不同施氮水平对胡麻根系形态和氮素利用的影响

Effect of different nitrogen level on root morphology and nitrogen utilization of oil flax

以陇亚杂1号为研究对象,设置4个施氮量(纯N)水平:不施氮(N0,0kg·hm-2)、低氮(N1,78.75kg·hm-2)、中氮(N2,105kg·hm-2)、高氮(N3,131.25kg·hm-2),采用土柱栽培法研究了氮肥运筹对胡麻根系形态和氮素利用率的影响。结果表明:施氮抑制了胡麻枞形期根系的生长,现蕾期后根长、根系直径、根表面积和根体积均随着施氮量增加而增加,当超过一定施氮量(N2)时又呈下降趋势。中氮处理增加了胡麻生育后期根系在40cm以下土层的分布,随着施氮量的增加,根系分布呈现高氮(N3)浅根化趋势。胡麻的根冠比随着生育进程的推进逐渐降低,但中氮处理显著提高了生育后期的根冠比。胡麻成熟期各器官氮素积累量和分配比例表现为:籽粒>茎>根>叶>非籽粒生殖器官,籽粒在氮素的分配上占有绝对优势,而且在中氮水平(N2)时籽粒中氮素分配比例最高,显著高于其他处理。与不施氮相比,施氮处理下籽粒产量增加,中氮水平下的氮素籽粒生产效率最高。综合籽粒产量和氮素利用结果表明,在本试验条件下,施氮量105kg·hm-2为有利于实现胡麻高产和高效的最优氮肥运筹模式。

In order to identify the effect of different nitrogen level on root morphology and nitrogen utilization efficiency of oil flax,a soil column experiment was conducted with 4 pure nitrogen application rate： without nitrogen（ N0）,low nitrogen（ N1,78. 75kg·hm^- 2）,medium nitrogen（ N2,105kg·hm^- 2） and high nitrogen（ N3,131. 25kg·hm^- 2）. Oil flax cultivar Longyaza 1 was used. Results showed that root growth was inhabited by nitrogen application in fir shaped period. However,root length,diameter,surface area and volume initially were raised by the increase of nitrogen,and decreased under N2 after squaring. Root distribution under 40cm-layer soil was increased under N2. Shallow roots increased under higher nitrogen（ N3） application in late growth stage. Root-shoot ratio was gradually decreased along with the growth,but was significantly improved under N2 in late period.Under N2 treatment,grain yield reached the highest. After takeng into account of grain yield and nitrogen utilization,the nitrogen fertilizer rate of 105kg·hm^- 2was recommended.