Quantifying the contribution of meteorological factors and plant traits to canopy interception under maize cropland

A thorough understanding of crop canopy interception is crucial for understanding the relationship between water management and agriculture in water-limited regions. The factors that influence the interception process, such as meteorological conditions and plant traits, are diverse and uncertain. We divided meteorological factors and plant traits into three groups: precipitation-related meteorological factors (including precipitation event factors and raindrop factors), non-precipitation-related meteorological factors (air temperature, relative humidity, wind speed, etc.) and plant traits (leaf area index (LAI) and mean leaf inclination angle). The contributions of groups and each variable were then quantified with respect to canopy interception. This study was based on data from 80 events over four years (2017–2020). Measurements were taken under maize (Zea mays L.) cropland located on the southern Loess Plateau. The canopy interception (Ic) was calculated as the difference between precipitation and the sum of throughfall and stemflow and all of Ic was assumed to be lost to evaporation in the study. Results showed that the cumulative Ic of the 80 events was 395.9 mm, accounting for 39.7% of the contemporaneous total precipitation, but the mean proportion of canopy interception during each precipitation event (Ic percentage) was greater at 57.6% because of the high interception percentage during light precipitation events (0–5 mm, totaling 37 events). Pearson correlations analysis revealed a significant positive correlation between Ic and precipitation-related meteorological factors (including precipitation amount, duration, raindrop diameter (D50), terminal raindrop velocity (UV) (p < 0.01) and intensity, average downward force (F0) (p < 0.05)), whereas there was a significant negative correlation between Ic percentage and precipitation-related meteorological factors (p < 0.01) because precipitation amount was more affected by precipitation-related meteorological factors. When the results of different groups were compared, precipitation event factors (amount, duration and intensity) and raindrop factors (D50, UV, F0,) made the highest contribution to explaining Ic (56.4%) and Ic percentage (28.3%), respectively. Both the unique effect and individual importance of plant traits to Ic and Ic percentage increased when considering the precipitation events which occurred close to the LAI measurement date. It is essential that short-term assessments are used if considering LAI in relation to Ic. Precipitation amount had the largest individual importance on Ic (30.2%, p < 0.01), whereas D50 was the analogous variable for Ic percentage (9.5%, p < 0.05). Our results confirmed that interception by the maize canopy accounts for an important portion of the total field water input. The data and information on the interception process presented in this study, should contribute to the understanding of the overall water balance in agroecosystem environments and improve knowledge of the interplay between agroecosystems and the environment.