The crushing of leaves is the most time and effort-consuming part in DNA extraction which is a fundamental step in the study of molecular biology. In this study, a new rapid and batch-oriented crushing method for DNA extraction from maize leaves was developed. In addition, the practicability of the developed method in molecular marker-assisted breeding was verified using SSR molecular maker technology so as to provide a rapid, batch-oriented, low-cost and non-toxic leafcrushing method for a large number of molecular marker tests, improving test efficiency.
The leaf angle in waxy corn is a significant trait for breeding corn with compact plant type, which is beneficial to improve yield. According to the Griffing method II, the GCA （general combining ability） and SCA （specific combining ability） of leaf angle trait in the 7 waxy corn inbred lines and 21 combinations were esti-mated, and the genetic characteristics of leaf angle in corn were also analyzed. The results showed that among the 7 inbred lines, the GCA values ranked as N22 〉N8 〉 N28 〉 N7 〉 N23 〉 N27 〉 N4. The GCA of N27 showed great negative ef-fect, and the genetic variance of its SCA was lower. It suggested that the N27 can be used as an ideal parent for breeding excel ent combinations with smal leaf angle and compact plant type. The inheritance of leaf angle trait in waxy corn is in ac-cordance with the model of ＂additive - dominant - epistatic＂. The efficiency of leaf angle trait is control ed by recessive genes. The broad heritability of leaf angle trait in waxy corn is relative low （68.5%）, but its narrow heritability is relatively high （72.62%）. In the breeding practices, the early-generation selection is more suitable for the leaf angel trait.
