| This study was based on the coastal areas of 6 year-old,10 year-old,17year-old poplar plantation in Jiangsu,impact studies carried out simulated N deposition on fine roots of poplar, The study randomized block design, set up five applied N concentrations, respectively N0(0 g N·m-2·a-1),N1(5 g N·m-2·a-1),N2(10g N·m-2·a-1),N3(15 g N·m-2·a-1),N4(30 g N·m-2·a-1).To explore the forests with different ages, different seasons and different content root orders of fine roots of poplar plantation carbohydrates, total C, total N, etc. for different concentrations of N deposition processing simulation response mechanism, further fine roots of poplar NSC / SC(structural carbohydrates with non-structural carbohydrate ratio), C / N(N ratio) were analyzed, a preliminary explanation for the whereabouts of simulated N deposition in N elements.The main results and conclusions are as follows:(1) there are some differences of the total carbohydrate, total N, total C content of fine roots in different forest ages, different root orders, different seasons.Total carbohydrate and total N content were made at the maximum 6-year-old conditions were 504.10 mg·g-1 and 6.16 mg·g-1, a full C content is made maximum 500.01 mg·g-1 at 17 year-old conditions were associated with a significant difference from the control(p <0.05).Different root orders, total carbohydrates, total N, C are in the 1-3 root level to achieve the maximum, respectively 524.89 mg·g-1,7.03 mg·g-1,478.74 mg·g-1, they were associated with a significant difference from the control(p <0.05).The season is manifested in the total carbohydrate content made maximum 583.94 mg·g-1in the winter,and total N, C achieved the maximum in the spring, were 5.86 mg·g-1,532.91 mg·g-1, it was associated with a significant difference from the control(p <0.05).In summary, age and root order have a significant impact on the fine roots of poplar carbohydrate and nutrient content,seasonal change is more complex,total carbohydrates minus small but total N, total C levels were increased in spring, it may be associated with each element in the growing season, such as proteins involved in the synthesis of further related.(2) With the applied N concentration increases, reducing the total fine roots after the first non-structural carbohydrate content increases, all treatments were applied N is greater than control(N0), N1 obtain maximum 173.53 mg·g-1, and with significantly different from control(p <0.05), which also achieved the maximum starch content of 151.84 mg·g-1 in N1.The total fine roots in structural carbohydrates(SC) after the content first and then decrease in the N3 obtain maximum 355.19 mg·g-1, and significantly difference with control(p <0.05), wherein the cellulose content in the same N3 obtain maximum 184.96 mg·g-1, the lignin content was no significant change.Total non-structural carbohydrates and structural carbohydrates and NSC / SC maximum achieved in N1, respectively 525.38 mg·g-1 and 50.19%, and with a significant difference from the control(p <0.05).Overall, fine roots response to simulated N deposition on non-structural carbohydrates mainly as affecting their starch content, and in the structural carbohydrates mainly for the impact of its cellulose content, and N1 to the total carbon water compound content and NSC / SC greatest impact.(3) With increasing concentration of applied N, N0-N4 each applied N concentrations of fine roots increases total N content, obtained in N4 maximum of 5.76 mg·g-1, and the total N and N1-N4 are controlled the difference was significant(p <0.05).Full C content at each applied N concentrations were not significantly different.C / N appeared with the total N content the opposite trend, with the increase of applied N concentrations of fine roots C / N decreases, the minimum value obtained 84.27 in N4, and the facilities at N concentrations were associated with a significant difference from the control(p <0.05).Description of the fine roots in poplar, N settlement mainly through its wholly affect N content on its C / N, thereby affecting their life activity and morphogenesis. |
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