Photoperiodic Pereception in Biloxi Soy Beans

Abstract

1. When whole plants of Biloxi soy beans are subjected to 8 hour photoperiods, initiation occurs if the intensity of light during the photoperiod is above 100 foot candles. Below 100 foot candles no flower primordia are initiated. 2. When plants are given an 8 hour photoperiod of natural light supplemented by 8 hours of Mazda light, initiation occurs if the intensity of the supplemental light is below 0.5 foot candle, but does not occur if the intensity is above 0.5 foot candle. 3. The stimulus that causes initiation of flower primordia at the growing points arises in the leaves and moves to the growing plants. 4. Flower primordia may be initiated at growing points that are kept, either in complete darkness or on photoperiods above the critical, provided the leaves are kept on short photoperiods. 5. Photoperiods shorter than the critical, applied directly to growing points, have no effect on flower bud initiation. Control of initiation is exercised only through application of photoperiods of proper length to the leaves. 6. Whether the responses secured in these experiments are due to a flower forming hormone or to other causes remains to be determined.