Varietal differences of the effects of daylength and temperature on the development of floral organs in the soy-beanI .Developmental stages of floral organs of the soy-bean.

Abstract

The authours intended to make clear the effect of day-length and temperature upon the development of floral organs and its varietal differences. In order to compare the development of floral organs, it is necessary to have a definite criterion on each developmental stages of floral organs. GUARD, A. T. (1931) reported general appearence of development o.f floral organs of the soy-bean, and also, KATO, I. et al. (1954) distinguished 13 stages on the developmental course of floral organs of the soy-bean. GUARD's description is rather rough in .the late developmental stages in spite of the precise description of the early developmental stages. In the description of KATO, I. et al., there are some incorrect points about the development of sepal and petal. In addition, the report of GUARD, A.T. and KATO, I. et al. lack the description of the bractlet formation . In these circumstances, the authors fclt necessity to make a new criterion of developmental stages of floral organs of the soy-bean. To deflne each developmental stages, the authors used the appea-.ance and formation of organs, and their definite morphological changes. In the early developmental course, bract, bractlet, sepal, petal, stamen and pistil appear in this order, and they continue to develop in parallel. Therefore, the authors divided the early developmental course into 8 stages ; bract formation stage, bractlet formation stage, sepal formation stage I, sepal formation, stage II, sepal fcrmation stage III, stamen-pistil formation stage I, stamen-pistil formation stage II, stam.en-pistil formation stage III. The middle and late developmental course were divided into 10 stages by the definite morphological changes of pistil which is the most important organ and in which the most distinguishable changes take place. Pictures of these stages are presented in Fig. 1∼Fig. 38. The defined stages are as follows : Stage O : As yet undifferentiated growth point (Fig.1) Stage I : bract formation stage (Fig.2) . The authors considered this stage as the first stage of flower primordium formation, since, before this stage, it is difficult to determine whether the process of flower primordium formation has already started or not, and before this stage the process is rather reversible. Stage 2 : bractlet formation stage (Fig.3)