Relationship of winter wheat phenology with carbon and water flux and influencing factors in the North China Plain

• Published in: Computers and electronics in agriculture 2024-07, Vol.222, p.109034, Article 109034
• Main Authors: Wu, Jiujiang, Wang, Nan, Xing, Xuguang, Ma, Xiaoyi
• Format: Article
• Language: English
• Subjects: Ecological water use efficiency; Net primary production; North China Plain; Phenology; Winter wheat
• ISSN: 0168-1699; 1872-7107
• DOI: 10.1016/j.compag.2024.109034

•Winter wheat carbon and water fluxes exhibit spatial heterogeneity.•Ecological water use efficiency determined by NPP, not ET.•No consistent pattern between winter wheat growth period and NPP identified.•VPD crucial regulatory factor of carbon and water fluxes in winter wheat. Evaluating the relationship between plant phenology and the carbon–water cycle is essential to understanding regional ecological functional mechanisms and formulating ecological management policies under climate change. The North China Plain (NCP) is a region where more than half of the land area is devoted to winter wheat cultivation. Thus, this study aimed to investigate the factors influencing carbon–water flux and its relationship with winter wheat phenology in the NCP. Carnegie–Ames–Stanford Approach model was used to evaluate winter wheat net primary production (NPP), the evapotranspiration (ET) of winter wheat was calculated using the Penman–Monteith equation, and the ecological water use efficiency (EWUE) was calculated as the NPP to ET ratio in this study. We found that winter wheat with different phenological dates, NPP, ET, and EWUE exhibited spatial heterogeneity in the NCP. The growth period of winter wheat increases from south to north, and the areas at which advanced green-up, heading, and maturity are observed accounted for 81.8 %, 73.6 %, and 51.3 % of the total area, respectively. During the growth period of winter wheat, EWUE increased over time (0.01 g C/m−2(−|-) mm−1 year−1); this was mainly because the increase of NPP (0.469 g C/m−2(−|-) year−1) was greater than the increase of ET (0.44 mm year−1). In different temperature and precipitation zones, growing season length was positively correlated with ET although no consistent NPP pattern was identified. The effects of climate and phenological length on NPP and ET differed by phenological stage and in arid areas. However, generally, vapor pressure deficit was a key regulatory factor of carbon–water flux in winter wheat, indicating that climate factors mediate the transpiration and photosynthesis of winter wheat by influencing vapor pressure deficit to regulate leaf stomatal opening and closing. Our results have implications for regional policy making and field management.