Study On The Main Characters Of Hybridization Descendants Between Mengnong Qingsi No. 1, 2, 3 And Jaboo Pacetter

In order to breed new forage crop cutivars (new germplasms) of good characters combining with their parents, three interspecific hybrids were obtained via crossing between Mengnong Qingsi No.1, 2, 3 and Jaboo pacetter, and F2 were obtained via planting and selecting in filed. The main agronomic characters, chromosome configuration, proxidase isozyme zymograms phenotype and RAPD of hybrids F1 and their F2 were analyzed and compared, which would provide theory bases for selecting and using of the hybrid descendants. The results as follows:1. The three hybrids F1 of Mengnong Qingsi No.1×Jaboo, Mengnong Qingsi No.2×Jaboo and Mengnong Qingsi No.3×Jaboo were the medium-later mature varieties respect- tively, and the growth periods were 138d to146d. The plants thrived, and their heights were 393cm to 413cm, which was increased by 80cm to 100cm than their male parents, and was increased by 11cm to 21cm than their female parents. The tillering number per plant were 5.5 to 7.3, the stem-leaves rates were 3.05 to 3.07, the pollen sterility rates were above 91.90%, the natural seed set rates were 83.21% to 93.93%. The yield of fresh grass was increased by 13.40%to 15.26%than their male parents, but which was similar to their female parents. The yield of seeds was increased by 3.87% to 9.09% than their female parents, but which were inferior to their male parents.2. Three hybrids F2 thrived, the tillering number per plant, the pollen sterility rates, heights, the yield of fresh grass and seeds declined a little than hybrids F1 respectively. The stem-leaves rates were similar to hybrids F1. The spike types were similar to their female parents, similar to their male parents, and in the middle of their parents. The characters of spike type could be used as morphology basis for selecting excellent strains in cross generation.3. The content of cyanide in fresh stems and leaves of hybrids F1 were very low from 8.38mg/kg to 10.94mg/kg when the plant height was above 140 cm. The Brix of hybrids F1 and F2 was higher by 8.7% to 11.9% and 8.4% to 8.9% respectively.4. The chromosome pairing in pollen mother cells at metaphaseⅠ(PMCMⅠ) was regular, the chromosome configurations was 2n=2x=20(10Ⅱ), but the frequency rod bivalent was higher than that of their parents. The synaptonemal complexes were flabbily, the genetic composing of their parents had some difference. 5. The proxidase isozyme (POD) zynograms phenotype of all cross combinations F1 at heading stage and separated spike type of hybrids F2 could be used as genetic markers in protein level for selecting excellent strains in cross generation.6. The 163 loci of RAPD markers with 9 fit primers to tested plants were amplified, and the percentage of polymorphism polymorphic loci was 71.78%; the genetic distances were 0.3469, 0.4872, 0.3913 between their parents, such as Mengnong Qingsi No. 1,2,3 and Jaboo respectively; the genetic distances were 0.4000, 0.5102, 0.5396 between hybrids F1 and their female parents respectively; the genetic distances were 0.3953, 0.5455, 0.5238 between hybrids F1and their male parents respectively.