ISHS Acta Horticulturae 1020: VI International Cherry Symposium
N-SUBSTITUTED PHTHALIMIDES SHOW GIBBERELLIN-LIKE ACTIVITY IN INHIBITING FLOWER BUD FORMATION IN SOUR CHERRY (PRUNUS CERASUS L.) 'MONTMORENCY' |
| Authors: | J.B. Retamales, M. Bulatovic-Danilovich, M.J. Bukovac |
| Keywords: | cherry yellows virus, spur formation, GA3, blind wood, over-cropping |
| DOI: | 10.17660/ActaHortic.2014.1020.32 |
| Abstract:
Chemical control of flowering in sour cherry increases cropping efficiency. Flower buds on sour cherry are borne laterally on one-year-old shoots and spurs on older wood. As trees mature and encounter stresses, tree vigor decreases and often results in excessive flower bud formation on new shoots. These flower buds are pure flower buds that lack a vegetative meristem, and therefore the supporting nodes become blind after fruiting, resulting in reduced spur formation and loss of fruiting wood (blind wood syndrome). This condition is intensified by infection with cherry yellows virus. Our previous research demonstrated that gibberellic acid (GA3) can markedly reverse the blind wood syndrome by reducing flower formation and promoting spur formation on new shoots. N-substituted phthalimides (AC) are synthetic organic compounds that induce GA-like responses in several species. In trials over several years on young and mature sour cherry trees, we evaluated the relative activity of phthalimides (AC-377, AC-524, and AC-803) in comparison to gibberellins (GA1, GA3, GA4, GA7, and GA9) in virus-infected and virus-free plants. In mature virus-infected trees, AC-377 (5 x 10-4 M) was the most active phthalimide with similar flower inhibition to 1 x 10-4 M GA3 (63 vs. 59% flower inhibition). In young virus-free trees at two sites, lateral flower inhibition of 67-74% and 77-82% was observed with 5 x 10-4 M of GA3 and AC-377, respectively. When AC-377 was compared with various GAs at 1.5 x 10-3 M on mature virus-infected plants in two orchards, flower inhibition compared to the controls was 83% for GA3, 76% for AC-377, 51% for GA1, 47% for GA7, 36% for GA4, and 31% for GA9. These results demonstrate that N-substituted phthalimides, particularly AC-377, have equivalent activity to GA3 in virus-free and virus-infected sour cherry trees, and thus have potential to ameliorate the blind wood syndrome and increase the cropping efficiency of sour cherries. | |
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