不同氮素供应对油菜苗期生长及碳氮分配的影响

摘要

为明确不同氮素供应对油菜苗期碳氮积累及其在地上与地下部分配的影响,开展营养液水培试验,蒸馏水育苗移植后即开始全量营养培养.试验设置6个氮素培养浓度,分别为0.01、0.05、0.1、0.5、1.0和6.0mmol/L,每7d取样,动态监测培养35d内的油菜地上和地下部的干物质及碳氮积累动态.结果表明,随氮素营养供应增加,单株叶面积、地上部干物质、各部位氮含量及氮积累量显著增加;根系干物质及碳氮积累量先增加后降低,各部位碳含量不受影响.分别在培养后第7～21d,各处理间以0.1、0.5和1.0mmol/L处理根系物质积累量较高,第28d后根系物质积累随氮素供应增加而增加.增加氮素供应显著降低植株根冠比(R/S).单位面积叶片碳积累速率和单位质量根系氮吸收速率在氮素缺乏条件下,随氮素含量增加而增加.综上可知,氮素供应不足时,碳氮向根系的分配增加,植株碳氮积累速率显著降低,地上部受氮素缺乏影响更大.%To clarify the effects of different nitrogen (N) application on carbon (C) and N accumulation in oilseed rape and the distribution on the aboveground and underground, a hydroponic test was conducted. The seedling was grown in distilled water and cultured with full strength nutrient solution after transplanted. A total of 6 N levels were set for the test, and they were 0. 01, 0. 05, 0. 1, 0. 5, 1. 0 and 6. 0 mmol/L. Dynamics of dry matter, C and N aboveground and underground of oilseed rape within 35 days was investigated every 7 days. The results showed that with the increase of N application, the leaf area per plant, dry matter aboveground, N concentration and accumulation increased significantly. Dry matter, C and N accumulation underground increased as N application added and then decreased. The C concentration of both shoot and root were not affected. The substance accumulation underground of 0. 1, 0. 5, and 1. 0 mmol/L treatment reached the higher level among the treatments on the 7 th, 14 th, and 21 th days after transplanting, respectively. Substance accumulation underground increased as N application increased after 28 d after transplanting. The R/S of dry matter decreased remarkably as N application increased. C accumulation per unit area of leaf and N accumulation per gram root improved with increasing N concentration as the N supply was deficient. Insufficient N supply increased the distribution of C and N to the root and reduced the rate of C and N accumulation in the plants, exerting greater influence on the aboveground.