Comparison Of Yield And Quality Traits And QTL Association Analysis Of Yield Traits In 242 Alfalfa Cultivars

242 alfalfa varieties were used to identify the main characteristics of production and quality,based on the yield,quality and combined analysis.Moreover,QTLs related to the main characteristics of yield were analyzed by SSR molecular marker.The results are as fellows.1.Analysis of the main traits of yield of 242 alfalfa varieties242 alfalfa varieties showed the greatly difference among annual output.The yield of the first batch was the highest,as well as the greatest variation coefficient of fresh weight,with the gradually reduce variation coefficient for dry weight,stem diameter,leaf length,plant height,node number of main stem and leaf width.The output of other batches display reduced trend with the increase of cutting times.The correlation analysis showed the significantly positive correlation between dry weight,plant height and fresh weight,as well of plant height and main stem node number,leaf length and leaf width,plant height,main stem node number,leaf width and stem diameter.Moreover,by the partial correlation analysis,the results showed that the fresh and dry weight,plant height,leaf length and main stem node number,leaf length and leaf width,stem diameter were greatly and significantly positive partial correlation,while plant height and leaf width showed the greatly and significantly negative partial correlation.242 alfalfa varieties were divided into 5 groups by NTsys software with the 4.77 Euclidean distance.Comparing to other groups,the average of fresh weight was lowest in group I and the coefficient of variation was highest among 5 groups.The average of dry weight and leaf width were lowest in group II,but the average of leaf length and stem diameter were highest among 5 groups.The yield characteristics of group ? were not significant.The average of plant height and main stem node number were highest in group ?,but the stem diameter was lowest among 5 groups.The average of fresh weight,dry weight,leaf width of was highest in group V,but the main stem node number and leaf length were lowest among 5 groups.The results showed that 13 alfalfa varieties of groups III,IV and V were suitable for growth in the regions of Huaihe River.The main component analysis of yield traits,fresh weight,dry weight,plant heightand main stem node number showed that the contribution rate has achieved 86.78%.2.Analysis of the main quality traits of 242 alfalfa varietiesThe quality of alfalfa was slightly decreased along with the increase of cutting times.The quality traits of the first batch were different among all batches.The variation coefficient of EE was largest,while the index of HC,moisture content,ADF,RPV,NDF,CP were reduce with the cutting time,and the value was 16.10%,15.56%,13.62%,10.13%and 5.40%,respectively.There was a greatly and significantly negative correlation between RFV and EE,ADF and NDF,HC and NDF,while displaying the greatly and significantly positive correlation between NDF and EE,HC and EE,RPV and NDF,HC and ADF,RFV and ADF,RFV and HC.In addition,there was a greatly and significantly partial-correlation between ADF and HC.The results of cluster analysis showed that all varieties were divided into 8 groups by NTsys software with the 1.18 Euclidean distance.The yield characteritics were not significant among group ?,? and ?.The average of ADF and moisture content of group ? were largest,but the HC was lowest among 8 groups.The average EE and NDF of the group ? were largest,but the RFV was lowest among 8 groups.The average HC of group ? were largest,but the CP and ADF were lowest among 8 groups.The average RPV of group ? were largest,but the EE and NDF were lowest among 8 groups.The average CP of group ? was largest,but the moisture content was lowest among 8 groups.The results suggested that 6 alfalfa varieties from groups ?-? were suitable for growth in the regions of Huaihe River.Analysis of the 4 main components of EE,CP,NDF and ADF showed that the contribution rate had achieved 88.28%.3.Combined analysis of yield and quality of 242 alfalfa varietiesThere was a greatly significant positive association correlation between RFV and EE,ADF and NDF,HC and NDF,fresh weight and moisture content,plant height and moisture content,main stem node number and moisture content,dry weight and fresh weight,plant height and fresh weight,main stem node number and plant height,leaf length and plant height,Ieaf length and main stem node number,leaf width and leaf length,stem diameter and leaf length.However,there was a greatly significant negative correlation between HC and EE,RPV and NDF,main stem node number and NDF,HC and ADF,RFV and ADF,RFV and HC,main stem node number and HC,leaf length and HC.Partial correlation analysis suggested that the index of NDF and ADF,NDF and HC,moisture content and fresh weight,fresh weight and dry weight,plant height and main stem node number,main stem node number and leaf length,leaf length and stem diameter displayed greatly significant positive correlation,while the index of ADF and HC,moisture content and dry weight showed the greatly significant negative correlation.The results showed that the EE content of group ? was the largest in all groups.The index of NDF and ADF were lowest in all groups,but the RFV was the largest.The index of CP,NDF,ADF,leaf length and leaf width of group ? were largest,but the HC,RFV,moisture content,fresh weight,dry weight were lowest in all groups.The index of the moisture content,plant height,main stem node number of group ? were largest,but the leaf width and stem thickness were opposite.The index of HC,fresh weight,dry weight in group V were the largest,but the index of EE,main stem node number,leaf length were lowest.4.QTL relevance analysis of main yield traits based on SSR molecular markerThirty-four pairs of SSR primers and 49 QTLs were found to be related to the phenotypes of 6 traits at the p=0.01 level.9 of 49 QTLs were related to Ti(florescence);8 QTLs were related to T2(fresh weight);16 QTLs were related to T3(dry weight);6 QTLs were related to T4(plant height);6 QTLs were related to T5(main stem node number);4 QTLs were related to T6(stem diameter).The variation rate was explained in the range of 0.0058%-192.6899%.SSR primer AW64 interpretation rate of T4(plant height)trait was the largest,following with the primer AW306.The AW 166 interpretation rate of T3(dry weight)trait was lowest.The BI10 and AW332 played a common role in Ti(florescence),T3(dry weight),T5(main stem node number).The AW 166 played a common role in Ti(florescence),T2(fresh weight),T3(dry weight).The AW235 played a common role in T2(fresh weight),T5(main stem node number),T6(stem diameter).The MTIH03,MTIA07(2),AW97,AW146 and BF164 acted on T2(fresh weight)and T3(dry weight).The AW290 acted on T3(dry weight)and T4(plant height).The BF69 acted on T4(plant height)and T5(main stem node number).The 18 pairs of SSR primers were found to be related to the phenotypes of 6 traits at the p=0.001 level.The primer AW 166 has the role on T1(florescence),and MTIH03 contributed on T2(fresh weight),and AW363 acted on T3(dry weight),and AW64 acted on T4(plant height),and BI93 acted on T5(main stem node number),and BE31 acted on T6(stem diameter),which had a maximum interpretation rate.The SSR primer BE92 acted on T1(florescence),and AW235 acted on T2(fresh weight),and AW 166 acted on T3(dry weight),and BI68 acted on T4(plant height),and AW235 acted on Ts(main stem node number),and MTID06 acted on T6(Stem diameter).The primer BI10 was related to T1(florescence)and T3(dry weight),but the primer AW97 was related to T2(fresh weight)and T3(dry weight),which had a minimum interpretation rate.