| Sweetpotato[Ipomoea batatas(L.)Lam.]is an important crop for food,feed,and industrial raw materials.Starch is the major chemical component in sweetpotato storage roots except water,so starch content,yield and quality have always been important research contents of sweetpotato breeding and cultivation.With the continuous in-depth research and popularization of the value of nutrition and health care sweetpotato storage roots,the consumption of healthy sweetpotato storage roots is increasing year by year.In this paper,the author took 83 materials mainly from the sweetpotato breeding process of our research group as the research object.Based on the classification of the varieties population by the color values of the storage roots flesh color and by the dry matter content in storage roots,the divergence and correlations between the dry matter content,starch content,amylose ration in starch,amylose content in fresh root,and starch granule size and its span were analyzed in different varieties,different varieties populations and different planting locations.The changes of the taste indexes of storage root after cooking in different varieties and in different populations,and their correlations with the dry matter content,starch quality,were also analyzed.Changes in starch quality of 6 varieties with different starch content and taste qualities during storage root cooking were studied.Using subordinate function values analysis and principal component analysis of the starch quality and edible taste qualities in 83 test sweetpotao materials,some breeding lines and germplasm resources with excellent starch quality and taste were screened out in present paper.The main results are as follows:1.The determination results of the color value 5 parameters,L,a*,b*,C,and h~0of flesh storage root,and the analysis of variance showed that the differences between the varieties were extremely significant.The cluster analysis by color values divided 83varieties into 6 populations and 11 subpopulations(FC groups):white flesh-color,light yellow flesh-color,yellow flesh-color,orange flesh-color,red flesh-color,and purple flesh-color.Among those populations without purple flesh-color varieties,from the FC1population(white flesh-color)to the FC8 population(red flesh-color),the color values L and h~0gradually decreased,and a*,b*and C gradually increased.L and h~0was extremely significantly positive correlated;L and a*,b*,C were extremely significant negative correlations.There were extremely significant positive positive correlation between a*,b*,C.In the three purple fleshed sweetpotato varieties populations,a*had a extremely significant positive correlation with C,and b*had a extremely significant positive correlation with h~0.2.The dry matter content in storage roots had extremely significant differences between varieties,those varieties without purple-flesh would be divided into 7 dry matter content varieties populations(DM population).Although 7 DM populations were distributed in all kinds of flesh color populations,but varieties of DM population with high dry matter content were more in the white(FC1 and FC2)and light yellow(FC3),and varieties of DM groups with low dry matter content were more in the red flesh-color populations(FC7 and FC8).The dry matter content in non-purple flesh sweetpotato storage root had a extremely significant positive correlation with the color values L and h°,and a extremely significant negative correlation or a significant negative correlation with a*,b*,and C.3.Starch quality were extremely different between different varieties and different populations.The distribution of starch content in various FC populations was similar to dry matter content in various FC populations.The ratio of amylose in starch is insignificantly different among the 11 flesh-colored groups;the amylose contents in fresh storage roots of the white,light yellow,and yellow flesh-colored populations were significantly higher than those in the orange and red populations;There was no significant difference in the granule size of the 11 FC populations.The white population FC1 had the largest granule size,and the orange population FC5 had the smallest granule size;the red and orange group had larger granule size spans.Among FC populations,the content and granule size of starch and amylose content were extremely significantly positively correlated with dry matter content,L and h~0,and extremely significantly negatively correlated with a*,b*,and C;amylose ratio were extremely significantly positively correlated with a*,b*,C,and extremely significantly negatively correlated with L,h~0,dry matter content,and starch content;the starch granule size span were extremely significantly positively correlated with a*,b*,C and the amylose ratio,and were extremely significantly negatively correlated with L,h~0,dry matter content,starch content,and amylose content,and significantly negatively correlated with the granule size.Among DM populations,the contents of starch and amylose were significantly or extremely significantly positively correlated with dry matter content,L and h~0,and significantly or extremely significantly negatively correlated with a*,b*,and C;the ratio of amylose were significantly positive correlated with a*,b*and C,were significantly or extremely negative correlated with dry matter content,starch content,amylose content,L and h~0;Starch granule size were significantly positively correlated with dry matter content,starch content,and amylose content,and was significantly negatively correlated with amylose ratio;granule size span were significantly or extremely significantly positive correlated with a*,b*,and C,and were significantly negative correlated with dry matter content,starch content,amylose content,granule size,L and h~0.The subordinate function values analysis and principal component analysis screened out 10 new starch-type lines and germplasm resources with different starch quality characteristics.4.AMMI model analysis showed that the dry matter content and starch quality had significant differences among varieties,locations,and varieties×locations.Different locations had different abilities to evaluating starch quality traits of starch-type,edible-type and purple sweetpotato varieties.The Hechuan site(LHI)was the most suitable for identifying the amylose content of purple fleshed varieties;the Yongchuan site(LY2)was the most suitable for identifying the starch content of purple fleshed varieties;the Pengshui site(LP3)was suitable for the dry matter content of the three types of varieties,starch content of starch-type varieties,amylose ratio and content,and starch granule size span,starch granule size of edible-type and purple fleshed varieties;Wanzhou location(LW4)was suitable for starch granule size of starch-type varieties and the starch content,the amylose ratio and content,the granule size of edible-type,and the amylose ratio of purple fleshed varieties.5.There were significant differences in various edible taste indexes between varieties and populations.The comprehensive score index of edible taste were significantly positive correlated with the flesh-color score,aroma,sweetness,viscosity,silty,and fiber,and significantly negatively correlated with the moisture.The edible taste were mainly significantly or extremely negatively correlated with dry matter content,starch content,and amylose content,but had a small correlation with amylose ratio,starch granule size,and granule size span.Subordinate function values analysis and principal component analysis showed that sweetness,viscosity,aroma,and dry matter content(positively correlated with starch content)were the key factors affecting the edible taste.Subordinate function values analysis and principal component analysis screened out 29,34,59,61,63,29,34,59,61,63 and other edible new varieties and germplasm resources with excellent taste,and these varieties were distributed among the FC3-FC7 and the DM3-DM5,and their dry matter content were between22.00-33.00%,starch content between 10.00-18.00%,amylose content between2.60-4.20%,granule size between 20.00-25.00μm.6.The changes during the cooking process of the storage root of 6 representative varieties showed that the varieties with a high comprehensive score of edible taste had higher amylase activity than the low score,and the amylase activity showed a gradual decline,while those with a high comprehensive score of cooked storage root.Compared with the 3 varieties with lower edible scores,the starch content of 3 varieties with higher scores changed more before and after cooking.The soluble sugar content showed a gradual upward trend during the cooking process,and the higher-scoring varieties had higher soluble sugars after cooking than the lower-scoring varieties.Conclusion:There were significant differences in starch qualities among different varieties and varieties population.According to the analysis results of the AMMI model,suitable planting locations for different use of varieties can be obtained.There were significant differences in the taste quality of cooked storage root between varieties and populations with different flesh color and different dry matter content.Fresh storage root with high amylase activity,large increase in soluble sugar after cooking,and large changes in starch content before and after cooking have better taste.Among the FC3-FC7 populations with light yellow to orange flesh-color,and the DM3-DM5populations with dry matter content between 22.00-33.00%and starch content between10.00-18.00%,good sweetpotato variety would be easy to screen out with better taste,their fresh storage roots amylose content was between 2.60-4.20%and the granule size is between 22.00-24.00μm.In this paper,10 starch-type lines and 11 edible-type lines were screened out,those would be continue to be identified in further breeding process and be used as excellent germplasm resources in future starch-type and edible quality improving breeding. |
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