采用分根装置，在均匀灌水、固定部分根区灌水和根系分区交替灌水3种方式下，分期测定玉米的耗水量、两个1/2根区及整个根区的土—根系统水分传导与土壤含水量，研究各个根区在作物水分吸收中的作用。结果表明，3种灌水方式下，玉米耗水量与全部根区和灌水区土-根系统水分传导间均存在密切的正相关关系。均匀灌水条件下，1/2根区水分传导约占全部根区水分传导的一半；固定灌水条件下，灌水区占全部根区水分传导的比例远大于非灌水区，与全部根区接近。交替灌水条件下，两个根区对全部根区水分传导的贡献呈交替变化，其非灌水区占全部根区水分传导的比例较之固定灌水明显增大。全部根区土-根系统水分传导与灌水区土壤含水量明显相关，灌水区土壤含水量决定了整株作物的水分吸收情况。交替灌水的非灌水区从土壤到根系仍有一定的水分传输作用，而固定灌水的非灌水区使全部根区的土—根系统水分传导降低。
Partial rootzone irrigation can reduce water consumption and enhance water use efficiency. Compared with conventional irrigation, partial irrigation may reduce total biomass production, but will bring no loss of economic yield and even improve the quality of grains. While considerable expertise of partial irrigation is being developed, very little work has been conducted to understand how the uptake of water are affected when part of the root system is consistently or alternately exposed to watering and drying during their growing season. The present study was aimed to study the functions of different rootzones in water uptake under localized irrigation on maize grown in split-root containers. Maize was irrigated in both halves of the pot (control, C) or water was continuously supplied to the one-half of the pot and the other half kept dry (fixed partial rootzone irrigation treatment, F), or water was alternatively supplied to two halves of the pot for 10 days each (alternative partial rootzone irrigation treatment, A). These treatments lasted forty days in total and were divided into four treatment periods. For all three treatments, the amount of water consumption by maize, soil-root hydraulic conductivity from the whole rootzone and two half rootzones, and the soil water content from different rootzones were measured at fifth and tenth days during each treatment period. The hydraulic conductivity in soil-root system was measured using the pressure chamber. The results were as follows. For all treatments, water consumption by maize was significantly linearly correlated with soil-root hydraulic conductivity from the whole rootzone or irrigated rootzone, suggesting that crop water consumption can be represented by soil-root hydraulic conductivity from both the whole and irrigated rootzones. For the control, the percentage of hydraulic conductivity from one half rootzone was about 50% of that from the whole rootzone. For F treatment, the percentage of the irrigated rootzone was markedly higher than that of the non-irrigated rootzone and nearly reached 100%. As for A treatment, the percentage of two half rootzones alternatively changed, and the percentage of the irrigated rootzone always surpassed that of the non-irrigated rootzone. The percentage of the non-irrigated rootzone of A was much higher than that of F treatment. These indicated that for conventional irrigation, both two half rootzones contribute to water uptake by crops, while for F irrigation, only the irrigated rootzone does, for A irrigation, mainly the irrigated rootzone does and also the non-irrigated rootzone does some. For all treatments, soil-root hydraulic conductivities from the whole rootzone and irrigated rootzone were both significantly linearly correlated with soil water content of the irrigated rootzone, and the slopes were different among them and among different irrigation methods. Comparative analysis of these slopes confirmed the function of different rootzones in crop water uptake under different irrigation methods. The variance of the slopes for F treatment also pointed out that the non-irrigated rootzone decreased the hydraulic conductivity in soil-root system from the whole rootzone under fixed partial rootzone irrigation.
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