| Pakchoi(Brassica campestris l.ssp.chinensis var.communis),also known as non-heading Chinese cabbage,common Chinese cabbage,Chinese cabbage and rape,is widely cultivated in the Yangtze River Basin of China.It is a one-or two-year-old herbaceous plant with green leaves as its products.Pakchoi texture fresh and tender,rich in nutrition,is one of the green leafy vegetables loved.There are so great differences in climatic conditions between regions of China that many local varieties.There are a lot of high-quality varieties of pakchoi to be found and improved.This experiment was based on 82 pakchoi germplasm resources,the plant height,plant width,leaf length,leaf width and other phenotypic traits,as well as quality traits such as glucosinolates,VC,protein and soluble sugars,were analyzed during vegetative growth period.The results provided a basis for selecting fine pakchoi germplasm and further using it as breeding parent material.The main results of this study are as follows:(1)the phenotypic traits of pakchoi in seedling stage had little difference,the coefficient of variation was between 22.11% and 38.0%.The variation of phenotypic traits in mature period is abundant,the variation coefficient ranged from 5.56% to 116.55%,in which the largest variation coefficient was leaf spines(116.55%),followed by leaf surface vesicular(62.08%)and leaf edge undulation(61.49%),the coefficient of variation(CV)of these characters was more than 50%,which shows that the variation range is large and there is more possibility in breeding.The phenotypic characters with smaller CV were waistband(5.56%),petiole thickness(18.91%),SPAD value(19.38%)and leaf apex shape(19.67%),after long-term natural selection and artificial selection,these characters have formed stable phenotypic characteristics respectively.The SPAD values of the tested materials ranged from19 to 60,with a maximum of 57.8 and a minimum of 19.067,and the maximum of 3.031 times the minimum,indicating a significant difference,with the SPAD values of BOB19-20 being the largest,followed by BOB19-17,Bob19-50 and BOB19-08.(2)Based on the cluster analysis of phenotypic characters of pakchoi,82 resources were divided into 3 groups,among which Group I had larger plants,wider leaves and the most robust growth,Group II had shorter plants and rounder leaves,the leaves of Group III were more shriveled and rolled,and the leaves were more flower-leaf type,with a certain degree of girdle.Based on the correlation analysis of phenotypic traits of pakchoi,it was found that plant width,leaf width,leaf length and SPAD value were positively correlated with plant height,while leaf color and leaf shape were negatively correlated with plant height,and leaf color,leaf shape and plant width were also significantly negative correlation;plant width,leaf length(the largest leaf),leaf width(the largest leaf)were significantly positive correlation between the three,reflecting that the bigger the plant,the stronger the growth of pakchoi,which is more suitable for the climate conditions in Hunan province.(3)The kinds and contents of glucosinolates in 82 pakchoi germplasm resources were analyzed,and 8 glucosinolates were detected,4 of which were Indole glucosinolate,4ME,4OH,GBC and NEO,the contents ranged from 0.462 μmol/g to 10.352 μmol/g;Three aliphatic glucosinolates,GER,IBE and RAA,were found in the range of 0.14-5.436μmol/g,and there is also an unknown glucosinolate found in the range of0-10.269μmol/g.BOB19-34(5.436μmol/g),BOB19-20(5.041μmol/g),BOB19-100(4.723μmol/g),BOB19-90(4.68μmol/g)and BOB19-52(4.189μmol/g)were the five pakchoi cultivars with high content of Aliphatic glucosinolate.BOB19-87(10.352 μmol/g),BOB19-91(6.549μmol/g),BOB19-52(6.121μmol/g),BOB19-67(6.086μmol/g)and BOB19-90(6.035μmol/g)were with high content of Indole glucosinolate.BOB19-34(21.55μmol/g),BOB19-87(14.089μmol/g),BOB19-90(13.054μmol/g),BOB19-67(13.036μmol/g)and BOB19-20(12.754μmol/g)were foundwith the highest total glucosinolate content.(4)according to the cluster analysis of glucosinolate content in pakchoi,it can be divided into three categories.Group I contained 35 pakchoi materials,the total glucosinolates content of pakchoi ranged from 6.126 μmol/g to 13.054 μmol/g which ranked second among the three pakchoi taxa,the indole group glucosinolates content ranged from1.554 μmol/g to 6.549 μmol/g,the content of aliphatic glucosinolates varied from 0.516μmol/g to 5.041 μmol/g;The Group II contained 35 pakchoi materials,and the content of glucosinolates is the lowest of the three groups.The content of total glucosinolates ranged from 2.190 μmol/g to 6.444 μmol/g,the content of indole glucosinolates ranged from 0.462μmol/g to 3.82 μmol/g,and the content of aliphatic glucosinolates ranged from 0.14 μmol/g to 1.594 μmol/g.There were only 2 materials in Group III(BOB19-34 and BOB19-87),of which the total glucosinolates content of BOB19-34 was 21.55 μmol/g,the content of aliphatic group was 5.436 μmol/g,indole group 4.845 μmol/g,BOB19-8714.089 μmol/g,aliphatic group 2.399 μmol/g,indole group was 4.845 μmol/g.Group III Pakchoi with the least number of resources,but the highest glucosinolate content,belongs to high glucosinolate pakchoi group.(5)The correlation analysis of phenotypic traits and glucosinolates content in pakchoi showed that SPAD value was significantly correlated with IBE,4OH,GER,GBC,4ME and NEO,the results showed that the stronger the growth of pakchoi,the richer the nutrient components and the better the quality.Based on the analysis of phenotypic characters and glucosinolate content of pakchoi,The better resource of pakchoi was preliminary selected as BOB19-34,BOB19-90,BOB19-67,BOB19-20,BOB19-52,BOB19-35,BOB19-91 and so on.(6)The variation of conventional quality(vitamin C,protein,soluble sugar,etc.)of pakchoi germplasm resources was tested and analyzed.The results showed that there was a significant difference in the content of VC among the tested materials.The materials with high vitamin C content were BOB19-91,BOB19-90,BOB19-88,BOB19-78 and BOB19-74,etc.,BOB19-91(3513.108 mg/100g),which had the highest VC content,had significant difference with other pakchoi,BOB19-90 and BOB19-88 had no significant difference,and BOB19-88 and BOB19-78 had no significant difference.The protein content of the tested materials varied greatly,ranging from 0.443 mg/g to 33.056 mg/g,the highest was BOB19-67(33.056 mg/g),the next were BOB19-62(32.099 mg/g),BOB19-44(24.446mg/g),BOB19-66(22.897 mg/g),BOB19-100(22.746 mg/g)and so on.Compared with VC and protein,the difference of soluble sugar content was small,the range was 1.301mg/g-4.845 mg/g,the highest was BOB19-38,the next were BOB19-90,BOB19-44,BOB19-33,BOB19-58.After comparing the average membership function of cabbage quality,found that the BOB19-62(VC 198.31 mg/100 g,protein 32.099 mg/g,soluble sugar3.104 mg/g)was the best material,and BOB19-38,BOB19-90,BOB19-67 and BOB19-44 were the next,its comprehensive quality characters were also superior. |
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