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通过一种上干下湿的分根装置,应用中子水分仪在大田条件下研究了苜蓿和玉米根系提水作用测定中几种相关因素的作用和影响,提出了总提水作用的概念和测算模式.结果显示,夜间9 h(20∶00~5∶00)的表观根系提水量(Qm),一龄苜蓿为8.02 g,开花期的中单2号和豫玉22玉米分别为7.52 g和4.76 g.但其蒸腾失水量(Qt)平均分别为90.26 g4、6.94 g和48.07 g,供试土壤表面的自然蒸发量和上下土层之间隔水层的毛管升水量,苜蓿处理为6.60 g和6,58 g,玉米处理为5.20 g和6.66 g.分别占每株供试苜蓿表观根系提水量(Qm)的11.25倍、82.3%和82.1%,中单2号玉米的6.24倍、69.1%和88.6%,豫玉22玉米的10.1倍、109.2%和139.9%.表明被测植株的蒸腾速率、供试土壤表面水分的自然蒸发和隔水层的毛管作用对植物根系提水作用测定有着及其显著的影响.因此,植物总根系提水量QT应由实际提水量Qp与植株的蒸腾量Qt两部分构成,其中Qp为表观提水量Qm与上层土壤的蒸发量Qe之和再减去隔水层的毛管升水量Qc,即:QT=Qp+Qt=(Qm+Qe-Qc)+Qt.
The effect of several related factors on the determination of alfalfa and corn root water uptake was studied by using a neutron moisture meter on a field with the help of a root - (Qm) at 9 h (20:00 ~ 5:00), the first-year alfalfa was 8.02 g, and Zhongdan 2 and Yu-Yu 22 at the flowering stage were 7.52 g and 4.76 g, respectively, but the average evapotranspiration (Qt) was 90.26 g4, 6.94 g and 48.07 g, respectively. The natural evaporation on the soil surface and the amount of capillary flooding between the upper and lower soil layers were alfalfa treatments of 6.60 g and 6,58 g, and corn treatments were 5.20 g and 6.66 g, accounting for 11.25 times, 82.3% and 82.1% of the Qm, 6.24 times of Zhongdan No. 2 maize, 69.1%, 88.6%, 10.1%, 109.2% and 139.9% of Yuyu 22, respectively.The results showed that transpiration rate of tested plants, natural evaporation of surface soil moisture, And its significant impact.Therefore, plant total water QT from the actual amount of water Qp and plant transpiration Qt two Configuration, where Qp is the apparent water extract Qe amount Qm and the upper layer of soil and the minus evaporated water capillary rise Qc impermeable layer, i.e.: QT = Qp + Qt = (Qm + Qe-Qc) + Qt.