Abstract
In order to clarify the morphological and physiological causality responsible for the sterility in sunflower, the authors carried out histological observations on the male sterile plants as comparing with fertile ones. Fertile and male sterile inflorescences of sunflower (Helianthus annuus L.) 'P 21 ms' which inherit male sterility genetically, were used for this study. For histological observations, paraffin sections were cut to a thickness 15 μm and stained with the modifications of triple stain of Himes'es et al.. On observation with the behavior of tapetum during microsporogenesis, the sunflower studied in this experiment belong to the plasmodial type. After the microspore stage, distinguishable differences in the anther were observed. The tapetal cell wall of the fertile anther breaks down, and the tapetal protoplasm extruds into the anther loculus to envelop the microspores. On the contrary, tapetal cell wall of the sterile anther exists in situ and the tapetal cell increase in size. In addition, at both sites and shapes of tapetal nuclei at the microspore stage, a clear difference between the two types of fertilities could be distinguishable. As a result it is concluded that the abnormality of the tapetal cell lysis is closely related with male sterility. And it is also presumed that the sites or shapes of the nuclei were related with male sterilty. For the histochemical reactions, no conspicuous difference between the types of fertilities could be observed.
