Tiantian Hu
College of Water Resources and Architectural Engineering, Northwest A & F University

Effects of partial root-zone irrigation (PRI) on the hydraulic conductivity in soil-root system (Lsr) in different root-zones were investigated using a pot experiment. Maize plants were raised in split-root containers and irrigated on both halves of the container (conventional irrigation, CI), on one side only (fixed PRI, FPRI), or alternatively on one of two sides (alternate PRI, APRI). Results show that crop water consumption was significantly correlated with Lsr in both the whole and irrigated root-zones for all three irrigation methods but not with Lsr in the non-irrigated root-zone of FPRI. The total Lsr in the irrigated root-zone of two PRIs was increased by 49.0-92.0% compared to that in a half root-zone of CI, suggesting that PRI has significant compensatory effect of root water uptake. For CI, the contribution of Lsr in a half root-zone to Lsr in the whole root-zone was about 50%. For FPRI, the Lsr in the irrigated root-zone was close to that of the whole root-zone. As for APRI, the Lsr in the irrigated root-zone was greater than that of the non-irrigated root-zone. In comparison, the Lsr in the non-irrigated root-zone of APRI was much higher than that in the dried zone of FPRI. The Lsr in both the whole and irrigated root-zones was linearly correlated with soil moisture in the irrigated root-zone for all three irrigation methods. For the two PRI treatments, total water uptake by plants was largely determined by the soil water in the irrigated root-zone. Nevertheless, the non-irrigated root-zone under APRI also contributed to part of the total crop water uptake, but the continuously non-irrigated root-zone under FPRI gradually ceased to contribute to the crop water uptake, suggesting that it is the APRI that can make use all the root system for water uptake, resulting a higher WUE.
Key words: Partial root-zone irrigation, hydraulic conductivity in soil-root system (Lsr), soil moisture, soil water uptake, crop water consumption