Many areas in Hawaii with potential for growing macadamia lack sufficient rainfall. Ground water in these areas is generally brackish due to sea water intrusion. An experiment was started in 1984 to determine the response of young macadamia trees cv. `Kau' (HAES 344) Macadamia integrifolia to salinity under field irrigated conditions. Treatments were rain only, freshwater, 500 and 1200 ppm salt as diluted sea water to simulate the ground water conditions.
Until mid 1989 trees were irrigated twice weekly to supply 100% ET (evapotranspiration) of the previous week based on a class A pan. No differences were detected among treatments on yield, trunk diameter, soil and tissue nutrient composition except trees in the rain only treatment less yield and trunk growth. Irrigation treatments were modified in mid 1989 to rain only, and twice weekly fresh water, 1200 and 2400 ppm salt at 50 and 75%. ET. Effect on yield, trunk diameter, soil and tissue nutrient composition in the 1989-90 season will be reported.