A Dynamax sap flow measuring system consisted of heat balance sensors was used to continuously monitor sap flows of corn(Zea mays) on Horqin sandy land

Northeastern China.The photosynthetic active radiation

air temperature

relative humidity and wind velocity were recorded synchronously by an automatic weather recording system.Based on the manual records of weather conditions

four most representative weather conditions were gathered up to analyze the relationship between sap flow

water consumption and meteorological factors.The results showed that the diurnal variations and affecting factors of sap flows differed with weather conditions.However

the photosynthetically active radiation was always the dominant factor affecting the sap flow.The diurnal sap flow changes of corn showed board peaks or single-peaked curves in sunny days

multiple-peaked curves in cloudy days

and single-peaked or irregular multiple-peaked curves in windy day and rainy day.The diurnal variations of sap flows resulted from comprehensive effects of multiple meteorological factors.The water consumption for an individual corn plant was the highest in sunny days

followed by windy days

cloudy days

and rainy days

with means of 588

401

399

and 305 g/h

respectively.