| With field conditions of longjing43 tea plants and potted condition of the longjing 43 seedings as experimental material,the main researches were on the following two aspects:(1) The biomass, nutrient concentrations (fractions in dry matter base) and contents (fractions in soil volume base) in fibrous roots of tea plants during July to next January in a 12-years-old field plantations which received defined but variable nitrogen fertilizer rates (0,285 and 715 kg/ha) for 5years by soil core sampling method. (2) The root architecture,nutrient concentrations and contents of roots, soluble sugars and the main contents of amino acid composition were affected by different soil textures.To clear the soil factors(texture,nutrient) influence on root growth and root architecture of tea plants,and for further study of roots efficiently absorb nutrients. The result were as followed:(1) The biomass of fibrous roots was between 0.34-0.72 g·dm-3 and the contents of carbon, nitrogen, phosphorus, potassium and magnesium were 12.6～25.2 g · dm-2, 4.55～11.2 g·dm-3,0.47～1.19 g·m-3,1.31～4.05 g·dm-3,0.30～1.19 g·dm-3, respectively. The biomass and nutrient contents of fibrous roots showed bimodal distribution, being the highest in August and January and the lowest in July and November. Effect of variable N fertilizers on biomass of fibrous roots under field conditions had changing roles as initial promotion in a short time after fertilization and later inhibition over a long time.(2) Nitrogen fertilization had no significant effect on carbon concentration and content, but reduced the concentrations and contents of P, K and Mg. Effects of N fertilization rates on N concentration and C/N varied among months, showing a short-term inhibition effects while only marginal effect on N contents. Variation ranges of nutrient contents during summer and autumn were narrowed in the treatment receiving medium N application rate at 285 kg/ha. The results suggested that the growth and nutrient contents of fibrous roots was coordinated in accordance with those of above-ground.(3) Under different soit textures conditions, S2 had larger roots, total root length, the number of lateral roots, root surface area and root volume, which were superior to the other two treatments. The number of lateral roots and tips, total root length, root surface area of S1 were significantly less than S2, but did not differ significantly in the root volumebetween S1 and S2. The number of roots and lateral roots, total root length and root volume of S3 were least, while there was no significant difference in root surface area between S1 and S3. Overall, the fine roots of S2 were dense and thick roots were in the medium level, S1 had more fine roots but thick roots were weak, the numbers of fine roots of S3 were less, while thick roots were at most.(4) Under different texture soils, root biomass were mainly caused by root architecture, the root biomass of S2 was significantly higher than S1 and S3. The difference of nitrogen concentration was also associated with root architecture. The seedings with longer root and bigger root volume could took nitrogen easily. This study indicated no significant differences in phosphorus and potassium absorption rate.(5) Under different texture soils, the soluble sugar contents of each part of tea were different. Tap roots had the highest cumulative content, and S1 accumulated the most. Similarly, sugar contents were different in the fine root. S2 maximumly accumulated sugar contents in the fine root. The main amino acid components of fine root were all higher than that of tap root. |
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