| Jinqiu shatangju tangerine,a new early mature hybrid citrus variety with independent intellectual property rights,has high sugar and low acid contents,high yield,tender residue and canker resistance characteristics.Since the variety was released in 2012,it has been widely planted in citrus producing areas in China.Because of the difference in climate in citrus producing areas in China,the quality of Jinqiu shatangju tangerine varies greatly in different climate regions.At present,there is no systematic comparative study on the quality of Jinqiu shatangju tangerine in different climate regions,which is not conducive to its production and promotion.Therefore,from2019 to 2021,the fruit quality of 4～7 years old Jinqiu shatangju tangerine was studied at 120 orchards in 103 counties located in five climate types: south subtropics,middle subtropics,north subtropics,dry-hot valleys,and high-humidity together with low sunshine hour area,in order to provide reference for suitable cultivation environment selection of this tangerine variety.1.Climatic profiles of different climatic regions in this studyIn this study,30 years’ meteorological data of five sampling climate regions were collected.The southern subtropics region mainly refers to southern Guangxi and Guangdong(except northern Guangdong).The average annual temperature in this region was 20.56～22.58 ℃,sunshine duration was 1488.28～1933.81 h,rainfall was 1274.22～1990.64 mm,and Relative humidity76.02%～80.57%.The middle subtropics include central and south Jiangxi,central and south Hunan,northern Guangxi and northern Guangdong.The average annual temperature in this region was16.93～22.34 ℃,sunshine duration was 1317.00～1784.17 h,rainfall was 1057.70～1900.91 mm,and relative humidity was 71.33%～80.10%.The northern subtropics include Hanzhong Shanxi,Hubei,Zhejiang and northern Hunan,in which the annual average temperature was 15.15～18.03 ℃,sunshine duration was 1069.86～1900.36 h,rainfall was 804.19～1773.06 mm,and relative humidity was 75.15%～79.68%.The dry-heat valleys area include the dry-hot valley zone of Yuanjiang river in Yunnan province and Jinshajiang River in Yunnan and Sichuan Province,in which the annual average temperature was 15.54～21.13 ℃,annual sunshine hours was 2018.54～2499.10 h,annual rainfall was 780.06～1126.10 mm,and relative humidity was 66.92%～76.23%.The high-humidity together with low sunshine hour area mainly include most citrus producing areas in Sichuan basin and Chongqing,in which the annual average temperature was 16.24～18.74 ℃,the annual sunshine hours was 876.55～1271.56 h,the annual rainfall was 902.64～1240.38 mm,and the average relative humidity was 77.04%～81.90%(except for Cangxi county and Jiange county).2.Fruit quality of Jinqiu Shatangju tangerine in different climate regionsThe flowering and fruit ripening time of Jinqiu Shatangju tangerine in different climatic regions were different.The flowering time in southern subtropics and dry-hot valleys was mainly from early February to early March,and fruit ripening time was from early September to early October.The flowering time in middle subtropics was concentrated in late March to mid-April,and fruit ripening time was late October to early November.The flowering time of high humidity together with low sunshine hour region and northern subtropics was concentrated in late March to mid-April,and the fruit ripening time was mid-November to early December.The fruit quality of Jinqiu Shatangju tangerine differed considerably in different climate regions.The results of three consecutive years showed that the single fruit weight was26.42～108.51 g in different climate regions.Among them,the southern subtropics was66.73～77.38 g,the middle subtropics was 56.28～70.23 g,the northern subtropics was 42.82～72.51 g,and the dry-hot valleys was 73.22～82.55 g.The a* values of fruit redness ranged from10.26～31.69,among them the southern subtropics was 20.98-30.65,the middle subtropics was28.10-30.02,the northern subtropics was 28.63～31.69,the dry-hot valleys was 10.26～25.16 and the high humidity together with low sunshine hour region was 24.79～29.57.The b* values of fruit yellowness ranged from 64.91～73.18,among them the south subtropics was 64.54～65.85,the middle subtropics was 64.65～65.95,the northern subtropics was 64.69～65.23,the dry-hot valleys was 66.69～73.18,and the high humidity together with low sunshine hour region was 64.55～66.71.The fruit edible rate ranged 74.82%～80.17%,among them the southern subtropics was75.84%-80.17%,the middle subtropics was 75.82%～77.57%,the northern subtropics as77.73%-78.71%,the dry-hot valleys was 7 4.82%～75.88%,and the high humidity together with low sunshine hour region was 77.81～79.28%.The content of fruit soluble solid(TSS)ranged from10.38% to 15.53%,among them the southern subtropics was 10.58%～12.88%,the middle subtropics was 12.02%～14.30%,the northern subtropics was 12.56%～15.53%,and the dry-hot valleys was 10.43%～11.84%,the high humidity together with low sunshine hour region was10.38%～11.69%.The fruit titratable acid(TA)content was 0.28%～0.59%,among them the southern subtropics was 0.26%～0.33%,the middle subtropics was 0.32%～0.46%,the northern subtropics was 0.36%～0.59%,the dry-hot valleys was 0.29%～0.42%,and the high humidity together with low sunshine hour region was 0.28%～0.37%.The content of fruit vitamin C(Vc)ranged from 28.52～42.26 mg/(100m L),among them the southern subtropics was 30.75-37.50mg/100 m L,the middle subtropics was 33.11～41.08 mg/100 ml,the northern subtropics was34.19-44.26 mg/100 ml,the dry-hot valleys was 28.50～30.02 mg/100 ml,and the high humidity together with low sunshine hour region was 28.86～34.04 mg/100 ml.The average yield per plant was 16.67-37.14 kg/plant(4～7year old tree),among them the highest yield was observed in the northern subtropics and high humidity together with low sunshine hour region,the lowest yield occurred in dry-hot valleys.Fruit type was the largest and ripened earliest in the south subtropics and dry-hot valleys,followed by the high humidity together with low sunshine hour region and the middle subtropics,and the fruit from the northern subtropics had the smallest fruit type and ripened at the lastest.Fruits from the northern subtropics and the middle subtropis were the reddest,followed by the high humidity together with low sunshine hour region,while the dry hot valleys and the southern subtropics were more yellow and high brightness.The contents of fruit total soluble solids(TSS)and titratable acid(TA)were the highest in the middle subtropics and northern subtropics,while the lowest in the dry-hot valleys.The contents of fruit vitamin C(Vc)in high humidity together with low sunshine hour region and dry hot valleys were lower than that in other regions.In the sensory evaluation,the satisfaction degree of fruits from the middle subtropics and the north subtropics were the highest,and in the two regions the sensory evaluation of excellent or good reached more than 80% in 2019 and more than 70% in 2020.3.Composition of sugar and acid components in different quality of fruitsThe main sugar in Jinqiu shatangju tangerine fruit was sucrose,glucose and fructose,followed by galactose and inositol.Among them,the content of sucrose was 33.04～77.30 mg/ml,fructose was 23.41～48.47 mg/m L,glucose was 17.42～33.79 mg/ml,galactose was 3.51～6.38 mg/ml,inositol was 2.07～6.91 mg/ml.The contents of sucrose,fructose and glucose in excellent fruits were significantly higher than those in poor fruits,and the contents of sucrose and fructose in most excellent fruits were significantly higher than those in medium fruits.The main organic acids in fruit were citric acid and malic acid,follow by quininic acid,oxalic acid and γ-aminobutyric acid(γ-GABA),and their contents were 0.65～3.64 mg/ml,0.95～2.48mg/ml,0.11～0.34 mg/ml,0.22～0.77 mg/ml and 0.05～0.27 mg/ml,respectively.Due to Jinqiu Shatngju tangerine was a variety with insufficient acid content,the increase of acidity is beneficial to improve its flavor and quality.Excellent fruit had the highest content of citric acid and malic acid and good flavor,followed by medium fruits,and poor fruits had low acidity and poor taste.The content of γ-aminobutyric acid in excellent fruit was the highest,which has health care value.4.Relationship between meteorological factors and fruit qualityPrincipal component analysis and comprehensive score calculation were used to analyze and compare the comprehensive fruit quality of Jinqiu shatangju tangerine in different climate regions.Topsis codirection and dimension reduction were performed on the data,and then five principal components were extracted from 2019 to 2021.Their eigenvalues in 2019 were 4.525,3.057,1.371 and 1.077 with the cumulative contribution rate of 75.308%.In 2020,the eigenvalues were 4.567,2.703,2.471,1.676 and 1.434 with the cumulative contribution rate was 75.595%.In 2021,the eigenvalues were 4.888、2.953、2.571、1.588 and 1.059 with the cumulative contribution rate was76.814%.The results showed that the fruit quality in northern subtropics and middle subtropics was the best,that in southern subtropics and high humidity together with low sunshine hour area were good,and that in dry-hot valleys was poor.The main reason was that the typhoon rainfall in the south subtropics had not ended,and the dry-hot valleys were still in the rainy season during fruit harvest season.Jinqiu shatangju tangerine fruit quality was influenced by many meteorological factors,mainly including annual sunshine hours,annual available accumulated temperature above 10℃,July-August average temperature,and the weather meteorological parameters of one month before harvest(including average temperature,day-night temperature difference,relative humidity,sunshine hours and rainfall).These meteorological indexes mentioned above can be used as an important index for the location selection of high-quality Jinqiu shatangju tangerine planting.5.ConclusionThe ripening period of Jinqiu shatangju tangerine was the earliest in the south subtropics and dry-hot valleys,followed by the middle subtropics and the Sichuan-Chongqing high-humidity together with low sunshine hour area,and the last in the north subtropics.The fruit pericarp and flesh were red in the middle subtropics,north subtropics and high-humidity together with low sunshine hour area,but yellow in the middle subtropics and dry-hot valleys.The fruit type was the largest in the south subtropics and dry-hot valleys,and smaller in the north subtropics and the middle subtropics.Fruit TSS content was the highest in the middle and north subtropics,and the lowest in dry-hot valleys.Fruit TA content was the highest in north subtropics and the lowest in dry-hot valleys.In terms of quality,the most suitable planting areas for Jinqiu shatangju tangerine are the middle and north subtropics,and high-humidity together with low sunshine hour area is suitable area,and the south subtropics and the dry-hot valleys are the sub-suitable planting areas.But the fruit of Jinqiu shatangju tangerine planted in the south subtropics and dry hot valleys can be harvested around the National Day,in which low acid and high sugar citrus fruit is lack in market. |
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