Studies on Sterility in Barley : 9. Influence of starch accumulation in the filaments before anthesis on sterility.

Abstract

It has previously ken shown by the writer that a weak dehiscing power of anther is the most critical factor governing the sterility under several such environmental factors as high temperature, short day length, low phosphate level accompanied with high nitrogen application, acid soil, diseases, and so on. Accordingly it may be considered that amount of carbohydrates accumulated in the flowers should play important role to the incidence of sterility. In this experiment, amount of starch in the filament was microscopically estimated by the iodine method, employing florets just before flowering. Experimental materials were planted at two widely separated date in the spring, April 25 and May 25, and the resultant sterilizing percentages were 11.8 and 65.6 per cent respectively. Results are summarized as follows. 1. Irrespective of difference of planting date, there were not any starch reactions in the vascular bundle and its surrounding parenchyma cell of the connective and in the joint tissue lying between filament and connective (Fig. 2 and 3). 2. Starch reaction which has not yet been observed in the connective was noticed first at the top of filament, adjacent to near the base of the connective (Fig. 4 and 5). This reaction gradually increased, reaching a maximum level at a point about 70 p distant from the joint tissue and then is maintained at this level at the remaining lower parts of the filament. 3. Intensity of the reaction at the maximum level, relating the quantity of carbohydrates migrated into a flower, decreased with delay in sowing (Fig. 6 and 7). It appears likely that this decrease is attributed mainly to the rise in temperature. As sterilizing percentage has been proved to increase with late sowing, it is a matter of course that the reaction has a negative close correlation with it. 4. In the sterile plants starch reaction was blue in color showing the existence of amylose. On the other hand, in the fertile it is purpul red indicating amylopectin. Amylopectin is originated by branching from amylose molecule under the existence of "Q" enzyme. Consequently, it is considered that the activity of enzyme is lowered to some extent in the steril plants. 5. In view of these points, it can be said that poor starch migration into the filament from the vegetative organ at anthesis and falling of enzyme activity caused the failure of normal dehiscence of anther and subsequent male sterility in barley.