Traits Related To Mechanical Harvesting And Their Association Analysis With SNP Markers In Maize Inbred Lines

Mechanical harvesting is important for corn production. While high grain moisture content of the maize and lodging at the harvest time are important factors limiting mechanical harvesting. By studying the grain water content, grain natural dehydration rate and stem strength of maize inbred lines, in connection with genetic association analysis, the current research is expected to find SNPs that provide the basis for mechanical harvesting and for corn germplasm improvement and molecular marker assisted breeding.1. Evaluation system of the maize grain moisture content, grain natural dehydration rate and stem strength at physical maturity were established. Standardized numerical range and the estimate range of properties were used to make classification and evaluation of maize inbred. The evaluation system would have a certain value in the practical breeding and future research.2. Maize grain moisture content at physical maturity was significantly and positively related to bracts layer and had significantly negative correlation with the number of days from pollination to full ripeness, the number of days from seeding to pollination and hundred grain weight. Grain natural dehydration rate had significantly negative correlation with ear thick, bract length, vitreous area ratio, the number of days from pollination to full ripeness,sowing to pollination, and sowing to full ripeness as well as stem stretching resistance. The grain natural dehydration rate and the thin layer drying rate had similarities, and were both affected by the grain size and texture. Stem strength at physical maturity primarily significantly related to the number of days from pollination to full ripeness, sowing to full ripeness, sowing to pollinate, ear length, vitreous area percentage, hundred grain weight and bract length.3. According to the results, this research established the structure model that suitable for thin-layer drying of maize grain and selected characteristics of maize inbred that suitable for mechanical harvesting. Grains that are appropriate small, long and flat, with relatively large proportion of opaque part and with opaque part at the top seeds were easily to dry. Maize inbred suitable for mechanical harvesting should have the following characters: longer daysfrom pollination to mature, shorter bracts, less layers of bract, longer ear and thinner axis,longer and flat grains, higher vitreous area percentage, better lodging resistance and the top of grains were opaque.4. The SNP whose-Log(p) value was higher(MLM model) and genetic typing was good was considered to be more important. Research results, 24 SNPs related to GM at physical maturity, with 10 important ones, located on chromosome 5、10 and 6. 23 SNPs associated with GDR at physical maturity, with 4 important ones, located on chromosome 3、8 and 4. 30 SNPs associated with stem strength at physical maturity, with 10 important ones,is located in chromosome 6 、 4 、 5 and 1. 53 SNPs related to the number of days from pollination to full ripeness SNP, with 18 important ones, located on chromosome 1、3、4、and5 chromosome, and mainly located on chromosome 3 and 1. 31 SNPs associated with vitreous area percentage, with 20 important ones, are mainly distributed on chromosome 7、6、5、4 and 2.5. Comments for the important SNPs. The genes linked with three SNPs(SYN28825、SYN36685 and PZE-105093835) associated with GM at physical maturity and two SNPs(SYN13065 、 PZE-105068038) associated with GDR at physical maturity were mainly associated with seed vigor in the process of dehydration, the protection of biological membrane, cellular homeostasis maintenance, and took important role in the thermal resistance to drought stress of seeds of maize inbred. The genes linked with two SNPs(PZE-104088422 、 SYN21311) that related to stem strength at physical maturity mainly associated with the growth of root cells, anti-aging and drought resistance. The genes linked with 5 SNPs(SYN10108、PZE-101222445、SYN16563、PZE-105049957 and SYN19158)that associated with vitreous area ratio, mainly associated with the metabolism of starch and protein in the endosperm. The genes linked with 2 SNPs(PZE-101105558 and SYN423) that associated with the number of days from pollination to full ripeness, mainly related with seeds and root development, regulating the growth of plants under adversity. But the function of genes that linked to SNPs found still need further research and exploration.