Abstract:

Using the data from the automatic field microclimate observation station in winter wheat main producing areas in Northwest-Shandong Plain of China and the national meteorological observation station in Qihe from January 2019 to June 2022, the microclimatic characteristics of winter wheat fields in different growth stages were analyzed, and the difference of climate between two observation stations was compared.The results were as follows at various growth stages of winter wheat, the air temperatures at different layers, total radiation, photosynthetically active radiation (PAR), wind velocity, and soil temperatures at the depth of 5~20 cm all present an obvious unimodal diurnal variation and the diurnal variation of relative humidity is opposite to that of air temperature.Air temperature in wheat fields decreases and increases with the increasing height above the ground in the daytime and nighttime, respectively.The relative humidity is highest at the height of 30 cm above the ground in all growth stages and reaches the maximum in the nighttime at the late growth stage and in the daytime at the middle growth stage.Soil temperature in each layer is highest at the late growth stage, and their diurnal variations decrease with the increasing soil depth.Daily average air and soil temperatures in farmland are lower than those in Qihe station, and the daily average relative humidity in farmland is higher than that in Qihe station.Both the total radiation and PAR are strongest at the late growth stage.The wind speeds of all layers show the same change trend at the early growth stage of winter wheat, while the wind speed at the height of 60 cm is most intensively affected by the growth and development of winter wheat.The air temperatures and relative humidities at different layers and soil temperatures at the depth of 5~10 cm in farmland show obvious diurnal changes under different weather conditions at the middle and late growth stages, and the above-mentioned situation is the most obvious in sunny days, followed by cloudy days and the weakest in overcast days.

Key words: Northwest Shandong Plain of China, Winter wheat, Different growth stages, Microclimate characteristics of farmland