Effects of Soil Bulk Density on ABA Concentration in Xylem Sap and Stomatal Conductance of Maize (Zea mays L.) Plant under Different Soil Water Conditions

The effects of soil bulk density on abscisic acid (ABA) concentration in xylem sap,stomatal conduc-tance (Gs) and transpiration rate (Tr) of maize (Zea mays L.) under different water conditions were studied.The results showed that ABA concentration in xylem sap in the drying plants was quintupling of that in witting plants,and became duplicate with 0.12 g·cm-3 increament of soil bulk density.Under same soil matrix potential,Gs and Tr descended with the increase of soil bulk density.And not soil bulk density but matrix potential had effect on leaf water potential.The results also indicated that ABA concentration in xylem sap increased and leaf Gs reduced when entire or part of root system in high compacted soil (1.45 g·cm-3).