A series of experiments is described in which various growth regulators were applied in lanolin emulsions to the flowers of two pistillate varieties of strawberry, in an attempt to promote parthenocarpic development of their receptacles.
Parthenocarpic development was obtained in a large majority of the treated flowers over a range of concentrations, varying from 500 p.p.m. to up to 6,000 p.p.m., after treatment with the following growth regulators; 4-(indole-3-)butyric acid, 2-naphthoxyacetic acid, and 1-naphthaleneacetic acid.
Gibberellic acid promoted growth of the ‘neck’ region in Freya and increased the response of this variety to 4-(indole-3-)butyric acid. It also reduced the period of development of the fruit from anthesis till ripening.
An attempt to promote parthenocarpic receptacle development with 4-(indole-3-)butyric acid after the removal of all carpels before pollination was unsuccessful. It was concluded that the active growth substances probably stimulated growth initially in the tissues of the unpollinated carpels, which in turn promoted the development of the receptacle.