The Availability Of F₂ Populations Of Interspecific Hybrids In Agropyron Gaertn.

The genus of Agropyron Gaertn.has been using as a valuable wheat tertiary gene pool for the wheat improvement,and playing an important role in the forage production.In order to provide a basis for the identification and utilization of the Agropyron germplasm,the study evaluated F₂ generations of interspecific hybrid from two typical diploid A.mongolicum Keng and A.cristatum L.through agronomic characters and cytology.The research results as follow.1.Eleven agronomic traits of 87 materials of the F₂ generation of the Agropyron interspecific hybrids were analyzed.Eighty-seven materials showed obvious genetic variation（18.46%–83.32%）in all agronomic traits,and the variation of spikelet number was the largest.The diversity index Shannon value of 87 materials showed eighteen materials detected higher diversity index（H=2.43–2.54）and two materials had lower diversity index（H=1.96–1.99）.The ear width diversity index showed the highest（H=5.55）.The correlation and gray correlation analysis found that the ear length and plant height were important factors affecting the number of florets per spikelet（ri=0.91,ri=0.90）.The factor analysis found that the four principal components,spike length,spike width,number of spikelets per spike and number of florets per spike,had obvious variations.The study materials were divided into four groups at the Euclidean distance of 6.5.The third type of Agropyron materials had the characteristics of high stalks and multiple tillers,which could be used to breed high-quality forage grass.The fourth type of Agropyron materials had many fine traits such as multiple flowers and multiple spikes could be excellent germplasm resources for the wheat genetics and breeding.Through dynamic analysis found plant height and tiller were complementary to each other during plant growth and development.From the jointing stage to the mature stage,plant height and number of tillers had been increasing.According to the field performance,the F₁ generation seeds was mixed as one group according to the relatively neat and consistent of Agropyron F₂generation.The eight groups selected through the recurrent selection by the analysis of their plant height,tiller,panicle type and growth period as new varieties for the forage grass breeding.2.The karyotypes of two typical diploid A.mongolicum Keng and A.cristatum L.,and their interspecific hybrid F₂ were conducted.The results showed that all of the five study materials were diploid with chromosome number of 14.The formula of chromosome types was as followed.The male A.cristatum Z1842 was2n=2x=10m+4sm;the female A.mongolicum Z2098,2n=2x=8m+6sm;the hybrid F₂-19,2n=2x=14m;the F₂-69,2n=2x=14sm;and the F₂-94,2n=2x=6m+8sm.The nuclear asymmetry coefficients of Z1842,Z2098 and F₂-19 were 61.70%,62.10%and 59.27%,respectively,all of which were"1A"type.The nuclear asymmetry coefficients of F₂-69 and F₂-94 were 64.90%and 64.51%respectively,all of which were"2A"type.The research found the two typical diploid species A.cristatum and A.mongolicum and their interspecific hybrid progeny materials had the similar chromosomes,and the karyotypes of all of them were basic symmetrical types.However,the chromosome composition of Agropyron spp.showed rich diversity.The research provides some theoretical and materials basis for the genetic diversity and phylogenetic evolution of Agropyron Gaertn.,and also for the improvement of Agropyron forage,wheat and some related plants.