Abstract: By using thermal dissipation probe (TDP), the sap flow of Albizia kalkora in Yunmou dryhot valley of Southwest China was continuously measured in the typical months of dry and wet seasons in 2011-2012, and the soil moisture content and some meteorological factors such as photosynthetic active radiation (PAR), air temperature (T), atmospheric relative humidity (RH), water vapor pressure deficit (VPD), and wind speed were synchronously measured. The sap flow of the A. kalkora displayed an obvious variation pattern of high at day and low at night. In wet season, the stem flow velocity had obvious difference, with the mean value and peak value in sunny days being 2.8 and 2.4 times of those in cloudy days, and 7.5 times and 7.8 times of those in rainy days, respectively. The starting time of the sap flow in sunny days was about 3 hours earlier than that in cloudy days, and about 4 hours earlier than that in rainy days. In sunny days, the sap flow velocity was obviously higher in south side than in north side; while in cloudy days or rainy days, the sap flow velocity in south side was nearly the same as that in north side. As compared with those in dry season, the starting time of the sap flow in wet season was about 1.5 hours earlier, the peak hours of the sap flow were longer, the mean value and peak value of the sap flow velocity were 1.9 and 2.3 times higher, respectively, and the sap flux was about 2-3 times higher. The sap flow velocity was significantly positively correlated with the PAR, T, VPD, and wind speed, and negatively correlated with atmospheric RH, with the correlation coefficient in the order of PAR > VPD > T > atmospheric RH > wind speed.

Key words: EDTA, GA₃, Lolium perenne, Pb accumulation, subcellular distribution.