ソルガムのヒエノアブラムシ抵抗性　葉面ワックスと栄養成分

The differences in the amounts of leaf surface wax and nutritional components such as sugar and free amino acids were compared among resistant (PE 954177), moderately resistant (IS 84) and susceptible (Redlan B) sorghum varieties to the sugarcane aphid. Melanaphis sacchari (Zehntner). (1) The kind of aphid appearing on the leaves of the sorghum varieties was only the sugarcane aphid, Melanaphis sacchari in the field. The number of aphids infesting a leaf was ca 0,30 and 3,500 in the resistant, moderately resistant and susceptible varieties at the middle of August, respectively. (2) The amount of leaf surface wax was approximately constant among these three varieties. (3) The total sugar content was slightly higher in the two resistant varieties than in the susceptible variety. (4) The total free amino acid concentration was higher in the two resistant varieties than in the susceptible variety. (5) These findings suggest that neither leaf surface wax nor nutritional components seem to affect the aphid populations on the leaves of the three sorghum varieties, showing that biogenic substances such as dhurrin, benzylalcohol, p-hydroxybenzaldehyde, aconitic acide, etc. may affect the aphid populations.