| This study using 2n gametes sexual polyploidization and distant hybridization created a heterologous nearly hexaploid (MTP-74,2n=74) and a heterologous nearly octaploid (MTP-94,2n=94), containing three species chromosomes of maize, tripsacum and teosinte. Using these two allopolyploid as female parent hybridization with tetraploid perennial teosinte (9475,2n=40) respectively, we obtained the MTP74 hybridization groups and the MTP94 hybridization groups. The cytology, morphology, biological yield and heterosis of these groups were studied, the main results as follows:1 By using the method of two-color GISH, we identified the number of chromosomes and the composition of chromosomes of MTP74 hybridization groups materials. A total of 19 materials were successfully identified. The chromosomes range of MTP74 hybridization groups was 54-58. The offspring contains maize,9475 and TZ07 chromosome number ranges were 7-13,26-33 and 14-18,the averages were 9.79,30.00 and 16.11 respectively, In MTP94 hybrid groups, a total of 19 materials were successfully identified. This group of chromosomes range was 47-87, offspring contains the chromosome number of maize,9475, and TZ07 ranges were 7-16,32-42 and 14-18.the averages were10.00,38.58 and 16.21, respectively.2 By analyzing the correlation between agronomic traits and yield in two groups, it was observed that plant height, grass length, leaf area and leaf number were significant or extremely significant positive correlation with the total fresh weight, indicating that these four traits were likely to be basic characteristics of forage maize yield. Because the two hybrid progenys population belong to more tillers forage maize population, when the tiller number reaches a certain value, tillering and stem thick exist certain negative correlation. Therefore, in the more tillering perennial forage materials, there was no significant correlation between tillering and stem diameter with biomass yield.3 The Heterosis Analysis of two groups of materials showed that in the MTP74 and MTP94 hybrid population materials, their fresh yield, hay yield, plant height, grass length showed transgressive heterosis; leaf number, stem diameter, tillering and leaf area had mid parent heterosis. In MTP74 hybrid groups, there were 11 materials of eight traits fully showed the positive in heterosis; the highest material about transgressive advantage is P-08, which transgressive advantage had seven positive traits phenotype. In MTP94 groups,15 materials of eight characters in the whole performance were positive in heterosis and there were 3 materials (PP-11, PP-12, PP-21) that were the highest transgression advantage which their transgression advantage had six positive traits.The results suggest that MTP-74 and 9475 hybridization or MTP-94 and 9475 hybridization could improve the heterosis of hybrid progeny,and both been used as forage maize breeding parents bridge.4 Through comparative analysis nine characters mean of MTP74 and MTP94 hybrid groups showed that total number of chromosomes exist significant differences between two groups, MTP94 groups from tetraploid perennial teosinte had significantly higher chromosome than MTP74 hybrid groups. There was no significant difference about plant height, grass length, tillering number, stem diameter, leaf area, leaf number, total dry weight and total fresh weight in two groups. The improvement of Plants ploidy had a certain influence to material properties of offspring, but the effect was not unlimited increase with increasing of. When plants ploidy reached a certain degree, decided to individual traits and yield variation depends on the individual inner chromosome recombination, gene exchange and interaction between the nuclear mass.5 Analysis the variable coefficient of agronomic characters and fresh, dry production in the two groups showed that in the MTP94 hybrid groups, the variation coefficient of five traits including plant height, grass length, stem diameter, total dry weight and total fresh weight were significantly higher than that of MTP74 hybrid groups. On leaf area, the variation coefficient on MTP74 of hybrid groups was significantly higher than MTP94 hybrid groups. On the tiller number, the two groups had not significant differences. The general instructions, Using MTP-94 as a bridge material to hybrid, is easy to produce offspring of more variation,has easier to selecting of superior traitsand also higher yielding forage maize varieties.6 Analysis the growth dynamic of the two groups materials showed that, in the MTP74 and MTP94 hybrid groups, different materials or different character appeared to different the growth dynamic. Different from the growth of the "slow-fast-slow" cycle of annual maize or annual increase tillering forage maize, most of these materials in plant height and tiller number were "slow-fast-slow-fast-slow" growth pattern, showed the own complex way of growth of the perennial and tillering more materials. Major difference of plant height and tillers in the vegetative growth stage respectively had two times fast growing period and the interaction inhibition between plant height and tillering growth. When the tiller number was increase fast, slow growth of the plant height, vice versa.7 Analysis the phenotype of agronomic characters and fresh,dry production field about the materials of MTP74 hybrid groups and MTP94 hybrid groups in the mowing period showed that P-30 of MTP74 hybrid group and PP-03, PP-10, PP-11, PP-19 of MTP94 group were excellent in character and biological yield, and also showed a strong heterosis. To observing the reproducibility and wintering after mowing, found these materials had strong growth potential, until December after temperature lowered down and growth stop; P-30 and PP-19 overwintering rate were 100%, PP-03, PP-10 and PP-11 overwintering rates were 94.44%,88.89% and 77.78%, respectively. Comprehensive analysis shown that P-30, PP-03, PP-10, PP-11?PP-19 could serve as a series of new type of perennial foragemaize, used in livestock production. |
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