ROOT-GROWTH AND WATER STATUS OF CONTAINER-GROWN PHOTINIA X FRAISERI DRESS TRANSPLANTED INTO A LANDSCAPE

Photinia plants produced in 11.4-liter polyethylene containers using a pine bark-based medium were transplanted into a well-drained sand and irrigated on alternate days. Polyethylene barriers were placed under half the root balls at transplanting to limit gravitational water loss . Plant water potential was measured diurnally between irrigations, an d root growth was determined at 4-month intervals. Plants with barrier s averaged higher cumulative daily water stress than control plants ov er the year, although predawn and minimum water potentials were-simila r. Growth index and trunk diameter were similar for the plants over ba rriers and controls, but the former were taller after 1 year. Plants w ith barriers had twice the horizontal root growth into the landscape s ite as control plants, resulting in twice the root mass in the landsca pe after 1 year.