| Alfalfa occupies a very important position in psture and plaies a key role inpromoting the development of animal husbandry. In order to breeding the newvarieties cultivated in climatic and production conditions similar Northwest oasis inGansu regions, chose the high yield and quality variety of Gannon3#, anti-thripsfast-growing high-yielding varieties of Gannon5#and Fast-growing high-yieldingvarieties of tourists alfalfa, after multiple cross, the growth, yield, quality and otherrelated indicators of36offspring strains and its parents were determined, the degreeof phenotypic differentiation was explored, and used ISSR marker to assist the studyof genetic diversity, understand the offspring hybridization extent, explore the geneticrelationship with the parent, improve the efficiency of selection, and speed up theselection process. The following results were obtained:1.39morphological indicators of the tested materials showed a significant difference(P <0.01). Each indicator has different levels of variability. The largest coefficient ofvariation is leaf to stem ratio of27.89%.The genetic diversity index of every indicatoris large. The tested materials have good polymorphism and rich phenotypic geneticdiversity. The plant height mainly between89~95cm, the growth rate of about1.4cm/d majority, leaf stem than the size set in the range of0.27to0.37, inter nodelength about11cm, the number of branches is16most, the fresh yield rather evenlydistributed, mostly concentrated in the range of26to32t/hm2. The basiccharacteristics of the test material is high plant height, fast growth speed, long internode length, high fresh yield, leaf to stem ratio is moderate, number of branches issmall.2.Cluster all the tested materials of morphological index and nutrition indicators, allthe tested materials divided into three categories, Class A has28offspring lines andthree parent materials, conclude fast-growing1#, fast-growing2#and so on, eachindex showed a moderate level. Class B contains6offspring strains, they arefast-growing4#and fast-growing6#, height is shorter, slower growth rate and loweryields of grass. class C includes only two offspring lines: the fast-growing11#andfast-growing12#, which is characterized by height growth, fast growth, high forage yield, high protein content.3. Combining gray systematic theory, we structured the comprehensive evaluationmodel for all materials. The results showed that fast-growing12#and fast-growing11#were better strains, and the growth height were respectively105.44cm and105.42cm, growth rates were1.75cm and1.68cm every day, meanwhile stem-leafratios were0.30and0.25, branch numbers were23and17, fresh yield were39.99t/hm2and35.13t/hm2, and then crude protein contents were19.95%and23.89%,relative feeding value were153.15%and157.02%. The comprehensive evaluationresult on average growth height, growth rate, leaf-stem ratio, branch number, freshyield, crude protein content,and relative feeding value showed that multi-leaf2#,fast-growing#5, fast-growing20#, and fast-growing21#could be used as goodpotential strains.4.In order to explore the genetic relationship between hybrid progenies of Gannong3#,Gannong5#, tourists and their parents, the genetic diversity was analyzed the by ISSRmarker and4primers were screened to detect the genetic diversity of tested materials.The results showed that:4primers with high polymorphism were screened22informative ISSR markers were generated and showed a polymorphic band ratio of95.45%. The genetic diversity of tested materials was rich. Genetic distances betweenhybrid progenies and three parents were analized, genetic distance betweenfast-growing16#and the three parents was the smallest (0.327), while it between bigleaf1#and the three parents was the biggest (0.752). Clustering results showed that:39materials were clustered into5categories, there were14strains in Categories A,including14fast-growing1#, fast-growing6#and so on;5strains in Categories B,including fast-growing2#, fast-growing3#and so on;13strains in Categories C,including fast-growing4#, fast-growing11#and so on;4strains in Categories D,including fast-growing17#, fast-growing26#and so on; fast-growing18#wasclustered in one category. In accordance with the comprehensive evaluation, thefast-growing11#, fast-growing12#, fast-growing20#and the fast-growing21#areclustered class C, its main features are the high growth height, fast growth speed,high protein content and relative feeding value higher. Multi-leaf2#and fast-growing5#are gathered in groups A, which is characterized by the large numberof branches, fresh yield, high protein content. Selected6lines have good genetic basis,the genetic basis of consistency, adaptability to the environment is also good from thepoint of view of the genetic basis of proven screening lines with a focus on trainingvalue. |
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