水分亏缺对温室覆膜滴灌番茄根系生长及吸水量的影响

The Effects of Water Deficit on Root Growth and Water Uptake of Mulched Greenhouse Tomato under Drip Irrigation

【目的】探讨水分胁迫和覆膜对温室滴灌番茄根系生长和根系吸水状况的影响。【方法】以20 cm标准蒸发皿的累计蒸发量(E_(p))为依据,结合地膜覆盖情况,设置3个处理:无膜高水处理(WM-0.9,水面蒸发系数为0.9)、有膜高水处理(FM-0.9)和有膜低水处理(FM-0.5,水面蒸发系数为0.5)。系统研究水分胁迫和覆膜双因素影响下的温室番茄根系分布特征,利用HYDRUS-1D软件模拟了根系吸水量,在此基础上,阐明了不同根系吸水量对番茄产量和水分利用效率的影响机理。【结果】WM-0.9、FM-0.9处理和FM-0.5处理在20 cm土层内的根长分别占总根长的58.6%、56.2%和78.9%。HYDRUS-1D模拟的各土层土壤含水率的均方根误差在0.010 cm^(3)/cm^(3)以内,回归系数在0.867~1.076左右,各处理蒸腾量与根系吸水量的均方根误差均在0.581 mm/d以内,回归系数在0.890以上,说明模拟值和实测值具有较好的一致性。FM-0.9处理的根系吸水量最多,达240.9 mm,比WM-0.9处理和FM-0.5处理分别高24.4%和26.7%,其中0~40 cm土层为番茄根系的主要吸水层,WM-0.9、FM-0.9处理和FM-0.5处理在该层的根系吸水量分别占总吸水量的84.2%、85.7%和83.2%,同时WM-0.9处理和FM-0.5处理在土层20~40 cm的根系吸水量迅速下降,FM-0.9处理则仍可保持较高的根系吸水量。FM-0.5处理的水分利用效率和灌溉水利用效率分别为59.0 kg/m^(3)和70.3 kg/m^(3),比WM-0.9处理高34.4%和55.5%,比FM-0.9处理高11.3%和30.4%;FM-0.9处理的产量最高,为147.7 t/hm^(2),较WM-0.9处理和FM-0.5处理高19.3%和23.6%。【结论】依据番茄根系对水分反应的差异,在0.9E_(p)的灌溉定额下,结合覆膜栽培技术,可提高深层土壤水分的吸收和利用。

【Objective】Facility vegetable production in China relies on drip irrigation with the seedbed mulched.How roots grow and its consequence for water uptake is an issue that is not fully understood.The aim of this paper is to investigate the change in root traits and water uptake of tomato under deficit irrigation,as well as the effect of initial soil water on demand of the crop for water.【Method】The experiment was conducted in a solar greenhouse,and the irrigation amount in each treatment was calculated based on the cumulative evaporation(E_(p))measured from a 20 cm standard evaporati o n pan installed inside the greenhouse.There were three treatments:irrigating 90%of E_(p) with the soil mulched(F M-0.9)and not mulched(W M-0.9)by plastic film,and irrigating 50%of E_(p) with the soil mulched(FM-0.5).In each treatment,we measured root distribution and change in soil water content.The root water uptake was calculated inversely using HYDRUS-1D,from which we analyzed the factors which impacted root water uptake as well as the consequence for fruit yield.【Result】Root length in the top 20 cm soil in WM-0.9,FM-0.9 and FM-0.5 accounted for 58.6%,56.2%and 78.9%of their total root length,respectively.The mean root square error of the soil moisture content simulated by HYDRUS-1D was less than 0.010 cm^(3)/cm^(3),and the regression coefficient between the measured and simulated soil water content was in the range of 0.867~1.076.The mean root square error of the measured transpiration and the simulated total root water uptake was less than 0.581 mm/d,and the regression coefficient between them was higher than 0.890.The largest root water uptake was in FM-0.9,totaling 240.9 mm,24.4%and 26.7%more than that in WM-0.9 and FM-0.5,respectively.Roots took most of the water the crop transpired from the 0~40 cm of soil,accounting for 84.2%,85.7%and 83.2%of the total transpiration for WM-0.9,FM-0.9 and FM-0.5,respectively.Water use efficiency and irrigation water use efficiency of FM-0.5 were 59.0 and 70.3 kg/m^(3),34.4%and 55.5%above that of WM-0.9,and 11.3%and 30.4%higher than that of FM-0.9,respectively.FM-0.9 gave the highest fruit yield at 147.7 t/hm^(2),19.3%and 23.6%higher that of WM-0.9 and FM-0.5,respectively.【Conclusion】Our experimental results showed that irrigating 90%of E_(p) combined with film mulching is optimal to increase the use of deep soil water for greenhouse tomato production.