スイトウセンチュウの生態に関する研究 : 第4報 栽培環境によるイネの害徽及び籾内棲息密度の変動

抄録

According to the writers' previous reports it was supposed that the parasitic vitality of rice nematodes seems to be related with the cultural environment of rice plants in the paddy field. By the agricultural request, the writer studied the problem from the practical stand point, mainly the influence of the soil moisture, the high temperature, shaded condition and different dressing conditions. The present studies were done using the experimental pots from 1955 to 1957. The results are as follow ; 1. The parasitic vitality of rice nematodes in wet soil seemed to be remarkably lower than in impounded water. But when the seeds were sowed two days after injection of the water including nematodes in the surface of the wet soil, a considerably heavy injury occurred. 2. Although the injuries of the hills are stronger in the impounded water condition than in the wet soil condition, it was observed in both conditions that the higher the temperature becomes, the heavier is the injury of the hill. But on the other hand, after harvest the population density of the nematodes in unhulled rice is higher in the pots placed in the shade and covered with wersh-reed screens than in those piaced under high temperature condition within a greenhouse. 3. The influence on rice nematodes caused by the nitrogenous fertilizer, the calcium silicate and the urea is not distinct, but the injuries of rice plants in each pot ground-dressed with such fertilizers as ammonium sulphate, superphosphate of lime and potassium chloride tend to be rather stronger than those ground-dressed with only calcium silicate or with only urea sprayed on the leaves of the rice plants. However, the population of the nematodes in unhulled rice observed after harvest is similar in both cases.