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作者	单位
高翔，陈磊，云鹏，王盛锋，刘荣乐，汪洪	（1.农业部植物营养与施肥重点实验室，中国农业科学院农业资源与农业区划研究所，北京 100081； 2.中国农业科学院研究生院，北京 100081）

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中文摘要:

为探讨土壤硝态氮非均匀分布条件下小麦根系生长及氮素吸收特征，选用石麦15、衡观35、H10和L14等4个小麦品种为材料，进行土壤分层培养试验，模拟土壤剖面中上下层硝态氮空间分布差异，测定和分析了小麦根系长度、直径、分布等形态学特征及植株氮素含量和累积量。结果表明，当土壤中硝态氮施用量上层较低、下层较高时，小麦植株根系总长和表面积在上下土层中分布比值降低，根系趋向下层土壤生长。上下层土壤中硝态氮施用量均较高时，上下层土壤中的根系总长和表面积比值较大，根系趋向上层土壤生长。土壤剖面不同层次中硝态氮供应非均匀条件下，小麦根系发育呈现明显的可塑性反应。小麦根系总长和表面积以及直径≤0.15 mm的细根长（占整个根系的比重很大）与植株地上部氮含量和氮素积累量极显著正相关，与土壤中硝态氮含量极显著负相关。

英文摘要:

Nitrate (NO₃-) is the main source of inorganic nitrogen for plants in aerobic soil conditions. Little information is available on root morphological characteristics of different wheat genotypes influenced by nitrate spatial supply in soil layers. A soil column experiment with splitting layer was carried out to study the effects of different rates of nitrate application to topsoil and subsoil on root morphology and plant nitrogen uptake of wheat. Four wheat varieties, H10, L14, Shimai 15, and Hengguan 35 were selected as the test materials. The results showed that under the conditions of low nitrate rates in topsoils, more roots distributed to subsoils where nitrate application rates were high as the ratio of total root length and root surface area in upper to lower layers of soil increased. Contrarily, less root length, surface area and biomass allocated in the topsoil where nitrate rates were high as the ratio of total root length and root surface area in upper to lower layers of soil decreased. It is suggested that nitrogen concentration and N accumulation in shoots had significantly positive correlations with total root length, root surface area, and fine root length within 0~0.15 mm diameter, respectively, while the soil nitrate contents showed negative correlations with those parameters of wheat roots. It is suggested that wheat roots displayed considerable developmental plasticity in response to variations of N supply in soil layers. Greater root growth was ocurred in the area with higher nitrate supply. Root phenotypes such as fine root length density and more root surface area were important for improvements to nitrate acquisition and uptake of wheat plants from soils.

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