| Majia pomelo,as a local characteristic pomelo variety in Jiangxi Province,has superiority economic benefits and development potential,but there are many limiting factors in production,such as single variety structure,lagging exploration and utilization of superiority and new germplasm resources,poor stability of some characters and obvious individual differences.In this study,through field observation in Majia pomelo production area of Qinyuan Village,Guangfeng District,Shangrao City,we found a superiority of Majia pomelo whose flesh color is obviously redder than that of the main strains of the same clone in the garden.By using HPLC and molecular markers,we measured and analyzed the contents of conventional quality,sugar and acid,carotenoids,etc.,in order to evaluate the quality of this superiority and its popularization potential.At the same time,the genetic differences between superioritys and Majia pomelo planted in the same clone in the park were identified,which provided theoretical basis and germplasm materials for identifying and utilizing natural variation materials and enriching variety resources of Majia pomelo.It also includes exploring the supporting cultivation measures to improve fruit quality by covering reflective film on low-lying flat land and cross-pollination treatment,providing technical support and practical basis for high-quality and stable cultivation of Majia pomelo,and promoting the quality improvement and efficiency of Majia pomelo industry,so that Majia pomelo can generate greater economic benefits.The specific results are as follows:1.Comprehensive evaluation and genetic identification of superiority quality.(1)The difference between the superiority(YX)and the current main line of Majia pomelo is mainly reflected in the further deepening of the color of red flesh.The H value of the pulp color of the superiority is 0.685,which is between red(0.523)and orange red(0.785),and the color is described as orange red to red.Lycopene content in YX pulp was as high as 290.34 μg/g,which was significantly higher than that of the control main cultivation of Majia pomelo(MJY-1,MJY-2,MJY-3).At the same time,the content of β-carotene downstream of lycopene metabolism in YX pulp is lower than that of the control group.In terms of conventional fruit quality,the YX peel thickness is25.85 mm,which is generally lower than that of the main strains in the park.The contents of YX soluble sugar and organic acids were not significantly different from those of the control group.(2)The genetic polymorphism analysis of 7 groups of samples from YX and the same clone(MJY-1～MJY-6)in the same park was carried out by 12 pairs of SSR primers.The results showed that 54 bands were amplified in 7groups of samples,with 46 polymorphic bands,and the polymorphism ratio was 85.19%.On average,each pair of primers amplified 4.5 alleles and 3.8polymorphic bands.Among them,there are three pairs of primers,TAA1,CMS7 and CMS24,which can effectively identify the genetic differences between superioritys and main lines.This study preliminarily speculated that the superiority originated from the plant variation of the mutant scion after asexual reproduction.2.The effects of covering reflective film and cross-pollination on fruit quality.(1)The adult fruit trees of Majia pomelo planted in low-lying flat land were covered with reflective film for the first time(F1)in the current year’s color change period(150 DAF),and then different adult fruit trees of Majia pomelo with the same tree vigor were covered with film again every 15 days(the following two treatments are referred to as F2 and F3 for short).The control group was Majia pomelo(CK)in the same environment without any treatment,and both the experimental group and the control group were the best in Majia pomelo.The results showed that F1、F2 and F3 all reduced the peel thickness and increased the juice yield to a certain extent compared with CK,among which F2 was the most significant result.In terms of internal quality,F1、F2 and F3 all increased the soluble solids(TSS),solid-acid ratio and vitamin C(Vc)content of fruits,and the improvement effect was positively correlated with the duration of film mulching.The content of titratable acid(TA)in coated pulp was negatively correlated with the duration of coating.(2)The treatment with reflective film had no significant effect on the content of fructose and glucose in fruits,mainly reflected in the change of sucrose content in fruits.F3 significantly increased the sucrose content in pulp compared with CK,and had the best effect on the total soluble sugar in fruit.The organic acid content of fruits treated with film mulching decreased with the extension of film mulching duration.The average content of organic acids in F1 is 3.84 mg/g,which is 15.6% lower than CK.As for bitter substances,F1、F2and F3 had no significant effect on naringin content,but F1 and F2 significantly reduced the content of limonin in pulp,while F3 significantly increased the content of limonin in pulp.The stress response hormone abscisic acid(ABA)was measured,and it was found that the ABA content in pulp increased with the extension of the duration of film mulching.(3)The results of cross pollination with two local pomelo pollens T1 and T2 as male parents and Majia pomelo as female parents are as follows:Compared with CK fruits,T1 and T2 increased by 47.6% and 35.2%respectively in single fruit weight;The edible rate increased by 19.5% and23.9% respectively.T1 and T2 significantly reduced the peel thickness by16.6% and 27.0%.However,cross-pollination treatment reduced the fruit juice yield and made seedless fruits produce a certain number of seeds.Intrinsically,cross-pollination treatment had no significant effect on TSS content of fruit,but effectively reduced the TA content of fruit,and then significantly increased the solid-acid ratio and Vc content.(4)T1 and T2 both increased the soluble sugar content of Majia pomelo fruit to some extent,among which T2 increased the soluble sugar components and total sugar content most significantly.Compared with CK,T1 and T2 have no obvious change in organic acid content.Cross-pollination treatment can significantly reduce the content of naringin in pulp.Compared with CK,the content of naringin in T1 and T2 decreased by 32.9% and 32.5% respectively.But T2 significantly increased the limonin content in pulp compared with CK. |
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