Research On Characteristics And Energy Balance Of Maize Sap Flow In Semi-arid Area

Water is the basic element of agricultural production, corn transport water which was absorbed from soil, and transport resulting nutrients which was produted through photosynthesis, is the most important part of agricultural production.This paper research the photosynthetic rate and its impact factor on maize through the data been observed by LI-6400Portable Photosynthesis system, employing heat balance Dynamax packaged sap flow measuring system observe the sap flow of maize, combining the synchronize data of self-recording weather stations to study the discipiline of corn sap flow and its impact factor. Finally, on account of energy balance principle analysing the correlation between solar, wind energy and corn sap flow by comparing the the amount of solar、wind energy and the amount of corn sap flow.The main results were as followed:1.During the process of corn photosynthesis, the basic corn leaf net photosynthetic rate showed a single peak, net maximum photosynthetic rate appeared in13:00, the total photosynthetic rate of afternoon was higher than the morning, compare with the rate of photosynthetic solar radiation, net photosynthetic rate has a certain degree of "hysteresis". The correlation coefficient between Com leaf net photosynthetic rate and stomatal conductance、 intercellular CO2concentration、leaf temperature and photosynthetic active radiation were0.916,-0.882,0.899and0.930, photosynthetically active radiation has the greatest impact on net photosynthetic rate of maize leaves.2. There have a large difference in maize sap flow between day and night,maize sap flow basically stopped in night,but had slight sapflow,this phenomenon can supply water for waize which have high velocity transpiration in day. In rainy conditions,the maize sap flow velocity was smooth and steady all day long,the reason was that the net solar radiation and air temperature was relatively low.In cloudy conditions,the maize sap flow had significantly wave because of the lower net solar radiation.3. The correlation coefficient between maize sap flow work and wind energy which was absorbed by maize leaves was0.533,the regression equation between the two was Y=1695273+162.03X+5E-0.006X2+6.424E-8X3,and the fitting degree R2was0.348. The correlation coefficient between maize sap flow work and solar energy which was absorbed by maize leaves was0.948,the regression equation between the two was Y=-318197.7+1.237X-1.344E-7X2+6.494E-15X3,and the fitting degree R2was0.928.4. Solar energy not only supply energy for water vapor transfer in maize leaf intercellular,but also change the condition of maize itself and grow environment,for example, raised the temperature of maize leaves、reduced air humidity, this could speed up the transpiration of maize.Wind could speed up maize transpiration through flowed air away which had higher levels of vapor, but wind was not continued. Solar energy was main energy source of maize transpiration, wind energy had a certain degree acceleration to maize transpiration.