Fine root morphology and growth in response to nitrogen addition through drip fertigation in a Populus × euramericana “Guariento” plantation over multiple years
- 12 Downloads
Nitrogen addition through drip fertigation to a poplar plantation ( Populus × euramericana “Guariento”) promoted fine root growth only in the early period. The relationship between root growth and soil N content was positive in the first 2 years, but became negative in the third year when the soil N availability had substantially increased.
Nitrogen (N) deficiency is common in forest soils, and N addition is sometimes applied in the case of intensive plantations. There is a need to better document the impact of N addition through the high-efficiency fertilization technique on fine root morphology and growth, given their importance for the uptake of nutrients and for tree growth.
We aimed to quantitatively investigate the responses of fine roots in morphology and growth to N addition through surface drip fertigation over multiple years in a Populus × euramericana “Guariento” plantation.
A field experiment that included four drip fertigation treatments with N addition levels (0, 60, 120, and 180 kg N ha−1 year−1) was conducted for three successive years. A coring method was used to sample soils and quantify the root morphological traits and soil N content along 0–60-cm profiles.
The root biomass density, length, surface area, specific length, and tissue density were significantly higher in the N addition treatments than those in the control after the first year, but the positive effect decreased in the second year. In the third year, root biomass in the N addition treatments was even lower by 11–39% than that in the control. The relationship between root growth and soil N content was also positive in the first 2 years and negative in the third year.
N addition promoted fine root growth mainly in the shallow soil and in the early period of experiment. The relationship between root growth and soil N content became negative in the third year when the soil N availability had substantially increased. It is suggested that fine roots adjust their growth and morphology in response to N availability varying along the soil profile and with the fertilization duration.
KeywordsNitrogen addition Fine root Root morphology Vertical distribution Drip fertigation Populus × euramericana “Guariento”
This research was jointly supported by the National Natural Science Foundation of China (31670625 and 31700557).
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
- Fitter AH, Stickland TR, Harvey ML, Wilson GW (1991) Architectural analysis of plant root systems 1. Architectural correlates of exploitation efficiency. New Phytol 118:375–382. https://doi.org/10.1111/j.1469-8137.1991.tb00018.x CrossRefGoogle Scholar
- Fort F, Cruz P, Catrice O, Delbrut A, Luzarreta M, Stroia C, Jouany C (2015) Root functional trait syndromes and plasticity drive the ability of grassland Fabaceae to tolerate water and phosphorus shortage. Environ Exp Bot 110:62–72. https://doi.org/10.1016/j.envexpbot.2014.09.007 CrossRefGoogle Scholar
- Ostertag R (2001) Effects of nitrogen and phosphorus availability on fine-root dynamics in Hawaiian montane forests. Ecology 82:485–499. https://doi.org/10.1890/0012-9658(2001)082[0485:EONAPA]2.0.CO;2Google Scholar
- Ostonen I, Helmisaari HS, Borken W, Tedersoo L, Mai K, Bahram M, Lindroos AJ, Nöjd P, Uri V, Merilä P (2011) Fine root foraging strategies in Norway spruce forests across a European climate gradient. Glob Chang Biol 17:3620–3632. https://doi.org/10.1111/j.1365-2486.2011.02501.x CrossRefGoogle Scholar
- Phoenix GK, Emmett BA, Britton AJ, Caporn SJM, Dise NB, Helliwell R, Jones L, Leake JR, Leith ID, Sheppard LJ (2012) Impacts of atmospheric nitrogen deposition: responses of multiple plant and soil parameters across contrasting ecosystems in long-term field experiments. Glob Chang Biol 18:1197–1215. https://doi.org/10.1111/j.1365-2486.2011.02590.x CrossRefGoogle Scholar
- Pregitzer KS, Hendrick RL, Fogel R (1993) The demography of fine roots in response to patches of water and nitrogen. New Phytol 125:575–580. https://doi.org/10.1111/j.1469-8137.1993.tb03905.x CrossRefGoogle Scholar
- Pregitzer KS, Zak DR, Curtis PS, Kubiske ME, Teeri JA, Vogel CS, Pregitzer BYKS, Zak R, Vogel S (1995) Atmospheric CO2, soil nitrogen and turnover of fine roots. New Phytol 129:579–585. https://doi.org/10.1111/j.1469-8137.1995.tb03025.x CrossRefGoogle Scholar
- Pregitzer KS, Zak DR, Maziasz J, Deforest J, Curtis PS, Lussenhop J (2000) Interactive effects of atmospheric CO2 and soil-N availability on fine roots of Populus tremuloides. Ecol Appl 10:18–33. https://doi.org/10.1890/1051-0761(2000)010[0018:IEOACA]2.0.CO;2Google Scholar
- Van Diepen LTA, Lilleskov EA, Pregitzer KS, Miller RM (2010) Simulated nitrogen deposition causes a decline of intra- and extraradical abundance of arbuscular mycorrhizal fungi and changes in microbial community structure in northern hardwood forests. Ecosys 13:683–695. https://doi.org/10.1007/s10021-010-9347-0 CrossRefGoogle Scholar
- Wang C, Han S, Zhou Y, Yan C, Cheng X, Zheng X, Li MH (2012) Responses of fine roots and soil N availability to short-term nitrogen fertilization in a broad-leaved Korean pine mixed forest in northeastern China. PLoS One 7:e31042. https://doi.org/10.1371/journal.pone.0031042 CrossRefPubMedPubMedCentralGoogle Scholar
- Wang Y, Xi B, Bloomberg M, Moltchanova E, Li G, Jia L (2015) Response of diameter growth, biomass allocation and N uptake to N fertigation in a triploid Populus tomentosa plantation in the North China plain: ontogenetic shift does not exclude plasticity. Eur J For Res 134:889–898. https://doi.org/10.1007/s10342-015-0897-8 CrossRefGoogle Scholar
- Xi B, Wang Y, Jia L, Bloomberg M, Li G, Di N (2013) Characteristics of fine root system and water uptake in a triploid Populus tomentosa plantation in the North China Plain: implications for irrigation water management. Agric Water Manag 117:83–92. https://doi.org/10.1016/j.agwat.2012.11.006 CrossRefGoogle Scholar