天狗巣病

The purpose of this study is to compare the chlorophyll content and the photosynthetic activity of the healhy paulownia tree with those of the diseased tree affected by withes'-broom, and to intend to explain the cause of the diseased paulownia's early death. The chlorophyll content was determined by Duboscq's colorimetric method and photosynthetic activity was determined by Warburg's micro manometric method. The results were as follows: 1. The chlorophyll content of the diseased leaves was always smaller than that of the healthy ones, and it was 46 per cent of that of the healthy leaves in July, 38 per cent in August, 48 per cent in September and 23 per cent in October. 2. The photosynthetic activity of the diseased leaves was always weaker than that of the healthy ones and it was 39 per cent of that of the healthy leaves in July, 25 per cent in August and 10 per cent in September. It is apparent that the photosynthetic activity of the diseased leaves decreases in proportion to the chlorphyll content of diseased leaves. This indicates that the whole leaves of a diseased shoot has a very weak photosynthetic activity comparing to that of a healthy shoot. While the previous experiment showed the abnormal increased respiration of diseased tree. It is certain, therefore, that one of the causes of the early death of the diseased tree is attributable to the unbalance between the photosynthesis and respiration, which leads the over-consumption of energy.