CO2浓度升高与施氮对薏苡苗期营养元素吸收运输的影响

为明确大气CO₂浓度升高及氮肥施用对薏苡(Coix lacryma-jobi L.)苗期营养元素吸收运输的影响,本研究以兴仁白壳薏苡为试验材料,采用盆栽控制试验,通过人工气候箱模拟CO₂浓度升高,探究薏苡各器官中营养元素对CO₂浓度升高和施用氮肥的响应。结果表明,CO₂浓度升高使薏苡根中TOC含量显著增加15.82%;叶、茎中TP含量显著增加18.98%、29.41%(P<0.05);叶、根中N含量显著减少8.15%、8.31%(P<0.05);叶、茎、根中K含量无显著差异。施氮使薏苡叶、茎、根中N含量显著增加19.52%、28.42%、23.29%;叶、茎中TP含量显著增加14.60%、51.96%(P<0.05);根中K含量显著减少22.57%(P<0.05);叶、茎、根中TOC含量无显著差异。两者交互作用下,薏苡茎、根中N含量显著增加6.49%、8.99%;叶中TP含量显著增加15.33%(P<0.05);叶中N含量显著减少4.22%;叶、茎中K含量显著减少18.47%、33.25%(P<0.05);叶、茎、根中TOC含量无显著差异。在CO₂浓度升高条件下,薏苡叶片中中量元素S和微量元素Cu、Zn、Ni含量,分别显著减少18.06%、54.01%、37.96%、50.99(P<0.05);而茎中Mn、Cu、Zn、Ni含量,分别显著增加90.20%、70.55%、46.80%、149.50%(P<0.05)。CO₂浓度升高能促进Mg、S根向茎的运输以及Zn、Mn茎向叶的运输,施用氮肥能促进Fe茎向叶的运输。综上所述,CO₂浓度升高和氮肥施用会影响薏苡不同器官矿质离子的吸收及选择性运输能力,从而维持植物体内营养元素平衡。本研究结果可为深入认识未来大气环境变化下,薏苡对营养元素的需求变化特征,以及薏苡栽培中施肥策略的选择提供科学依据。

Effects of Elevated CO2 Concentration and Nitrogen Application on Nutrient Absorption and Transportation in Coix lacryma-jobi Seedling Stage

To clarify the effects of elevated atmospheric CO₂ concentration and nitrogen application on the absorption and transportation of nutrients elements in C. Lacryma-jobi L. seedlings, a pot control experiment, using an artificial climate chamber to simulate CO₂ concentration rising, was conducted to assay the response of elevated CO₂ concentration and nitrogen application on nutrient elements in the roots, stems and leaves of C. Lacryma-jobi L. variety Xinrenxiaobaike. The results showed that, elevated CO₂ concentration significantly increased the content of TOC in C. Lacryma-jobi L. root by 15.82%, and the TP content in leaves and stems by 18.98% and 29.41% (P<0.05). The content of N in leaves and roots decreased significantly by 8.15% and 8.31% (P<0.05), There was no significant difference in K content among leaves, stems and roots. Nitrogen application significantly increased the N content in the leaves, stems and roots of Coix by 19.52%, 28.42% and 23.29%, and the TP content in the leaves and stems by 14.60% and 51.96%, respectively (P<0.05). The content of K in roots decreased significantly by 22.57% (P<0.05), There was no significant difference in TOC content among leaves, stems and roots. Under the interaction of the elevated CO₂ concentration and nitrogen application, the N content in the stems and roots of C. Lacryma-jobi L. increased significantly by 6.49% and 8.99%, and the P content in the leaves increased significantly by 15.33% (P<0.05). The content of N in leaves decreased significantly by 4.22%, and the content of K in leaves and stems decreased significantly by 18.47% and 33.25% (P<0.05). There was no significant difference in C content among leaves, stems and roots. The contents of medium and trace elements in the leaves of C. Lacryma-jobi L. tended to decrease: the contents of S, Cu, Zn and Ni decreased significantly (P<0.05), by 18.06%, 54.01%, 37.96% and 50.49%, respectively, but the contents of Mn, Cu, Zn and Ni in stems increased significantly (P<0.05) by 90.20%, 70.55%, 46.80% and 149.50%, respectively. The elevated CO₂ concentration promoted the transportation of Mg and S from root to stem and Zn and Mn from stem to leaf, and the application of nitrogen fertilizer promoted the transportation of Fe from stem to leaf. In conclusion, the elevated CO₂ concentration and nitrogen application could affect the absorption and selective transport of mineral ions in different organs of C. Lacryma-jobi L., so as to maintain the balance of nutrient elements in the plant. The results of this study provided scientific basis for further understanding the variation characteristics of demand for nutrients elements of C. Lacryma-jobi L. under the change of atmospheric environment in the future and the selection of fertilization strategies on it.