Study Of Hydraulic Lift In Zygophyllum Xanthoxylum Of Eremophytes

Hydraulic lift under field condition has been a focus in the fields of plant Physiology-Ecology and Agriculture since it was first investigated in 1987. However, less attention was paid to in domestic desert plants. In this study, hydraulic lift of Zygophyllum xanthoxylum was investigated using the spilt-root equipment under field condition. The influence of hydraulic lift on the leaf potential, photosynthesis and soil available nutrients were also studied. The mechanism of hydraulic lift was also preliminary discussed. The major results were shown as follows:(1) Hydraulic lift of Zygophyllum xanthoxylum was confirmed. The condition of the hydraulic lift of Zygophyllum xanthoxylum was that the content of upper soil water and soil water potential dropped to 13.98% and-1.92MPa, the difference of upper and bottom soil water potential was-1.24MPa. The hydraulic lift occurred at 15:00-6:00. The quantity of hydraulic lift was 89.80g/2 plants·d.(2) Shading in daytime promoted hydraulic lift. When the aboveground tissues were cut, hydraulic lift occurred eventhough the upper soil water potential and soil water content was-1.92MPa and 12.67%, respectively. At the same time, difference of upper and bottom soil water potential was 1.82MPa. This result indicated that the mechanism of hydraulic lift could be explained by a "connection principle" in physics.(3) After hydraulic lift of Zygophyllum xanthoxylum, linear positive correlations were found between the soil water potential and leaf potential, and leaf water content (R2 was 0.8033 and 0.6362,p<0.001). Soil water potential also correlated positively to stomatal conductance, photosynthetic rate and transpiration rate (R2 was 0.9348,0.9098 and 0.9699, p<0.001). Hydraulic lift reduced the damage of water stress, improved stomatal conductance, photosynthetic rate and transpiration rate, it also contributed to the matter synthesis and accumulation and then the adaption of plants to drought stress was further improved.(4) Nutrentis in upper soil were activated by hydraulic lift. The available phosphorus the soil of 0-5cm away from the root system increased 29.48%,30.34% and 34.52% (p<0.05) compared to CK, the soil of 15cm and 30cm away from the root system, respectively. No significant changes were found in the contents of available nitrogen and available potassium.