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吸收营养物质是植物根系的主要生理功能。氮素吸收是植物体内氮代谢的第一步,也是最关键的一步。为了全面地认识亚高山针叶林在全球气候变化背景下对两种主要无机氮(NH_4~+和NO_3~–)吸收特点的变化,该研究以川西亚高山针叶林优势树种——云杉(Picea asperata)和岷江冷杉(Abies fargesii var.faxoniana)为材料,通过红外辐射加热器模拟增温,利用非损伤微测技术(non-invasive micromeasurement technology)研究了这两个树种吸收NH_4~+和NO_3~–特点的变化,同时还探究了NH_4~+和NO_3~–之间的相互作用对植物吸收这两种离子的影响。研究结果显示:在云杉根系中,NH_4~+和NO_3~–的最大吸收速率分别发生在距离根尖最顶端17–18 mm区域和17 mm处,而岷江冷杉对这两种离子的最大吸收速率分别发生在距离根尖顶端11 mm和11.5mm处。增温对云杉和岷江冷杉根系吸收NH_4~+和NO_3~–有促进作用。在增温条件下,NO_3~–能够促进云杉根系对NH_4~+的吸收,而NH_4~+则抑制了其对NO_3~–的吸收。无论是否增温,岷江冷杉对NH_4~+的吸收都不受NO_3~–的影响,而在增温条件下,NH_4~+会抑制岷江冷杉对NO_3~–的吸收。
Absorption of nutrients is the main physiological function of plant roots. Nitrogen absorption is the first step in nitrogen metabolism in plants and also the most crucial step. In order to comprehensively understand the changes of the absorption characteristics of two major inorganic nitrogen (NH_4 + and NO_3 -) in the sub-alpine coniferous forest in the context of global climate change, this study took the dominant species of sub-alpine coniferous forest (Picea asperata) and Abies fargesii var. Faxoniana were used as materials to simulate the warming by infrared radiation heaters. The non-invasive micromeasurement technology was used to study the effects of NH 4 + and NO_3 ~ - changes in the characteristics, but also explored the NH_4 ~ + and NO_3 ~ interaction between the two plants to absorb the impact of the ion. The results showed that the maximum absorption rates of NH_4 ~ + and NO_3 ~ in the roots of spruce occurred in the region of 17-18 mm from the top of the root tip and at 17 mm, respectively. However, the maximum absorption of these two ions The rates occurred at 11 mm and 11.5 mm from apical apex, respectively. Increasing temperature can promote the uptake of NH_4 ~ + and NO_3 ~ in roots of spruce and Abies. Under the condition of warming, NO_3 ~ - can promote the absorption of NH_4 ~ + in the root of spruce, while NH_4 ~ + inhibited the absorption of NO_3 ~ -. Absorption of NH_4 ~ + by Minjiang River fir was not affected by NO_3 ~ - regardless of warming or not, while NH_4 ~ + inhibited the absorption of NO_3 ~ - in Minjiang fir under increasing temperature.