[Dependence of the gibberellin production of normal peas on the phytochrom-system]

Gibberellin bioassays of normal pea seedlings grown for the first 3 days after soaking of seeds in near red light and for the following 4 days under different light conditions had the following results: 1. The gibberellin content is the higher, the longer the plants grow under near red light. This light may be given continuously or intermittently (2.5 min/hour). The gibberellin depressing effect of uninterrupted darkness depends on when the dark period is given in the last 4 days before harvest. It is concluded that the gibberellinproduction has a lag-phase of about one day after light exposure. 2. Intermittent far red light results in a low gibberellin content even when every far red flash is preceded by a near red flash. On the other hand, near red light has the effect of a high gibberellin content even when a far red flash precedes every near red flash. Near red light cancels the effect of far red light and vice versa. The results prove that light influences the gibberellin content via the phytochrome-system.