Abstract
'Hamlin' orange trees (Citrus sinensis (L.) Osb.) were used to assess the effects of nutrition and irrigation on freeze hardiness. A 3 × 3 factorial experiment, with three irrigation schedules based on the presence or absence of growth flushes and soil water depletion (SWD) and three fertilizer application frequencies at the same annual rate, was conducted in 1994 and 1995. Freeze tests using the electrolyte leakage method were conducted at 26.6, 21.2, and 15.8ordm;F. Neither SWD nor fertilizer application frequency had a significant effect on tree height or trunk diameter. However, timing of the second growth flush during 1994 was significantly delayed for trees maintained at 45% SWD and leaf freeze hardiness increased in the winter of 1994. Application of fertilizer through Jan. did not decrease leaf freeze hardiness as is commonly believed in the citrus industry.
