Comparison on Growth Dynamic and Indicator Components of Different Germplasms of Lycium Ruthenicum

COMPARISON ON GROWTH DYNAMIC AND INDICATOR COMPONENTS OF DIFFERENT GERMPLASMS OF LYCIUM RUTHENICUM YEHONG GUO1, QIAN LI1, MEI HUI1, MEIYING LI2 AND AIMIN WANG1 1 College of Agronomy, Institute of Traditional Chinese Medicine, Key Laboratory of Traditional Chinese Medicine Standardization Production Technology Innovation, Gansu Agricultural University, Lanzhou 730070, Gansu, People’s Republic of China 2 Gansu Endangered Animal Protection Center, State Forestry Administration, Wuwei 733000, Gansu, People’s Republic of China Corresponding author’s email:[email protected]; Cell number:+86 13519652912; Abstract This study report a comparison of growth dynamics, chlorophyll content of fresh leaves, main components content in fruits -including polysaccharides, total flavonoids, anthocyanins and proantho cyanidins, moisture, total ash, and extract for three germplasm samples of Lycium ruthenicum. Plant height, stem diameter, and branch number of the three germplasm samples all increased with time, but the growth rate was different in each case. Among the materials tested, Qinghai strains showed the maximum plant height, on August 31st, while the average height was 104.87 cm. Minqin Qingtuhu strains showed the largest stem diameter, on August 31st, while the mean value was 1.06 cm. However, the branch number of Wuwei, the native wild type Lycium ruthenicum, decreased after August 8th. Minqin had the highest chlorophyll content (39.92 mg/g). Qinghai had the highest chlorophyll b content (chlorophyll b and total chlorophyll were 13.05 mg/g and 51.96 mg/g, respectively). Polysaccharide, anthocyanin content, moisture content, and amount of extract from Qinghai were highest. Total flavonoid and ash contents were highest in Wuwei strains. Lycium ruthenicum introduced from Qinghai were the dominant strains and had better nutritional properties than the other two strain collections. Overall, results indicate that Qinghai Lycium ruthenicum is suitable for planting in the Wuwei area. Key words: Lycium ruthenicum; growth dynamic; index component; introduction cultivation Introduction Lycium ruthenicum Murray is a perennial flowering shrub that belongs to the Solanaceae. It is also called the Su wolfberry (Yuan et al., 2013; Han et al., 2014). Fruits of L. ruthenicum are rich in unique functional ingredients such as procyanidins and anthocyanins (Zheng et al., 2011; Wang et al., 2011), which are effective natural water-soluble free radical scavengers (Wei, 2014; Duan et al., 2015), with anti-cancer effects. Vitamin and fat content in these fruits are also much higher than in fruits of the close relative, Lycium barbarum L. The fruit also contains polysaccharides, flavonoids, and other nutrients (Liu et al., 2014; Liu et al., 2016; Nzeuwa et al., 2017). L. ruthenicum is a valuable plant with antioxidant effects and useful for the prevention and treatment of cardiovascular and cerebrovascular diseases (Dong et al., 2008; Lin et al., 2012; Lv et al., 2014); It may also be helpful in preventing severe myopia and retinal detachment (Jin et al., 2015; Gong et al., 2016; Tang et al., 2017). L. ruthenicum has long attracted considerable attention worldwide owing to its high nutritional value and remarkable effects on human health. However, no breakthrough with regard to development of cultivation technology for the species has been made despite years of research. Present limitations owing to small scale production and germplasm scarcity are still key problems that limit industrial development of L. ruthenicum (Wang et al., 2011; Shen et al., 2012; Wang et al., 2014). In this work, the growth dynamics of the aboveground parts of L. ruthenicum, the anthocyanin content (Guo et al., 2016; Ma et al., 2017), and other indicators were studied to comprehensively evaluate the growth adaptability, fruit active ingredients, and quality advantage of L. ruthenicum (Lin et al., 2013; Li et al., 2017). This work aimed to provide a scientific sound basis for improving ecological adaptability, yield, quality, and standardized production and cultivation guidelines for L. ruthenicum. Our work can thus promote the cultivation of fine varieties and the expansion of the L. ruthenicum industry chain. Materials and Methods Experimental area: The experiment field is located northwest of Wuwei city (Gansu province) on the southwest margin of the Tengger Desert, which is characterized by a typical temperate continental climate. Geographic coordinates are longitude 102°43′-103°22′, latitude 38°05′-38°20′, and elevation 1632 m. The mean annual precipitation is 210 mm, evaporation volume amounts to 2600–3010 mm, and activity accumulated temperature is about 3003 ℃; The day/night temperature difference is 15 ℃ or more; The number of sunshine hours is usually around 3039, the frost-free period is 85–165 d. Light, heat, water, and soil conditions are suitable for L. ruthenicum cultivation. Experimental plant materials: The experiment was conducted from April 2016 through April 2017, at the National Forestry Administration of Gansu Endangered Animal Protection Center and at the General Laboratory of Gansu Agricultural University. Test materials included introduced an L. ruthenicum Qinghai (QH) germplasm collection; Wuwei (WH), a native wild type; and Minqin Qingtuhu (MH), a native wild type. The experiment was laid out as a single-factor randomized block design with three treatments and three replications; the experimental plots were 3 m × 6 m = 18 m2. Ten strains of L. ruthenicum were randomly selected from each district and marked. Mature leaves were sampled at 23-d intervals, placed in preservation bags, and brought back to the laboratory for analysis. Experimental methods: Measurement of aboveground growth index of three different L. ruthenicum germplasm samples: Plant height, stem diameter and branch number were measured at 23-d intervals starting May 22nd. A total of 10 strains single plants were measured with a tape gauge and a Vernier caliper. Determination of chlorophyll in leaves of different germplasm samples of L. ruthenicum: Chlorophyll content was determined and calculated as described by Mu et al. (2005). Polysaccharide extraction and determination: Polysaccharide content was extracted and determined as described by Zhang et al. (2006) and Lin et al. (2013). Preparation of standard curve: Anhydrous glucose (50.0 mg) was accurately weighed and transferred to a volumetric flask (50 mL), after which water was added to bring the solution to volume; 1.0, 2.0, 3.0, 4.0, 5.0 mL aliquots of this solution were drawn and transferred into 50 mL volumetric flasks, and again distilled water was added to bring the solution to volume. Finally, 1.0 mL aliquots of each standard solution were transferred into plug test tubes. Absorbance was determined according to the method described below (2.3.3.2). The standard curve was drawn with absorbance value as the abscissa and concentration (C) as the ordinate, and the regression equation was calculated. Precision experiment: Precise removal of the reference solution 1 mL and was set to 25 mL volumetric flask, respectively. One mL of each test solution was placed in a 10 mL plug test tube. The absorbance value was measured under 365nm and the RSD（Relative standard deviation） value was calculated (n = 5). Reproducibility experiment: Five samples from the same batch of Qinghai L. ruthenicum were accurately weighed. The polysaccharide solution was prepared according to the ultrasonic method, and polysaccharide content was determined and RSD value calculated (n = 5). Stability experiment: Test solution of Qinghai L. ruthenicum was sampled at different times (0.5, 1, 2, 4, and 8 h) to determine the absorbance; the RSD value (n = 5) was calculated in each case. The absorbance value was confirmed to remain constant for at least 8 h. Recovery experiment: One milliliter of a glucose reference solution (1.0 mg/mL) was transferred to a 25 mL volumetric flask. The solution (0.5 mL) was then placed in a 10 mL stoppered tube, to which was added 0.5 mL of a test solution. Absorbance was measured, and average recovery rate and RSD value (n = 5) were calculated. Determination of sample polysaccharide content: One milliliter of test solutions of Wuwei and Minqin Qingtuhu L. ruthenicum samples were placed in 10 mL plug test tubes, respectively. Absorbance was determined and polysaccharide content was calculated according to the following formula: Polysaccharide content (%) = CDf/W × 100 (1) Where, C is the glucose concentration (mg/mL) in the sample; D is the dilution factor for the sample solution; f = 3.17 (conversion factor (Chang et al., 2002); W is the powder quality (mg) of the sample. Extraction and determination of total flavonoid content: Total flavonoids were extracted and reported as reported by Zhang et al. (2006). Determination of procyanidins and anthocyanins: Anthocyanin content was calculated according to the following formula (Wang et al., 2016): MF = (A × V)/(98.2 × M) (2) Where, MF is the content of anthocyanins in the sample (mg/g); A is the absorbance at maximum wavelength; V is volume (mL) × dilution factor; M is the sample weight (g); and the value 98.2 is the average extinction coefficient of anthocyanin. Determination of moisture, total ash, and extract content: Moisture, total ash, and amount of extract were determined according to "Chinese Pharmacopoeia" (2015 edition). Statistical analysis:Excel 2013 software was used to generate images and the Duncan method was used for statistical analysis in SPSS 20.0 software. Results and Discussion

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