Effects of girdling time on growth, yield, and fruit maturity of the low chill peach cultivar Flordaprince

Low chill Flordaprince peach trees in subtropical Australia were trunk-girdled at 1 of 3 times during fruit development: pre stone hardening (pre SH), post stone hardening (post SH), and 2 weeks before expected first harvest (BFH). Measures were made of fruit and shoot growth, harvest data, and starch levels in different tree parts.

The pre SH girdling gave the greatest (P < 0.05) increase in fruit size during stage 2 of fruit development, and pre and post SH girdling treatments gave progressively earlier (P < 0.05) and shorter (10 days v. 24 days for control) main harvest period. Girdling resulted in greater numbers of fruit of larger, desirable marketable size (> 90 g) than the control, although the latter caught up in average yield because of longer development period and some variability in numbers of fruit per tree. Split pip was not a problem. Fruit sugar content was significantly (P < 0.05) higher with post SH and BFH girdling treatments than with control or pre SH treatment. Girdling temporarily increased starch levels in the leaves and shoots and reduced shoot growth.