Simulating the influences of soil water stress on leaf expansion and senescence of winter wheat

Authors: JIANG, TENGCONG - Northwest A&f University; DOU, ZIHE - Northwest A&f University; LIU, JIAN - Northwest A&f University; GAO, YUJING - University Of Florida; Malone, Robert - Rob; CHEN, SHANG - Northwest A&f University; FENG, HAO - Northwest A&f University; YU, QIANG - Northwest A&f University; XUE, GUINING - Northwest A&f University; HE, JIANQIANG - Northwest A&f University

Submitted to: Agricultural and Forest Meteorology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/26/2020
Publication Date: 6/10/2020
Citation: Jiang, T., Dou, Z., Liu, J., Gao, Y., Malone, R.W., Chen, S., Feng, H., Yu, Q., Xue, G., He, J. 2020. Simulating the influences of soil water stress on leaf expansion and senescence of winter wheat. Agricultural and Forest Meteorology. 291. https://doi.org/10.1016/j.agrformet.2020.108061.
DOI: https://doi.org/10.1016/j.agrformet.2020.108061

Interpretive Summary: Current crop models often provide poor simulations compared to field observations and need to be improved, especially when crops are stressed by low soil water availability. We developed and tested a new simulation model for leaf area expansion of water stressed winter wheat using soil column experiments and field studies under rainout shelters in Yangling, Shaanxi Province in China. The new model simulates crop water stress as a function of “relative effective soil water content”, which is calculated from soil water content and other easily determined soil variables. Current crop models such as the well-known CERES-wheat, simulate crop water stress as a function of potential water uptake and potential crop transpiration (water movement through a plant) and are more complex than using soil water content to estimate crop water stress. The new algorithm was reasonably accurate compared to field and soil column data and more accurate than the CERES-Wheat model, suggesting the results of this study provide a foundation for improving current models such as CERES-Wheat. This research provides a new (and perhaps easier and more accurate) method to simulate crop water stress. This research will help model developers, model users, and agricultural scientists more easily and accurately simulate crop production under water stress, which will help in designing more effective systems to conserve water and optimize crop production.

Technical Abstract: Current crop models often provide poor simulations compared to field observations when the soil water content is low and they need to be improved. We developed a simulation model for leaf area expansion of winter wheat under soil water stress based on soil column experiments and field studies under rainout shelters in Yangling, Shaanxi Province in China. First, a temperature response function was established. Then two soil water stress functions were established to describe the effects of water stress on leaf extension and senescence. Relative effective soil water content was used to describe the intensity of water stress, which is a function of three soil water related values (volumetric soil water content, the field capacity and wilting point of the soil). The first order derivative of a logistic function was used to describe the dynamics of leaf area of winter wheat, modified by temperature and soil water. The parameters of the newly established leaf area simulation model were estimated (calibrated) and then validated based on the data of soil column experiments in the 2014-2015 and 2015-2016 growing seasons, respectively. The model was further verified with the field experiments in the 2012-2013 and 2013-2014 growing seasons. The new model was also compared with the DSSAT-CERES-Wheat model. When relative effective soil water content was greater than 0.7, the leaf area expansion of winter wheat was not affected; when relative effective water content was between 0.2 and 0.7, water stress inhibited the leaf area expansion of winter wheat; when relative effective water content was less than 0.2, the value of water stress response function was negative indicating that the leaf area of winter wheat decreased. The root mean square errors (RMSE) between simulated and measured winter wheat leaf area were 9.8 cm2 plant-1 and 6.5 cm2 plant-1 for model development and verification, respectively. The RMSE of the new algorithm was 51% lower than the CERES-Wheat model, suggesting the results of this study provide a foundation for improving current models such as CERES-Wheat.