Nine-month-old ‘Pineapple’ sweet orange plants growing in 2.5-
L containers of a general purpose peat-based soil (Pro-Mix BX;
Premier Horticulture, Red Hill, PA) were maintained in a greenhouse
located at the Citrus Research and Education Center in Lake
Alfred, FL. Four weeks prior to the treatments, seedlings were cut
back to approximately 40 cm, and only one shoot per plant was
allowed to grow to approximately 20e30 cm in order to obtain 4e5
immature leaves