Hydraulic Conductivity of Four Commercial Citrus Rootstocks1,2

The hydraulic conductivities of intact root systems of 4 commercial citrus rootstocks were estimated using a pressure chamber technique. The rootstocks used were rough lemon ( Citrus jambhiri Lush.), sour orange ( C. aurantium L.), Carrizo citrange [ Poncirus trifoliata (L.) Raf. × C. sinensis (L.) Osb.], and Cleopatra mandarin ( C. reshni Hort. ex TAN). Carrizo and rough lemon seedlings had the highest root conductivity, whereas Cleopatra and sour orange had the lowest root conductivity. Although these rootstocks as seedlings produce root systems in pots that differ from those in the field, some of the growth, yield, and drought resistance chartacteristics that have been previously assoicated with these rootstocks may be at least partially explained by the hydraulic conductivity of their roots.