| Dioscorea opposita Thunb. is one of the Four Famous Huai Medicine. D. opp. Thunb. cv. Tiegun is an superior variety of D. opp. Thunb. Since ancient times, there is saying"Yam is a big stick ginseng". At present, in our country, there is not the relevant quality standards for Tiegun nursery, this results in no criteria to guide the production, nursery intermixing, and poor composition or loss of efficacy. To solve the above problems, head parts of tuber and sigments of tuber were taken as experimental materials, nursery quality standards of Tiegun had been studied in this paper at home and abroad for the first time and achieved the following results:1. Grade standard of head parts and sigments from tubers of Tiegun has been defined. There is no disease and pest for grade 1, 2, 3. About head parts of tuber, Grade 1, Encircles diameter≥1.1 cm, weight≥20 g, length≥26 cm, clarity≥90%, plumpness≥90%. Grade 2, 0.6 cm≤Encircles diameter < 1.1 cm, 16g≤weight< 20g, 20cm≤length< 26cm, 85%≤clarity < 90%, 80%≤plumpness≤89%. Grade 3, 0.3cm≤Encircles diameter < 0.6 cm, 10g≤weight< 16g, 15cm≤length< 20cm, 75%≤clarity < 85%,70%≤plumpness < 80%. About segments of tuber, Grade 1, tuber circumference diameter≥2.5 cm, weight≥45.0 g. Grade2, 1.6 cm≤tuber circumference diameter < 2.5 cm, 35.0 g≤weight < 45.0 g; Grade3, 1.0 cm≤tuber circumference diameter < 1.6 cm, 25.0 g≤weight < 35.0 g.2. The basis of healthy degree testing of Tiegun nursery has been defined. There are eight kinds to be tested, including Even bacilli, the ball bacillus, Corynebacterium, thick bacillus, a small, Lactobacillus, bundle stem genera, sticky stem genera. Interior of head parts is taken as testing part and the head parts of tuber are health when their germ-carrying percentage is less than 10%.3. The physiological indexes of identification of Tiegun has been proved up. Water content is about 70%, content of free amino acids is about 14~16 mg /gDW, content of soluble sugar is about 10 ~15 mg/gDW, starch content remaines at 140 ~ 160 mg/gDW, polysaccharide content maintaines at 4 ~ 5 mg/gDW. The head parts of Tiegun tuber are fitting for the above characteristics.4. The relationship between grade of head parts of tuber and growth-development has been proved. Grade of tuber head parts has a positive correlation with the maximum leaf length, the maximum leaf width, stem diameter, chlorophyll content, photosynthetic rate.5. The relationship between grade of head parts and segments of tuber and yield and qulity has been proved. Grade of tuber head parts has a positive correlation with weght of per plant, yield per mu, yield of bulbils, head parts of tuber by produced. That is, the first grade has the most each plant weight(about 290~300 g), the highest yield per mu(about 1000~1100 kg), the highest bulbil yield(about 250 kg), the maximum yield of the first grade (about 60%), the second grade is higher, tha third is lowest. Grade of tuber head parts has a positive correlation with free amino acids, soluble protein, soluble sugar, polysaccharide, starch contents. That is, the first grade has the highest contents of free amino acids, soluble protein, soluble sugar, polysaccharide, starch, 17.0 m/gDW, 14.8 mg/gDW , 24.5 mg/gDW , 7.5 mg/gDW , 165.2 mg/gDW respectively. the second grade is higher, tha third is lowest. Grade of segment has also a positive correlation with weght of per plant, yield per mu, yield of bulbils, head parts of tuber by produced, and free amino acids, soluble protein, soluble sugar, polysaccharide, starch contents. |
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