Evaluation of nutrients and related environmental factors for wolfberry (LyciumbarbarumL.) fruitsproduced from indifferent areas of China
Wang Yajun1, 2，Liang Xiaojie2，Guo Sujuan1*，Li Yuekun2，Zhang Bo2，Yin Yue2，An Wei2，Cao Youlong2， Zhao Jianhua2 (1. Key laboratory for Silviculture and Conservation,Ministry of Education, Beijing Forestry University, Beijing 100083, China; 2. National Wolfberry Engineering Research Center, Yinchuan 750002, China) *Corresponding author: Sujuan Guo,Ph.D.,E-mail address: [email protected] Abstract: Wolfberry fruit can be Chinese herbal medicine or food, but the fruit quality and the levels of functional components in wolfberries grown in different producing areas are different. In this study, we collected wolfberry fruit samples from 67 gardens distributed in seven wolfberry producing areas in China (Yinchuan and Zhongning in Ningxia, Jingyuan in Gansu, Nuomuhong in Qinghai,Hangjinhouqi and Wulateqianqi in Inner Mongolia, and Jinghe in Xinjiang) to investigated their internal nutrition ingredients and related environmental factors. The wolfberry fruits from seven different areas showed greatly difference in nutritional ingredients, and each of them had special characteristics. Correlation analysis revealed that the internal nutrient ingredients were highly related to each other.Based on the analysis ofratio of total sugar to betaine (sugar-alkali ratio), we created five categoriesof wolfberry quality: high betaine low sugar (sugar-alkali ratio≤15.1), high betaine medium sugar (15
Keywords:Wolfberry(Lyciumbarbarum L.); Nutrition ingredients; Production area; Quality evaluation
Introduction Lyciumbarbarum L. (Solanaceae), a perennial, deciduous shrub (Cao & He, 2013), is commonly known as wolfberry or wolfberry fruit (Bondia-Pons et al. 2014) and is the main economic tree in the northwest arid area of China. Wolfberryfruit has many pharmacological effects, such as enhancing immunity, anti-aging, anti-tumorigenesis, and anti-oxidative (Chang & So, 2008; Lin et al., 2008; Zheng & Hu, 2008; Ma et al., 2009). Modern medical studieshave foundthat wolfberry fruit contains several function ingredients,Lyciumbarbarum polysaccharide (LBP), medlar total saccharide, betaine, carotenoids, flavonoids, and pharmacodynamic amino acids (Qian et al., 2004; Liu et al., 2008; Dong et al., 2009; Liu et al., 2014). Wolfberry fruit is also rich in sugar and organic acids (Xie et al., 2001; Zhang et al., 2016). Among these ingredients, LBP is considered as the most important ingredients determining pharmacological effects of
1 wolfberry fruit, followed by betaine and flavonoids. Generally, the nutrients in wolfberry fruitmainly include twosubstances with opposite characteristics: total sugar representsacidic substances and betaine representsalkaline substances. The contents of these two substances and their equilibrium ultimately determines the quality of wolfberry fruit (Gao and Li, 2003; Zhang et al., 2008). And the wolfberry with a balanced ratio of total sugar to betaine (sugar-alkali ratio) is of high quality. In China, the main cultivated wolfberry variety is ‘Ningqi 1’, a species of L.barbarumL., which has the largest planting area through the country and accounts for more than 80% of the total cultivation. As the geo-authentic habitat of wolfberry, Ningxia promotes wolfberry as a local strategic advantage of leading industry. Driven by Ningxia, the planting of wolfberry has expanded into other regions of China,and the planting area is specially enlarged in Xinjiang, Qinghai, Inner Mongolia, and Gansu. Currently, the total planting area of wolfberry in China is over 1.33×105 ha. Development of the wolfberry industry in China, especially in the northwest arid area, not only protects the fragile ecological environmentand effectively increases the economic efficiency for farmers, but also solves the employment problem of surplus labor and maintains social stability, which results insignificant social, economic, and ecological benefits. The production areas of wolfberry are mainly in northwest China. These areas differ in ecology and climatic conditions greatly, such as altitude, drought, salinity, sunshine hours, diurnal temperature difference, as well as soil nutrient status, which affect the development of wolfberry fruit and the formation of functional components inside. Dong et al. (2009) analyzed the total flavonoid content of wolfberryfrom five areas of China and found that the total flavonoid content was ranked as: Zhongning (Ningxia)>Shahai (Inner Mongolia)>Nuomuhong(Qinghai)>Qitai (Xinjiang)>Jinghe (Xinjiang)>Julu (Hebei). Zheng et al. (2010) tested the sugar content of two wolfberryvarietiesfrom Ningxia, Inner Mongolia, Xinjiang, and Hebei altogether four regions, and results showed that the different levels of soil salt, pH, organic matter, and available nitrogen affected sugarcontent. Zhang et al. (2012) analyzed the 100-kernel weight of ‘Ningqi 1’ dried wolfberry fruit producedfrom six regions, and found that they were different and in the following order: Qinghai>Gausu>Xinjiang>Xingxia>Inner Mongolia>Hebei. Linnan et al. (2013) evaluated the wolfberry fruits from Ningxia, Gansu and Qinghai and found that climate had great effects on the development of external phenotype and internal quality of wolfberry fruit. Zhang et al. (2014a, b) investigated external traits and internal nutrient contents of three varieties of wolfberry fruits from three planting regions, indicating that the 100-kernel weight and fruit shape index of wolfberry fruit produced in Nuomuhong (Qinghai) were higher than thoseproduced in Tongxin (Ningxia) and Wusu (Xinjiang), while the active ingredientcontents varied greatly with different planting regions. Even inTongxin of Ningxia,a geo-authentic habitat of wolfberry, the intrinsic qualitiesof wolfberrywerealso affected by soil nutrients and salinity and the intrinsic composition variedsignificantlywith different planting locations (Léchaudel et al., 2005; Niu et al., 2005; Xu et al., 2005; Zhang et al., 2005a, b; Kang et al., 2008; Liu et al., 2015). In previous studies, researchers analyze the intrinsic nutrient composition of wolfberry fruits from differentareas and obtained some valuable results. However, these studies suffer from a small number of sample sites and the sampling method is not clearly explained, therefore, these samples may not accurately represent the characteristics of wolfberryfrom typical ecological areas. In this study, we collected wolfberry samples from various sites in typical ecological regions where
2 wolfberry is grown, and analyzed their main nutrient ingredients and related growing conditions, thereby revealing the key factors influencing the intrinsic quality of wolfberry. This study would provide a theoretical basis for evaluation of wolfberryquality from different producing regions.
2. Sampling area and sampling methods
2.1 General information of sampling area
This study is based on the five main wolfberry production regions in China, which include Ningxia, Xinjiang, Qinghai, Inner Mongolia, and Gansu. Samples are specifically collected from seven typical wolfberry areas in the five regions, which are Wulateqianqi and Hangjinhouqiin in Inner Mongolia, Yinchuan City and Zhongning County in Ningxia, Jingyuan County of Gansu, Nuomuhong Farm in Qinghai, and Jinghe County in Xinjiang. Detailed climate conditions of each sampling area are in Table 1. In the seven sampling areas, altitudes range from 290 to 2780 ma.s.l.; the annual mean temperatures range from 5.2 to 10.5°C; annual precipitations range from 42.2 to 243.9 mm; annual sunshine durations range from 2700 to 3220 h, and mean diurnal temperatures range from 11.8 to 15.2°C. Overall, the climates of the seven sampling areas accuratelyreflect the distribution of climates for wolfberry cultivation in China. For example, among these areas, Zhongningin Ningxia has a moderate altitude and sunshine duration, but hasthe highest annual mean temperature, annual rainfall, anda largerdiurnal temperature. While, Nuomuhongin Qinghai hasthe highest altitude and the largest diurnal temperature among the seven areas, butits annual temperature and rainfall is relatively low.
2.2 Wolfberry fruit sample
As ‘Ningqi 1’ could represent the wolfberry varieties of northwest of China, it was chosen as study materials. From each of the seven sampling areas, we randomly selected six-twelve wolfberry gardens where 6-8-year old ‘Ningqi 1’ was cultivated. Then we collected a total of 3 kg of wolfberry fruit with peduncle from different parts of the three trees. All the samples were obtained at the best harvest time. In total, 67 wolfberry fruit samples were collected. These samples were numbered, dried in time and vacuum packed for further analysis.
2.3 Nutrient evaluation and analysis
The seven main nutrient ingredients and four trace elements of wolfberry fruit were evaluated, which included LBP, fructose, glucose, sucrose, carotenoids, betaine, flavonoid, and iron, manganese, selenium, and zinc. The contents of total sugar, LBP, fructose, glucose, and sucrose in wolfberry fruits were analyzed according to the GB/T 18672-2002 (2008). Carotenoids, betaine, iron, manganese, selenium, and zinc contents were measured by high performance liquid chromatography (HPLC). Flavonoid content was determined using a spectrophotometer (Macy Instrument, Shanghai, China). Data was analyzed and plotted using Excel 2003 (Microsoft, USA) and SPSS 20.0 (IBM, USA).Analysis of variance (ANOVA) and least significant difference (LSD) test was performed at a probability level of P<0.05 in SPSS 20.0 (IBM).The nutrient ingredients were analyzed and
3 compared by Student-Neuman-Keuls single factor ANOVA. The relationship among nutrient ingredients and the relationship between nutrients ingredient and environment factor were analyzed by bivariate correlation analysis in SPSS 20.0 (IBM). And the sugar-alkali ratio of all samples was analyzed to make a nationwide regional classification using the Kolmogorov-Smirnov test in SPSS 20.0.
3. Results
3.1 Difference in nutrient of wolfberry fruit from each producing area
Seven main nutritional components of 67 wolfberry fruit samples were measured and analyzed by Student-Neuman-Keulssingle factor of ANOVA. The results were summarized in Table 2. Even though the seven sampling areas were main wolfberry cultivation areas in China, the produced wolfberry fruits showed greatly difference in nutritional ingredients, and the wolfberry fruit in each area had special characteristics. Particularly, the wolfberry fruit from Zhongning, where is a traditional wolfberry geo-authentic habitat in Ningxia, contained the most content of LBP that was much higher than those produced from the other six areas. Besides, the flavonoid and carotenoid contents in Zhongning wolfberry fruit were nearly the same as those in Jingyuan and Nuomuhong, but were significantly higher than those from Yinchuan, Jinghe, Wulateqianqi and Hangjinhouqiin.While the total sugar of wolfberry fruit from Zhongning was significantly lower than that of wolfberry fruits produced in the other six areas. Jinghe in Xinjiang produced nearly the same quality of wolfberry fruit as Yinchuan of Ningxia. The wolfberry fruit in the two areas both contained much more betaine content than the fruits in other areas, and their total sugar contents were relative high.The wolfberry fruits from Hangjinhouqi and Wulateqianqi in Inner Mongolia contained higher total sugar content and tasted better. The wolfberry fruit from Nuomuhong of Qinhai had lower LBP than that from Zhongning of Xingxia, but it had the advantages of bigger size, higher yield, and higher grade rate, then higher market share and better economic benefit, which was the main reason for the rapid development of wolfberry industry in Qinhai Province.
3.2. Difference in trace element of wolfberry fruit from each producing area
As trace element was also important index for evaluating wolfberry quality, it was measured for the 67 samples in this study. As shown in Table 3, the iron content was within the range of 52.30-118.52 mg/kg, and the fruits from Yinchuan, Zhongning, Jingyuan and Jinghecontained the top fouriron contents among the seven areas. The higher manganese contents were found in the wolfberry fruits from Wulateqianqi, Yinchuan, Zhongning, and Jingyuan. As for zinc, it varied greatly in the wolfberry fruits of different production areas, with the highest and lowest value being in Jinghe(18.06 mg/kg) and Wulateqianqi (2.28 mg/kg), respectively. Besides, the wolfberry fruits from Hangjinhouqi and Yinchuan had nearly the same zinc content as in Jinghe. The three highest selenium content values were obtained in the wolfberries from Zhongning, Jinghe and Jingyuan, and the wolfberry fruits of the three areas also had higher iron content. Combing the above results, the four wolfberry cultivation areas, Yinchuan, Zhongning, Jinghe and Jingyuan, could produce fruits containing relatively higher content of three trance
4 elements. While among the seven areas, Nuomuhong produced wolfberry fruit containing the least of all the four elements analyzed in this study.
3.3 The sugar-alkali ratio analysis of wolfberry fruit samples
As total sugar and betaine are two main substances of wolfberry fruit, and their contents and sugar-alkali ratiodetermine wolfberry fruit quality, we analyzed the sugar-alkali ratio of 67 wolfberry samples from seven production areas by Kolmogorov-Smirnov test. The lowest sugar-alkali ratio was 22.64, and the maximum was 318.82, with a variable coefficient of 64.99% (Sigma=0.071＞0.05), which indicated that the sugar-alkali ratio followed a normal distribution (Fig. 1). Based on the normal distribution of sugar-alkali ratio, wolfberry fruits were divided into five quality levels at four division points of (X-1.2818S), (X-0.5246S), (X+0.5246S), and (X+1.2818S), where, X represented the mean of sugar-alkali ratio and S was standard deviation.From the first to fifth levels, the wolfberry fruits had sugar-alkali ratio of0-15.1 (high betaine low sugar), 15-60 (high betaine medium sugar), 60-121 (medium betaine medium sugar), 121-165 (medium betaine high sugar), and greater than 165 (low betaine high sugar) (Table 4). For the 67 samples in this study, the first, second, third, fourth and fifth levels of wolfberry fruit accounted for 0, 37, 42, 10, and 11%, respectively. According to above classificationstandard, Hangjinhouqiwas a low betaine high sugar wolfberry production area;Wulateqianqiwas a medium betaine high sugar wolfberry production area; Jinghe and Yinchuan were high betaine medium sugar wolfberry production areas; and Jingyuan, Zhongning, and Nuomuhongproduced wolfberry fruits with medium betaine medium sugar, that is, the three areas could produce wolfberry fruit with a balanced sugar-alkali ratio.
3.4 Correlations among nutrients of wolfberry fruit
Internal nutrients of wolfberry fruitwere evaluated usingbivariate correlation analysis. As shown inTable 5, flavonoids substance was positive correlation with carotenoid significantly, but was significant negative correlation with fructose and glucose. Both carotenoid and LBP contents were significant negative correlation with fructose and glucose.
3.5 Comprehensive evaluation of nutrients of wolfberry fruits produced in different areas
The quality indexes of wolfberry fruit were analyzed by principal component analysis (PCA). The contents of betaine, flavonoids, carotenoids, LBP, selenium, manganese, iron and zinc were represented by X1-X8. The eigenvalues of the first principal component (PC1), the second principal component (PC2) and the third principal component (PC3) were all greater than 1, and the cumulative variance contribution rate reached 87.825% (Table 6).As the first three principal components reflected most of the original variable’s information, they were extracted instead of the original eight indicators to evaluate the intrinsic nutrition of wolfberry. The initial eight indexes were reduced to three main components that were unrelated to each other, thus achieving the purpose of reducing dimension. The greater the absolute value of the principal component eigenvector was, the greater its representativeness of the variable was.
5 We then analyzed wolfberry nutritional ingredients using the following evaluation function:
F=0.5097F1+0.2247F2+0.1439F3
Where, F was comprehensive assessment value of wolfberry nutritional ingredients; F1, F2, andF3represented the assessment values of PC1, PC2, and PC3, respectively. According to the comprehensive evaluation model, the comprehensive scores and sequencing results of wolfberry in different areas were calculated and shown in Table 7.Based on the nutritional components, the wolfberry fruits produced inZhongning, Nuomuhong and Jingyuanranked the first, second, and third best three qualities, respectively, while the fruit produced inWulateqianqi, Yinchuan, Jinghe, and HangjinHouqihad poor quality. It could be preliminarily concluded that the wolfberry fruit from the geo-authentic habitat, Zhongning, was better than the ones from other areas at both main functional component and microelement levels.
3.6 Correlations among wolfberry nutrient compositions and environmental factors
The relationship between wolfberry nutrient ingredients and the metrological factors of production region was explored by bivariate correlation analysis. Result showed that flavonoids content of wolfberry was (extremely) positively correlated with attitude (r=0.914, P＜0.01) and average diurnal temperature (r=0.851, P＜0.05); betaine content was extremely negatively correlated with annual sunshine hours (r=-0.879, P＜0.01), namely sugar-alkali ratio was extremely positively correlated with annual sunshine hours (r=0.878, P＜0.01) (Table 8).
4. Discussion
Wolfberry is a traditional Chinese medicinal herb. In the long-term practice of Chinese medicine, authenticity has always been a comprehensive standard for evaluating the quality of herbs (Qian et al., 2014; Liu et al., 2014). Genuine medicinal materials are strongly regional: only the herbs produced in a specific region will have high content of active ingredients. The current Chinese pharmacopoeia clearly stipulates that the dry and mature wolfberry fruitproduced in Ningxia is the only certified product (Dong and Wang, 2009), so Ningxia is the only geo-authentic habitat of wolfberry fruit. However, with the expansion of wolfberry across the country, especially the increasing of new producing areas in Qinghai, Inner Mongolia, and Xinjiang, the status of traditional geo-authentic habitat of Ningxia has been threatened. Usually, consumers cannot choose the correct origin of based on their own needs from the variouswolfberries on the market. At the same time, for their own economic interests, trade companies advocate and overly exaggerate the nutritional value of their own wolfberry products in the absence of scientific evidence, causing market disorder and negatively affectingconsumers. This study analyzed the differences in the mainefficaciouscomponents of wolfberry from different areas, providing referencedata for evaluatingwolfberry from different producing areas and theoretical guidance for selectingthe producing area of wolfberry. In this study, the wolfberry fruit samples from Zhongning is the best in quality, which contain the highest content of LBP (main pharmacological ingredients) and the most satisfying sugar-alkali ratio compared with the samples from the other six areas, confirming that Zhongning of Ningxia is the geo-authentic habitat of wolfberry. Besides, the wolfberry fruits from Jingyuan in Gansu and Nuomuhong in Qinghai contain more pharmacological ingredients (LBP, flavonoids
6 and carotenoids), but they contain more total sugar leading to sugar leaning or blocking in fruit. While the wolfberry fruits from Hangjinhouqi and Wulateqianqi in Inner Mongolia, and Jinghe in Xinjiang were higher in betaine and total sugar contents, but lower in LBP content. In addition, people favorite food rich in trance element. The wolfberry fruit from Zhongning of Ningxia was rich in iron, manganese and selenium these three trance elements, which further prove that Zhongning wolfberry is excellent. The classification of sugar-alkali ratio was firstly conducted by Gao and Li in 2003, while the materials’ source in their study was not clear. Later, according to eight wolfberry samples in Ningxia, Zhang et. al. (2008) classified wolfberry fruits into three quality groups (levels): high betaine low sugar (sugar-alkali ratio<30), medium betaine medium sugar (30
With altitude increasing, the environment becomes more unfavorable for plants. Temperature, air pressure, and CO2 partial pressure decrease, while the light intensity and the temperature difference between day and nightincrease (Amagase et al., 2011). Besides, due to the differences in microtopography, various environmental factors at same location would be different. Plant growth and quality formation are a combination of multiple environmental factors (Guo et al., 2015). In different environmental conditions, plants have developed special physiological mechanisms to resist external stress, which show in many aspects, such as photosynthesis, internal compound composition, external phenotype(leaf, basal diameter, plant height, etc.), and the composition and distribution of the plant communities. Leaf shape, chlorophyll, carotenoid, and other indexes of the plant have been found to change regularly with increasing altitude (Gao et al., 2003; Zhang et al., 2008). The concentration of soluble sugar in plants is proportional to the freezing ability of plants, for soluble sugars prevent intracellular icing by reducing the freezing point of the cytoplasm, so that the plant can safely survive the low temperature season (Kang et al., 2008). In contrast, the starch content is inversely proportional to the concentration of soluble sugar and the freezing ability of plants (Amagase and Farnsworth, 2011; Bondia-Pons et al., 2014). Lin et al. (2008) found that the content of soluble carbohydrate in plant increased with the increase of altitude by comparing the contents of soluble carbohydrate in the same tree species from high and low altitudes. In the present study, altitude only affects flavonoids content of wolfberry fruit. And wolfberry fruits in Nuomuhong, Jingyuan and Zhongning, where attitudes are relatively higher among the seven areas, contained more flavonoids than those from the other four producing areas. Although
7 Zhongning altitude is not too much higher than Yinchuan, Wulateqianqi and Hangjinhouqi, but the wolfberry fruits from the four areas are significant difference in flavonoids content, which indicating that altitude is not the single influencing factor of flavonoids. Because annual sunshine hours has negative effects on betaine, thus positively related with sugar-alkali ratio. Wulateqianqi, Hangjinhouqi and Nuomuhong are the three areas with more annual sunshine hours than the other four regions, while the wolfberry fruit in Nuomuhong has a balanced sugar-alkali ratio. In additionJingyuan wolfberry also has balanced sugar-alkali ratio, although its annual sunshine hours was the least. LBP is not significantly affected by any single environmental factors analyzed in this study. All these results indicated that wolfberry quality is formed by comprehensive effects of environmental factors. As both altitude and location conditions contain many factors, it is difficult to determine how that key factor contributes to the medicinal quality of the plant. Likewise, the key factor affecting medicinal quality is not known for wolfberry quality. This is a major problem, as new producing areas emergecontinuously and the wolfberry industry develops quickly nationwide. Therefore, it is crucial to determine the key influencing factors of wolfberry quality and to identify wolfberry geo-authentic habitats for evaluating whether the wolfberry fruits from new producing areas can meet for medicinal and food requirements.
5 Conclusion
This study analyze the nutrients and corresponding environmental factors for the 67 ‘Ningqi 1’ wolfberries collected from seven typical wolfberry production areas in northwest of China. We found that the nutrient composition and trance element of wolfberry fruit varies greatly in different producing areas. In addition, we analyze the ratio of total sugar to betaine (sugar-alkali ratio) of these samples and divide wolfberry fruits into five quality levels: high betaine low sugar (sugar-alkali ratio≤15.1), high betaine medium sugar (15
Acknowledgements
This work was financially supported by the National Natural Science Foundation of China (31460211),Agro-Technical Independent Innovation SpecialProject of Ningxia Hui Autonomous Region, China (QCYL-2018-04).
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10 Table Table 1 Climatic conditions of different production areas of LyciumbarbarumL. Table 2 Statistics analysis of nutritional ingredients of wolfberry fruit from different production areas Table 3 Analysis of variance for trace elements in wolfberry fruits from different producing areas Table 4 Classifications of wolfberry fruit based on its sugar-alkali ratio Table 5 Correlation coefficients among nutritional components in Lyciumbarbarum fruit Table 6 Eigenvectors, eigenvalues, account and total account of three principal components Table 7 Ranking of internal nutrients of wolfberry fruit produced in different areas Table 8 Correlation analysis between meteorological factors and nutrient composition in wolfberry fruit
Figure captions Fig. 1 The normal distribution of sugar-alkali ratio of wolfberry fruits in this study
Table 1 Climatic condition of different production areas of LyciumbarbarumL. Annual Mean diurnal Mean Annual Altitude sunshine temperature Production area temperature precipitation (m) hours difference (°C) (mm) (h) (°C) Wulateqianqi, Inner 1012 8.4 216.3 3202 12 Mongolia Hangjinhouqi, Inner 1032 7.9 136.8 3220 13.2 Mongolia Nuomuhong, Qinghai 2780 5.2 42.2 3158 15.2 Yinchuan, Ningxia 1080 10.1 180.0 2734 12.5 Zhongning, Ningxia 1370 10.5 243.9 2970 13.4 Jinghe, Xinjiang 290 8.2 112.3 2700 11.8 Jingyuan, Gansu 1920 8.9 240.0 2700 13
Table 2 Statistics analysis of nutritional ingredients of wolfberry fruit from different production areas
Betaine Flavonoi Carotenoid LBP Fructose Total sugar Glucose Sugar-al Producing area content dconten content content content content (%) content (%) kali ratio (%) ts (%) (‰) (%) (%) Hangjinhouqi, Inner 23.76 3.52 Cd 0.33 Bb 0.84 BCb 3.95 Bb 59.57 Aa 21.64 BCb 169.23 Mongolia Aa Wulateqianqi, Inner 19.95 4.25 Cd 0.33 Bb 1.21 A Ba 4.37 Bb 54.72 ABab 18.00 Cc 128.75 Mongolia Aa 21.13 Jinghe, Xinjiang 15.77 Aa 0.36 Bb 0.64Cb 3.74 Bb 52.52 ABab 25.77 ABa 33.30 Aa 22.62 Yinchuan, Ningxia 12.77 Aa 0.36 Bb 0.71Cb 3.94 Bb 52.77 ABab 27.57 Aa 41.32 Aa Zhongning, Ningxia 7.39 Bbc 0.59 Aa 1.54 Aa 7.53 Aa 48.74 Bb 9.16Cc 7.67 Dd 65.95 14.35 Jingyuan, Gansu 8.62 Bb 0.66 Aa 1.56 Aa 4.87 Bb 54.03 ABab 11.25 Dd 62.68 Bb Nuomuhong, 5.83 Bc 0.87 Aa 1.47 Aa 4.79 Bb 53.28 ABab 12.51 9.92 Dd 91.39
11 Qinghai BCb Note: The lowercase and capital letters within the same column mean significant difference at 5 and 1% levels, respectively.
Table 3 Analysis of variance for trace elements in wolfberry fruits from different producing areas
Producing area Iron (mg/kg） Manganese (mg/kg) Zinc (mg/kg) Selenium (mg/kg) Wulateqianqi, 61.76±10.51 BC 10.20±0.70 A 15.42±1.07 AB 0.031±0.003 BC Inner Mongolia Hangjinhouqi, 53.46±9.72 C 7.76±0.91 BC 12.74±2.29 B 0.014±0.004 C Inner Mongolia Nuomuhong, 52.30±13.85 C 6.15±1.30 C 2.28±1.54 C 0.030±0.009 BC Qinghai Yinchuan, Ningxia 118.52±19.72 A 9.97±1.75 AB 14.65±4.13 AB 0.015±0.003 C Zhongning, 96.28±43.80 ABC 8.12±0.90 ABC 2.72±1.55 C 0.061±0.018 A Ningxia Jinghe, Xinjiang 80.84±17.29 ABC 7.50±0.67 C 18.06±2.75 A 0.042±0.011 AB Jingyuan, Gansu 103.86±17.60 AB 9.76±0.53 AB 5.99±2.08 C 0.045±0.017 AB Note: The data was analyzed with S-N-K single factor analysis of variance (ANOVA). The same capital letters within the same column mean significant difference at P＜0.01.
Table 4 Classifications of wolfberry fruit based on its sugar-alkali ratio
Sugar-alkali ratio Sample no. Frequency (%) ≤15.1 0 0 15.1-59.6 25 37 59.6-121.3 28 42 121.3-165.8 7 10 >165.8 7 11
Table 5 Correlation coefficients among nutritional components in Lyciumbarbarum fruit
Correlation Flavonoids Carotenoid LBP Total sugar Fructose Glucose coefficient (r) Betaine -0.195 -0.509 -0.238 -0.452 0.191 0.514 Flavonoids 0.772* 0.448 -0.348 -0.817* -0.798* Carotenoid 0.711 -0.343 -0.886** -0.973** LBP -0.669 -0.854* -0.777* Total sugar 0.668 0.360 Fructose 0.927**
Note: *and ** indicate significant difference at 0.05 and 0.01, respectively.
Table 6 Eigenvectors, eigenvalues, account and total account of three principal components
Eigenvectors PC1 PC2 PC3
X1 -0.220 0.638 -0.059
X2 0.453 0.126 -0.213
X3 0.462 -0.099 0.265
X4 0.349 0.187 0.395
X5 0.403 0.271 -0.127
X6 -0.115 -0.246 0.754
12 X7 -0.153 0.630 0.372
X8 -0.461 -0.048 -0.039 Eigenvalues 4.078 1.797 1.151 Variance contribution rate 50.974 22.466 14.386 (%) Total contribution rate 50.974 73.440 87.825 (%)
Table 7 Ranking of internal nutrients of wolfberry fruit produced in different areas
Producing area F1 F2 F3 F Ranking Wulateqianqi, Inner -0.778 -1.775 0.901 -0.666 4 Mongolia Hangjinhouqi, Inner -1.212 -1.736 -0.787 -1.121 7 Mongolia Nuomuhong, Qinghai 2.740 -0.121 -1.467 1.158 2 Yinchuan, Ningxia -2.078 0.991 0.768 -0.726 5 Zhongning, Ningxia 2.081 1.070 0.985 1.443 1 Jinghe, Xinjiang -2.104 1.577 -1.116 -0.879 6 Jingyuan, Gansu 1.350 -0.006 0.715 0.790 3
Table 8 Correlation analysis between meteorological factors and nutrient composition in wolfberry fruit
Betaine Flavonoids Carotenoid LBP Total sugar Fructose Glucose Altitude -0.447 0.914** 0.748 0.298 -0.079 -0.642 -0.727 Average 0.312 -0.473 -0.116 0.368 -0.392 0.029 0.168 temperature Annual -0.071 -0.265 0.302 0.459 -0.263 -0.179 -0.193 precipitation Annual sunshine -0.879** 0.050 0.216 0.079 0.441 -0.016 -0.277 hours Average diurnal temperature -0.453 0.851* 0.572 0.342 -0.040 -0.587 -0.650 difference
Note: *and ** indicate significant difference at 0.05 and 0.01, respectively.
13 Fig. 1 The normal distribution of sugar-alkali ratio of wolfberry fruits in this study.
14