幼苗飼育による虫害の品種間変動に関する研究 : I.イネカラバエに対する稲品種の抵抗性検定

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Recently the chemical control of injurious insects became remarkably effective but resistant varieties must be used as the basal practice in agriculture for the purpose of increase in yields of crops. Although the breeders have exerted themselves to originate resistant varieties but excellent results are not obtained so easily, bacause the factors relating to resistance have to be take out from various compound factors. Most of the main factors related to insect resistance must be hereditery, therefore it is considered that these factors are contained within the seeds of plants. If so, the insect resistance of varieties may be compared with each other by the method which makes insect injure seedlings in the stage before the weaning period. Namely, in this stage the seedlings are depending upon the nutrition of albumen only, but not no fertilizers in soil. In this standing the authors have studied the varietal difference of injury caused by the feeding or rice stem maggot which is known to have remarkable varietal difference. The adults used in this investigation were collected from the field in the beginning of October and then were reared on Agrostis matsumurae HACK. (A. perennans matsum. non TUCK. pro parte.), cereal weed till oviposition. The eggs laid on the surface of said weeds were floated on the water in an experimental dish, with the leaves. After about a week the larvae hatched out and fell into the water. On the other hand, the seedlings of rice plants in the stage before the weaning period were cultured under constant temperature. Thus the artificial parasitisms of the larvae on seedlings were conducted and the seedlings were moved into an incubator of 25℃ constant. The survivals and the body length of the larvae were surveyed about 10 days after artificial parasitisms because it was known, from the preliminary test, that the larvae reared on seedlings grew to the 3rd instar after 10 days from artificial parasitism. The results obtained are summarized as follows : 1. There were considerable differences in the survivals of each instar but it was clear that the coincidental tendency in the total survival percent and the percentage of individuals that grew to 2nd and 3rd instar larvae, and the correlation coefficient between these two percentages is 0.9401. 2. There were correlations between the total survival per cent (x) of larvae bred on seedlings and the number of injured panicles per 20 hills (y) of each variety observed in the field, and the correlation coefficients and the regression equations of each varietal group which was grouped by their heading date were r=0.8565 and y=45.76+1.17 x in early maturing varieties, r=0.9975 and y=1.25 x-7.96 in medium maturing varieties, and r=0.7088 and y=4.12+0.62 x in late maturing varieties, respectively. 3. The correlation coefficient between the total survival per cent (x) and the mean body length (y) of larvae bred on seedlings was 0.8273 and the regression equation was y=1.250+0.025 x, and this equation agreed with 99% probability in any groups of varieties. 4. The close correlation between the mean body length (x) of larvae bred on seedlings and the number of injured panicles per 20 hills (y) of each variety observed in the field was recognized, and the correlation coefficients and the regression equations of each varietal group were r=0.8540 and y=41.89 x-7.71 in early maturing varieties, r=0.5284 and y=39.90 x-40.58 in medium maturing varieties and r=0.8193 and y=22.16 x-19.74 in late maturing varieties, respectively. 5. From the observation on injured features of seedlings, the clear border of eating marks were recognized in the varieties on which larvae showed good growth, but in the varieties on which larvae showed inferior growth brownish and whitish borders in the eating marks or discolored leaves were observed. 6. According to these results, it is emphasized that this is a favourable method for originating resistant varieties to rice stem maggot attack becaus
日本応用動物昆虫学会の論文
1958-09-01

幼苗飼育による虫害の品種間変動に関する研究 : I.イネカラバエに対する稲品種の抵抗性検定

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