Abstract: Two quality protein maize populations (C. Pop 14QPM and Shaanzong 5QPM) and five classes (1, 2, 3, 4, 5) of endosperm hardness were used to study ultra-microstructure and chemical analysis of their kernels. Results indicated that the harder the endsoperm was, the better the physical characters were and the poorer the protein quality of kernds was. Under the opague-2 background, the differences of kernel density and endosperm hardness mainly experessed in internal endosperm tissue. Kernel physical characters were influenced by cell distribution, shape, homogeneity and texture of starch granules in internal endoperm tissue. Nutrition quality was influenced by the distribution, density and morphology of matrix protein, and the compact degree between starch granules and matrix protein.

Key words: Opaque-2 maize, Kernel, Starch granule, Endosperm ultra-microstructure, Matrix protein