氮添加对红锥不同序级细根形态和化学性状的影响

doi:10.17521/cjpe.2023.0069

摘要/Abstract

摘要：

细根作为植物养分获取和能量运输的重要器官, 是根系中最活跃和最敏感的部分, 其功能属性沿环境梯度的变化规律能够反映植物对资源的利用策略及对环境变化的适应性。该研究旨在解析不同氮(N)添加水平对红锥(Castanopsis hystrix)细根形态、化学性状的影响, 探究红锥细根对短期N添加的可塑性, 为阐明和预测全球气候变化背景下植物根系生理功能变化提供理论支撑。2020年1月, 在红锥林内设置4个N添加水平样地: 对照(CK, 0 kg·hm^-2·a^-1)、低氮(LN, 50 kg·hm^-2·a^-1)、中氮(MN, 100 kg·hm^-2·a^-1)、高氮(HN, 150 kg·hm^-2·a^-1), 每个处理3个重复。利用挖掘法挖取红锥根系, 测定其1-5级根在不同N添加水平处理下细根比根长(SRL)、比表面积(SRA)、组织密度(RTD)、平均直径(RD)和化学计量的变化。结果表明, 与CK相比, MN、HN显著降低了土壤pH, HN显著增加了土壤硝态氮(NO₃^--N)和全磷(P)含量; N添加显著增加了1级细根的碳(C)含量; HN显著增加了2级细根C含量; MN和HN显著增加了1、2级细根的N含量, 但显著降低了2级细根的C:N; 不同N添加水平下细根的SRL、SRA、RTD和RD均无显著差异。因此短期N添加主要影响细根的元素含量及其化学计量比, 而未显著影响细根的形态性状, 这些结果将有助于理解南亚热带地区森林地下养分循环以及碳固存对全球环境变化的响应。

关键词: 根序, 氮添加, 细根, 形态性状, 可塑性

Abstract:

Aims As an important organ for plant nutrient acquisition and energy transport, fine roots are the most active and sensitive part of the root system. Their functional traits change along the environmental gradient, which can reflect plant resource acquisition strategies and adaptability to environmental changes. The purpose of this study was to analyze the effects of different nitrogen (N) addition levels on the morphological and chemical traits of the fine roots of Castanopsis hystrix, explore the plasticity of the fine roots of the species to short-term N addition, and provide theoretical support for clarifying and predicting the changes of root physiological function under global climate change.

Methods In January 2020, four treatments with different N addition levels were set up in the C. hystrix plantation, which were the control (CK, 0 kg·hm^-2·a^-1), low N treatment (LN, 50 kg·hm^-2·a^-1), medium N treatment (MN, 100 kg·hm^-2·a^-1) and high N treatment (HN, 150 kg·hm^-2·a^-1), with three replicates per treatment. Fine roots of C. hystrix were dug out by the excavation method, and traits of the 1st to 5th order fine roots in different N addition treatments were determined, including specific root length, specific root area, root tissue density, average root diameter and stoichiometry.

Important findings The results showed that, compared with the CK treatment, MN and HN treatments significantly reduced soil pH, HN treatment significantly increased soil NO₃^--N and total phosphorus contents. Nitrogen addition significantly increased the content of carbon (C) in the 1st order fine root. HN treatment significantly increased the C content of the 2nd order fine root. MN and HN treatments significantly increased the N content of the 1st and 2nd order fine root, and significantly decreased the C:N of the 2nd order fine root. There were no significant differences in specific root length, specific root surface area, root tissue density and average root diameter of fine roots under different N addition levels. Taken together, these results showed that short-term N addition mainly affected the element content and stoichiometric ratio of fine roots, but had no significant effect on the morphological traits of fine roots in the C. hystrix plantation. This finding will help to understand the response of forest nutrient cycling and C sequestration to global environmental changes in the southern subtropical region.

Key words: root order, nitrogen addition, fine root, morphological trait, plastic

舒韦维, 杨坤, 马俊旭, 闵惠琳, 陈琳, 刘士玲, 黄日逸, 明安刚, 明财道, 田祖为. 氮添加对红锥不同序级细根形态和化学性状的影响. 植物生态学报, 2024, 48(1): 103-112. DOI: 10.17521/cjpe.2023.0069

SHU Wei-Wei, YANG Kun, MA Jun-Xu, MIN Hui-Lin, CHEN Lin, LIU Shi-Ling, HUANG Ri-Yi, MING An-Gang, MING Cai-Dao, TIAN Zu-Wei. Effects of nitrogen addition on the morphological and chemical traits of fine roots with different orders of Castanopsis hystrix. Chinese Journal of Plant Ecology, 2024, 48(1): 103-112. DOI: 10.17521/cjpe.2023.0069

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链接本文: https://www.plant-ecology.com/CN/10.17521/cjpe.2023.0069

https://www.plant-ecology.com/CN/Y2024/V48/I1/103

图/表 4

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处理 Treatment	土壤性质 Soil property
处理 Treatment	pH	铵态氮含量 NH₄⁺-N content (mg·kg^-1)	硝态氮含量 NO₃^--N content (mg·kg^-1)	有机碳含量 Organic carbon content (g·kg^-1)	全磷含量 Total phosphorus content (g·kg^-1)	全氮含量 Total N content (g·kg^-1)
对照 Control (CK)	4.87 ± 0.06^a	4.04 ± 0.26^a	0.59 ± 0.15^b	13.77 ± 1.08^a	0.27 ± 0.06^b	0.79 ± 0.07^a
低氮 Low N (LN)	4.72 ± 0.04^ab	4.91 ± 0.27^a	1.07 ± 0.18^ab	15.13 ± 0.54^a	0.31 ± 0.01^ab	1.02 ± 0.14^a
中氮 Medium N (MN)	4.58 ± 0.04^bc	4.34 ± 0.27^a	1.29 ± 0.63^ab	16.14 ± 0.67^a	0.37 ± 0.01^ab	1.10 ± 0.15^a
高氮 High N (HN)	4.42 ± 0.02^c	4.32 ± 0.47^a	1.99 ± 0.63^a	16.53 ± 0.96^a	0.43 ± 0.01^a	1.23 ± 0.11^a

处理 Treatment	土壤性质 Soil property
处理 Treatment	pH	铵态氮含量 NH₄⁺-N content (mg·kg^-1)	硝态氮含量 NO₃^--N content (mg·kg^-1)	有机碳含量 Organic carbon content (g·kg^-1)	全磷含量 Total phosphorus content (g·kg^-1)	全氮含量 Total N content (g·kg^-1)
对照 Control (CK)	4.87 ± 0.06^a	4.04 ± 0.26^a	0.59 ± 0.15^b	13.77 ± 1.08^a	0.27 ± 0.06^b	0.79 ± 0.07^a
低氮 Low N (LN)	4.72 ± 0.04^ab	4.91 ± 0.27^a	1.07 ± 0.18^ab	15.13 ± 0.54^a	0.31 ± 0.01^ab	1.02 ± 0.14^a
中氮 Medium N (MN)	4.58 ± 0.04^bc	4.34 ± 0.27^a	1.29 ± 0.63^ab	16.14 ± 0.67^a	0.37 ± 0.01^ab	1.10 ± 0.15^a
高氮 High N (HN)	4.42 ± 0.02^c	4.32 ± 0.47^a	1.99 ± 0.63^a	16.53 ± 0.96^a	0.43 ± 0.01^a	1.23 ± 0.11^a

指标 Index	p
指标 Index	氮添加 N addition	序级 Order	氮添加 × 序级 N addition × order
比根长 Specific root length	0.063	0.781	0.003^**
比表面积 Specific root area	0.051	0.797	0.006^**
组织密度 Root tissue density	0.015^*	0.134	0.719
平均直径 Average root diameter	0.732	<0.001^***	0.977
碳(C)含量 Carbon (C) content	<0.001^***	<0.001^***	0.248
氮含量 N content	<0.001^***	<0.001^***	0.026^*
磷(P)含量 Phosphorus (P) content	0.009^**	<0.001^***	0.909
碳氮比 C:N	0.004^**	<0.001^***	0.998
氮磷比 N:P	0.169	0.005^**	0.929
碳磷比 C:P	0.136	<0.001^***	0.893

指标 Index	p
指标 Index	氮添加 N addition	序级 Order	氮添加 × 序级 N addition × order
比根长 Specific root length	0.063	0.781	0.003^**
比表面积 Specific root area	0.051	0.797	0.006^**
组织密度 Root tissue density	0.015^*	0.134	0.719
平均直径 Average root diameter	0.732	<0.001^***	0.977
碳(C)含量 Carbon (C) content	<0.001^***	<0.001^***	0.248
氮含量 N content	<0.001^***	<0.001^***	0.026^*
磷(P)含量 Phosphorus (P) content	0.009^**	<0.001^***	0.909
碳氮比 C:N	0.004^**	<0.001^***	0.998
氮磷比 N:P	0.169	0.005^**	0.929
碳磷比 C:P	0.136	<0.001^***	0.893

处理 Treatment	序级 Order	细根形态特征 Fine root morphological traits
处理 Treatment	序级 Order	SRL	SRA	RTD	RD
对照 CK	1	2 687.12 ± 306.89^a	325.07 ± 51.88^a	0.24 ± 0.05^a	0.42 ± 0.04^c
	2	984.39 ± 60.56^b	178.76 ± 12.06^b	0.31 ± 0.03^a	0.49 ± 0.03^bc
	3	553.05 ± 72.12^b	139.36 ± 23.19^b	0.29 ± 0.02^a	0.61 ± 0.03^bc
	4	404.58 ± 71.53^b	106.87 ± 21.23^b	0.31 ± 0.01^a	0.72 ± 0.02^b
	5	183.75 ± 10.86^b	83.41 ± 6.19^b	0.28 ± 0.02^a	1.06 ± 0.10^a
低氮 LN	1	3 402.35 ± 311.18^a	428.67 ± 48.68^a	0.17 ± 0.05^a	0.47 ± 0.09^b
	2	1 325.47 ± 204.56^b	227.36 ± 31.60^b	0.26 ± 0.03^a	0.52 ± 0.03^ab
	3	692.32 ± 167.10^b	161.37 ± 18.39^b	0.25 ± 0.02^a	0.66 ± 0.05^ab
	4	443.18 ± 69.86^b	129.94 ± 12.82^b	0.25 ± 0.01^a	0.73 ± 0.06^ab
	5	260.02 ± 57.63^b	99.12 ± 10.71^b	0.25 ± 0.01^a	1.00 ± 0.23^a
中氮 MN	1	3 080.89 ± 332.79^a	373.67 ± 47.62^a	0.20 ± 0.05^a	0.44 ± 0.05^b
	2	1 036.45 ± 130.02^b	179.83 ± 12.17^b	0.31 ± 0.02^a	0.51 ± 0.03^b
	3	583.91 ± 145.00^b	140.59 ± 19.12^b	0.29 ± 0.04^a	0.61 ± 0.04^ab
	4	235.50 ± 66.09^b	118.05 ± 8.39^b	0.28 ± 0.02^a	0.66 ± 0.04^ab
	5	202.32 ± 26.35^b	80.57 ± 2.00^b	0.30 ± 0.07^a	0.96 ± 0.19^a
高氮 HN	1	2 919.41 ± 579.32^a	311.16 ± 67.99^a	0.27 ± 0.07^a	0.38 ± 0.03^c
	2	1 180.52 ± 304.85^b	187.42 ± 32.31^b	0.33 ± 0.04^a	0.48 ± 0.04^c
	3	578.05 ± 144.11^b	139.59 ± 23.87^b	0.31 ± 0.04^a	0.66 ± 0.04^bc
	4	343.21 ± 36.54^b	115.32 ± 8.62^b	0.26 ± 0.02^a	0.82 ± 0.04^b
	5	166.01 ± 49.67^b	75.43 ± 14.07^b	0.29 ± 0.02^a	1.15 ± 0.13^a