Chinese Journal of Agrometeorology ›› 2016, Vol. 37 ›› Issue (02): 158-165.doi: 10.3969/j.issn.1000-6362.2016.02.005

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Evapotranspiration Characteristics and Crop Coefficient Estimation of Paddy Rice

GAO Lei, SHEN Shuang-he, SHAO Li-ying, CHU Rong-hao, TAN Shi-qi   

  1. Jiangsu Key Laboratory of Agricultural Meteology/Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters, Nanjing University of Information Science & Technology, Nanjing 210044, China
  • Received:2015-06-30 Online:2016-04-20 Published:2016-04-18

Abstract: Based on evapotranspiration data in a lysimeter of paddy rice, the data of biological and meteorological during the growth season in Nanjing in 2012, the reference evapotranspiration (ET0), actual evapotranspiration (ETc), and actual crop coefficient (Kc) of paddy rice were calculated, and the crop coefficient model was established. The results showed that the daily ET0 changed as a single peak curve, with the peak at tillering-jointing stage. While the daily ETc changed as a two-peak type, with the peak at tillering and heading stages respectively. Both ET0 and ETc obvious varied as seasonal. The actual crop coefficient (Kc) was consistent with the K corrected by FAO, but their values generally differed. The relationship between establishing model and its affected factors was well, with their R2 = 0.887. A model describing relationships between daily Kc and biological factor (LAI) as well as environmental factors (air temperature, net solar radiation) was established and its estimate agreed very well with the actual crop coefficient, and the model was capable of predicting ETc of paddy rice (R2 = 0.943) from a formula ETc=KcET0 by use of the Kc estimates. This model could help simplify computation of crop coefficient and define the effect of different factors and know well its dynamic characteristics.

Key words: Lysimeter, Paddy rice, Evapotranspiration, Crop coefficient model