Relationship between Gramine Concentration and Cereal Aphid Polulations in Seedling and Maturation Stages in Barley Lines

The relationship between the indole alkaloid gramine concentration and aphid population was examined seedling and maturation stages in 14 barley lines of Hordeum spontaneum and H. unlgare. The density of Schizaphis graminum did not differ significantly with the gramine concentration in the seedling in the greenhouse. However, the population of Rhopalosiphum padi sometimes differed with the seedling. The plant resistance to the natural infestation of cereal aphids was obvious at the heading stage. There was a negative correlation between the high population density of aphids and gramine concentration. The gramine concentration was high in matured resistant resistant lines, especially wild lines, as compared with susceptible lines due to higher biodegradation activity.