| Maize is one of the main food crops in loess plateau, there is great significant toresearch the characteristics of corn and its influencing factors in loess plateau. In this paper,the sap flow rates of maize later growth period were measured with sap flow gauge based onheat balance method. and analyzed its characteristics of sap flow rates，impact factors, and thetranspiration of maize under different cultivation. The main results and conclusions are asfollowing:In the medium and later growth period, the plant stem flow rate had obvious day-nightrhythm, which had a big difference during the day and had a small difference an night. Amongthem, plant stem flow rate showed a single peak or board peak cyrve change in the sunny. Theplant stem flow rate showed an irregular multi-peak curve in rainy and cloudy weatherconditions. Diurnal changes along with the growth period of plant flow sap rate presents thetendency of diminishing, and large changes along with the fluctuation of environmentalfactors.The plant stem flow accumulation curve showed obvious "S" curve in different weatherconditions. The accumulation process of plant sap flow rate increased quickly from8:00to17:00, and then remained stable in sunny days. In rainy and cloudy weather conditions,accumulation process of it increased with time changing, and gradually decreases. Theaccumulation of plant stem flow rate was declined in the order of sunny days>cloudy days>rainy days, with the mean value being494.34,367.78,199.57g/d.The maize sap flow rates were affected by many environmental factors, among which,solar radiation and vapor pressure difference, relative humidity, air temperature showedsignificant correlations with it, the correlation coefficient respectively were as follows:0.888,0.880,0.820,0.693. There was no significant correlation with wind speed, the correlationcoefficient is0095. Above all, solar radiation was the most important meteorological factor inloess plateau.During the observation period, Plant stem flow was no significant correlation with soilmoisture content, and have better correlation with leaf area index and root hydraulicconductivity of the plants, the correlation coefficient as follows0.576and0.588, respectively..The results showed that the plant stem flow rate is not only influenced by environmentalfactors, also affected by their physiological characteristics. In the medium and the later growth period, in addition to the traditional cultivationpatterns A, the transpiration of pattern B、C、D was the main component of evapotranspiration,which account more than70%of the evapotranspiration. In the rest of cultivation patterns,single plant transpiration of pattern B was significantly higher than pattern C and D, while theratio of evaporation to field evapotranspiration of pattern B was lower than pattern C and D.From the perspective of the water use, pattern B was suitable for planting in loess tablelandarea with appropriate density, increasing fertilizer inputs, optimizing the ratio of soilevaporation to maize evapotranspiration. which can improved effective use of water andincreaced crop transpiration capacity.In the whole growth period, water consumption of plant had no significant differenceunder different cultivation patterns. WUE was mainly decided by the yield of maize.Reasonable density, balanced fertilization,mulching, and the selection of good varieties canincrease crop yield, improve water use efficiency of crop. |
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