IMPROVING THE SIZE OF FORTUNE MANDARINE FRUITS BY THE AUXIN 2,4-DP

Fruit size is the most important limiting factor in the quality of cit rus fruits of the mandarin type. Use of the butylglycol ester of 2,4-d ichlorophenoxy propionic acid (2,4-DP) on the mandarin cultivar 'Fortu ne' immediately after the 'June drop' enhanced fruit growth and improv ed final fruit size. The increase in size with increasing concentratio n was linear with a saturation point between 50 and 100 mg l-1. Peel w eight and juice content per fruit were increased in absolute, but not relative values. Pulp components were examined and it was shown that 2 ,4-DP improved fruit size by affecting juice sac development through a n enhancement of cell enlargement rather than cell division.