本文引进了一个新的记号，研究色多项式的根全为非负整数的图的色性。

In this paper, a new character is used. When all roots of chromatic polynomials of graphs are not minus integers, the author studies the chromaticity of them.

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结果表明：（1） SAB- 3根系发达，叶色深绿，丰产性好，抗性强，营养生长期较长；

The results showed: (1) SAB 3 had the characters of strong root system, dark green leaves, high yield potential, good resistance and longer stage of vegetative growth.

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