the curve had multiple peaks, and the sap flow rate fluctuated greatly (0~37.7 g·h-1), mainly due to the instability of climate condition. During the grain\|filling stage, the leaf area index was approximate 4.4, and the basic crop coefficient Kcb, the ratio of transpiration to reference evapotranspiration was 1.0, then gradually decreased to 0.55 at harvest.