| In this research, the iron content of 53 opening pollinated varieties(OPVs), 227 inbred lines and 868 hybrid materials were tested by the atomic absorption spectrophotometer, and the materials with high-iron content were selected from various maize germplasm resources. 20 maize inbred lines were selected and made to match 99 crosses according to incomplete diallel design and all of them were sown in Ya'an and Xichang.The genotypic difference of iron and zinc content, combining ability, heritability, heterosis, parent-offspring correlation, the correlation between iron and zinc content, the correlation between iron(zinc) content and main agricultural and economic characters were studied. The results were as follows:1. The iron content of OPVs ranged from 10.9789 to 27.8734 mg/kg, with an average of 18.3599 mg/kg. The OPVs with the highest iron content were 211060,211025 and Jiku 2. The iron content of inbred lines ranged from 11.6094 to 32.7188 mg/kg, with an average of 19.6126 mg/kg. The inbred lines with the highest iron content were 9782, SAM3001 and Huang zao si.The iron content of hybrids ranged from 10.8619 to 38.0874 mg/kg, with an average of 18.5274 mg/kg. The hybrids with the highest iron content were Lao bai maize(250359),1308 and 170014.2. Combined analysis of variance in two locations showed that the effects of location, genotype, and their interactions were highly significant to iron and zinc content of maize hybrid crosses. In Ya'an, the iron content of 99 hybrid crosses ranged from 10.8432 to 32.2820 mg/kg, with an average of 19.4700 mg/kg. The zinc content ranged from 17.4768 to 42.5497 mg/kg, with an average of 26.2276 mg/kg. In Xichang, the iron content of 99 hybrid crosses ranged from 17.3212 to 43.4586 mg/kg, with an average of 28.8581 mg/kg. The zinc content ranged from 16.8962 to 43.3018 mg/kg, with an average of 24.2799 mg/kg.3. Analysis of GCA showed that the GCA opposite effect values of iron and zinc characters in different inbred lines varied greatly. The GCA of iron character in SAM3001, 9520 and 178, and that of zinc character in jinhuang96B and 4273 were relatively higher in two locations. Furthermore, in SAM3001, 178 and L790, both iron and zinc characters had relatively higher GCA.Analysis of SCA showed that the SCA opposite effect values of iron and zinc characters varied greatly too. The SCA opposite effect values of iron character ranged from-30.65 to 50.02 in Ya'an and from-29.99 to 25.54 in Xichang. The SCA of 43 crosses in Ya'an and 48 crosses in Xichang were positive. The SCA opposite effect values of zinc character ranged from-23.64 to 25.57 in Ya'an and from-15.08 to 28.47 in Xichang. The SCA of 50 crosses in Ya'an and 42 crosses in Xichang were positive. Analysis of opposite effect values of GCA and SCA showed that the crosses with high SCA had at least one parent with high GCA. However, in some crosses with high SCA, the two parents both had low GCA.This indicated that the SCA of crosses had a certain relation to the GCA of parents, but not completely determined by them.4. Analysis of heterosis of iron and zinc content showed that the mid-parent heterosis, over-high-parent heterosis and over-low-parent heterosis all varied greatly. Iron and zinc content both showed strong over-high-parent heterosis. Therefore, it is possible to improve the iron and zinc content of maize hybrids by choosing parents reasonably.5. In two locations, the narrow sense heritability of iron character were both very low, only 14.34% and 29.34%, while the broad sense heritability were 47.52% and 45.15% respectively. This indicated that iron character was mainly controlled by environment. Meanwhile, the narrow sense heritability of zinc character were 36.27% and 67.58%, while the broad sense heritability were 72.73% and 82.18% respectively. This indicated that zinc character was mainly controlled by genotype and also influenced by environment to some extent.6. Analysis of parent-offspring correlation showed that the iron and zinc content of hybrids was significantly and positively correlated with their female parents, male parents, high parents, low parents and mid-parent values. The parent-offspring correlation coefficients of iron content from high to low were mid-parent values, high parents, low parents, female parents and male parents, and that of zinc content from high to low were mid-parent values, high parents, female parents, low parents and male parents.This indicated that the iron and zinc content of hybrids related to their parents very closely. In order to improve the iron(zinc) content of hybrids, breeder should choose the inbred lines with high iron(zinc) content and mid-parent values.7. Analysis of correlation between iron and zinc content showed that the correlation between them was obviously or significantly positive, no matter in inbred lines or in hybrids, which suggested that it was feasible to improve the iron and zinc content at one time.8. Correlation analysis showed that the correlation coefficients between iron content and main agricultural and economical characters were not significant. The correlation coefficients between zinc content and plant height, ear height and kernel/row were positively and highly significant, which indicated that the hybrids with higher ear height, higher plant height and more kernel/row had higher zinc content. Meanwhile, the correlation between iron(zinc) content and yield was not close, which indicated that improving the iron and zinc content of maize could not lead to the reduction of yield. |
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