Effect of fertilization methods on the quality of Tea

Effect of fertilization methods on the quality of Tea

1 test method

1.1 Test site

The tested tea garden is Wenshan tea garden in Rizhao City, which is located in Donggang District, Rizhao City, Shandong Province, and the experimental tea garden is Huangshan group.

1.2 Reagents and equipment

Main reagents: hydrochloric acid, sulfuric acid, ninhydrin, Folin phenol, anhydrous sodium carbonate, methanol and so on.

Laboratory instruments: DWF-20 electric plant grinder, UV-1800PC UV-vis spectrophotometer, HH-4 digital display constant temperature water bath pot, DHG-9023A electric constant temperature blast drying box, BSA224S electronic balance (sensitivity 0.1mg), TDL-80-2B low speed desktop centrifuge, microwave oven, sensitivity 0.1g tray balance and so on.

1.3 methods for sample analysis

Caffeine: ultraviolet spectrophotometry, GB/T8312-2002 "Tea-caffeine determination". Tea polyphenols: Folin phenol reagent colorimetry, GB/T8313-2008 "method for determination of tea polyphenols and catechins in tea". Amino acids: indene triketone chromogenic method, GB/T8314-2002 "Tea-determination of total free amino acids". Water extract: GB/T8305-2002, determination of tea-water extract.

1.4 Experimental treatment

1.4.1 different fertilization time experiments were conducted to study the effect of base fertilizer application time on tea yield and quality in autumn 2011. The amount of basic fertilizer was 2000 kg of sheep manure, 100 kg of cake fertilizer, 25 kg of superphosphate and 10 kg of potassium sulfate per 667m2. The samples of fresh tea leaves were collected 20 days after spring tea mining, and the main chemical components were analyzed after steaming and fixing. The experiment consists of four treatments: treatment 1: White Dew fertilization; treatment 2: the Autumn Equinox fertilization; treatment 3: Cold Dew fertilization; treatment 4: Frosts Descent fertilization.

1.4.2 the experiment on the proportion of organic fertilizer and chemical fertilizer was carried out in Wenshan tea garden in Rizhao City in 2012. it was designed that organic fertilizer and three-element compound fertilizer were applied in different proportions in autumn. The fertilization time was September 7 and the fertilization depth was 20 cm. The total nutrient content of organic fertilizer is 2.5%, and the content of nitrogen, phosphorus and potassium in compound fertilizer is 15%. Sheep manure is applied every 667 m2. On the basis of 1000 kg, six treatments were designed, that is, treatment of 100% sheep manure, treatment of 70% sheep manure and 30% compound fertilizer, treatment of 30% sheep manure and 50% compound fertilizer, treatment of 40% sheep manure and 70% compound fertilizer, treatment of 5% goat manure and 50% compound fertilizer, treatment 6: no fertilization. The amount of fertilizer used in each treatment is shown in Table 1. The fresh leaves of each treatment were collected in late May of the following year, and the main chemical constituents were analyzed after steaming and fixing.

Table 1 Fertilizer use in different treatments

1.4.3 effect of balanced fertilization of nitrogen, phosphorus and potassium on the quality of green tea.

An experiment was conducted on the effect of the ratio of nitrogen, phosphorus and potassium on the quality of tea in Wenshan tea garden in Rizhao city in 2012. There were three treatments: treatment 1: ratio of nitrogen, phosphorus and potassium 2 ∶ 1 ∶ 1, treatment 2: ratio of nitrogen, phosphorus and potassium 3 ∶ 1 ∶ 1, treatment 3: ratio of nitrogen, phosphorus and potassium 4 ∶ 1 ∶ 1.

Taking the total nutrient content of 50 kg/667 m ~ 2 as the standard, 30% of nitrogen fertilizer and all phosphorus and potassium fertilizer were used as base fertilizer on September 10, and the other nitrogen fertilizers were used as topdressing in spring, summer and autumn according to the ratio of 3 ∶ 2 ∶ 1, and no fertilizer was used as control. Samples of fresh tea leaves were collected in spring and autumn, and the contents of main nutrients were analyzed after steaming and fixing.

2 results and analysis

2.1 fertilization time

The experimental results of different fertilization time are shown in Table 2. It can be seen from Table 2 that the application of base fertilizer sooner or later has a great impact on tea trees. The best period of applying basic fertilizer in Rizhao tea area was before and after White Dew. Fertilization in this period could promote the healing of wounded roots, increase the number of new roots, enhance the tree potential, improve the cold resistance of tea trees, and provide sufficient nutrients for tea bud germination in the following year. White Dew applied base fertilizer, the tea tree germinated early, the bud leaves were thick, and the spring tea water extract was obviously higher, which was beneficial to the improvement of green tea yield and quality.

Organic fertilizer, phosphorus and potassium fertilizer are generally used as base fertilizer in autumn, 30 ~ 40% of nitrogen fertilizer is used as base fertilizer, and the depth of fertilization is 15 ~ 30 cm, which is usually carried out immediately after the aboveground part of tea plant stops growing before and after White Dew (early September). If it is used too late, the root injury is not easy to heal, and the contribution rate of base fertilizer to spring tea will be reduced; if it is used too early, if the temperature is too high in late autumn, it will make some overwintering buds sprout, affect the yield of spring tea in the following year, and is not conducive to tea overwintering.

In the sunny climate, White Dew (early September) before and after the application of base fertilizer, ditching when the root wound is easy to heal, and can produce many new roots, the overwintering effect is good. Frosts Descent (late October) after the application of base fertilizer, the root injury is not easy to heal or non-healing, rotten a lot, the overwintering effect is poor. Therefore, the time of applying base fertilizer should be before and after White Dew, but the Autumn Equinox at the latest.

Table 2 effects of different application periods of base fertilizer on the contents of fresh tea leaves

2.2 ratio of organic fertilizer to chemical fertilizer

The test results of the ratio of organic fertilizer and chemical fertilizer are shown in Table 3. The results showed that the contents of amino acids, tea polyphenols, caffeine and water extracts in treatment 1 and treatment 2 were significantly higher, the ratio of phenol to ammonia was lower, and the endoplasm of tea was significantly improved. The use of organic fertilizer or organic fertilizer combined with a small amount of chemical fertilizer as topdressing in autumn can significantly improve the quality of green tea.

Table 3 average contents of main biochemical components of spring tea under different fertilization treatments

2.3 effect of balanced fertilization of nitrogen, phosphorus and potassium on the quality of green tea

The effect of balanced fertilization of nitrogen, phosphorus and potassium on the quality of green tea is shown in tables 4 and 5. It can be seen from Table 4 that the content of tea polyphenols and amino acids in treatment 2 is the highest, the content of caffeine in treatment 3 is the highest, and the content of water extract is the highest in treatment 2. from the single component, the content of polyphenols in spring tea is not high, the content of amino acid is high, and the content of caffeine is on the high side. The best ratio of N, P and K fertilizer was 3 ∶ 1 ∶ 1, followed by 4 ∶ 1 ∶ 1. According to Table 5, the amino acid content of autumn tea in treatment 2 was the best, but there was no significant difference between treatment 2 and treatment 3. The contents of tea polyphenols and caffeine in treatment 3 were higher than those in treatment 3. The optimum ratio of nitrogen, phosphorus and potassium in autumn tea was 3 ∶ 1 ∶ 1, followed by 4 ∶ 1 ∶ 1.

Table 4 average value of main nutrients of spring tea with different fertilization ratios [Jishan Huayao]

Table 5 average value of main nutrients of autumn tea with different fertilization ratios

The main nutritional components of tea are nitrogen, phosphorus and potassium. Nitrogen is highly positively correlated with the content of tea amino acids and closely related to tea polyphenols and carbohydrates. Phosphorus can significantly increase the content of tea polyphenols. The effect on tea quality is mainly shown in two aspects: aroma and taste; potassium can significantly increase the content of free amino acids and tea polyphenols in tea and significantly inhibit the side effects of soil calcium ions. The interaction of nitrogen, phosphorus and potassium significantly affected the quality of green tea.

3 conclusion and discussion

The best period of applying base fertilizer in Rizhao tea area is before and after White Dew, which is beneficial to the improvement of tea quality, which is consistent with the research conclusion of Wu Aiping [1]. The quality of green tea is the highest when base fertilizer is applied in autumn and pure organic fertilizer or organic fertilizer combined with a small amount of chemical fertilizer, which is consistent with the conclusion of Yin Genhua et al. [2]. Among the nitrogen, phosphorus and potassium application ratio, 4 ∶ 1 ∶ 1 was the best, 30% nitrogen fertilizer and all phosphorus and potassium fertilizer were used as base fertilizer in the first ten days of September, and other nitrogen fertilizers were used as topdressing in spring, summer and autumn according to the ratio of 3 ∶ 2 ∶ 1.