Study On Important Physiological Characters Evolution Law Of Maize Elite Inbred Lines And Its Derived Lines

Maize elite inbred lines play a critical role in maize breeding; however, there was lack of system research on agronomic traits and physiological traits in the process of its evolution. For this reason, the study were carried out from 2007 to 2008 in main maize production region of china, and the important physiological traits and indoor analysis experiments were conducted in state key laboratory of crop biology of Shandong Agricultural University. To explore evolution law, Huang zaosi and its derived lines, Mo17 and its derived lines, Ye478 and its derived lines and maize hybrid were used as experiment materials at grop for the change of yield, photosynthetic characteristic, plant traits, disease resistance and ecological adaptability of derived lines in the process of evolution of elite inbred lines. The main results were as follows:1 The change of photosynthetic characteristic of elite inbred line and its derived linesDeclined photosynthesis rate of new hybrid was lower than old,but Pn of new hybrid increased significantly than SD19. There was significantly genotypic difference in Pn of different inbred lines, while there existed inconsistent difference of different derived lines; Pn of Huang Zaosi was higher than improved or separated lines, and lower than backcross improvement lines, single cross lines and Double cross lines; although Pn of Mo17 and its derived lines was higher than Huang Zaosi and its derived lines, there is no significantly difference in Pn between Mo17 and its derived lines, displaying genetic stability.There were differences significantly on leaf areas among every hybrid, which of ND108,ZD958,YD13 increased by 38.57%,21.87%,18.97% in comparison with SD19 respectively, and the high leaf areas of new hybrid were lasting longer than old. The leaf areas of Huang zaosi and its derived lines represented Double cross lines > single cross lines > the backcross improvement lines > Huang zaosi, and the derived lines pass through succession into high leaf area value phases that were long lasting. For Mo17 and its derived lines, the leaf areas were higher than Huang zaosi and its derived lines. Mo17 was higher than its derived lines on the leaf area before milk phase,however, it was becoming lower than that of single cross lines and the backcross improvement lines after a milky phase.Huang Zaosi, a typical non-stay-green elite inbred line, was lower than its derived lines for chlorophyll content; Mo17, whose chlorophyll content is higher than Huang Zaosi, is stay-green elite inbred line. And chlorophyll content of Mo17 reduced faster than its derived lines at latest stage, which was because its derived lines inherit stay-green characteristic, and chlorophyll content of its derived lines reduced slowly.Huang Zaosi with low chlorophyll content(1.52².63mg·g^-1·FW), was a typical non-stay-green elite inbred line, chlorophyll content of whose was lower than its derived lines; chlorophyll content of Mo17 (2.11³.89 mg·g^-1·FW), a stay-green elite inbred line, was higher than that of Huang Zaosi, and reduced faster than its derived lines at latest stage during its derived lines inherit stay-green characteristic and reducing chlorophyll content slowly.2 Yield and dry matter accumulation of elite inbred lines and its derived lines2.1 Yield traits of elite inbred lines and its derived linesBoth yield traits and plant characteristics of hybrids were presented to illustrate heterosis, containing yield improving, 1000-grain weight increasing, while other traits changed little. Growth period of hybrids prolonged and enhanced on the percentage about after anthesis in total growth period. The growth period of Huang zaosi was very short, while its derived lines extended gradually; Ye478 was longer on growth period, while its derived lines shorten. It could provide yield advantages for the derived lines of all elite parents due to the increase of growth period percentage on after anthesis in total growth period. For plant height and Ear Height in maize, Mo17 was high, while its derived lines lowered step by step; differently with Mo17, Ye478 was low, while its derived lines rose step by step. On the whole, ear row numbers rose in elite parents and their derived lines gradually, while little change existed owing to inheritance stability in elite inbred lines and its derived lines, such as ear diameter and ear kernels in Huang zaosi, and ear length in Mo17 and Ye478.2.2 Matter accumulation and Partitioning of elite parent and its derived linesBiomass, gain yield, harvest index increased in hybrids, and the highest heterosis index were noted in gain yield. It was heighten on leaf weight, stem weight, axis weight, biomass, grain yield about Huang zaosi'derived lines in the course of evolution, while harvest index declined, which was the most strongly disadvantaged for yield . For Mo17, it was high on leaf weight, stem weight, biomass, grain yield, harvest index of elite parent, only was little fall founded on its derived lines. The derived lines of Ye478 were lower than its elite parent on biomass, but whose grain yield and harvest index was higher. Based on study above, the conclusion was showed that it could provide a key avenue for raising more yields of inbred lines through the improvement of biomass yields when harvest index was high. 3 Ecological adaptability of elite parent and its derived lines3.1 Ecological adaptability of yield traitsKernels per ear of hybrid were the highest in Harbin among all experiment sites, and the lowest in Yaan. Kernels per ear of Huang Zaosi were the biggest in Taian, but the difference was small beween Taian and Harbin. Mo17 has a strong ecological adaptability on kernels per ear based on not being significant difference in three experiment sites. Ye478 was selected and bred from Agricultural Science Institute at Laizhou, the derived lines of whose owned the biggest on kernels per ear in Taian, the smallest in Yaan, and had impact on weight per 1000 kernels that the biggest was Harbin, the smallest Yaan.3.2 Ecological adaptability of plant traitsPlant height and stem diameter in Huang Zaosi, Mo17, Ye478 and their derived lines, and hybrid were higher in Taian than that in Harbin, at the same time, ear heights on Huang Zaosi, Ye478 and their derived lines were higher in Taian than that in Harbin; all plant traits were the lowest in Yaan that ranked the smallest coefficient of variation for plant height, the biggest coefficient of variation for ear height, maintained stability strongly on plant height, to some extend, it also illustrated the influence on ear height which such factors as the external environment.