Effects of nitrogen and water addition on seed functional traits of Artemisia ordosica

doi:10.17521/cjpe.2024.0047

Abstract

Abstract:

Aims Seed traits are of great significance for clarifying plant population reproduction and regeneration strategies. Exploring responses of Artemisia ordosica seed traits to nitrogen and water addition can improve our understanding of desert plant community succession in the context of global change.

Methods The study was conducted based on a 8-year field water and nitrogen control experiment (2015-2022) in Mu Us Desert. A full factor interaction experiment of ambient precipitation, 20% water increase, 40% water increase and 0, 20, 60 kg N·hm⁻²·a⁻¹ were carried out to determine the morphological, physiological, chemical and germination traits of A. ordosica seed. Seed germination traits under each treatment at two temperatures (25 °C/15 °C and 20 °C /10 °C) were explored by using the petri dish germination experiment and calculating the germination indexes by observing the number of seedling emergence.

Important findings (1) Nitrogen and water addition, as well as their interactions, significantly influenced A. ordosica seed morphological traits, including seed mass, length, width, curvature, volume, form coefficient and other traits. Water addition resulted in smaller seeds while nitrogen alone led to larger seeds. However, 20% water increase mitigated the effect of nitrogen increase on seed size. Conversely, with a 40% water increase, nitrogen addition caused smaller seeds. (2) Germination percentage was higher at normal temperature (25 °C /15 °C) than that at low temperature conditions (20 °C /10 °C). At low temperature, seed germination traits were more affected by water and nitrogen addition experienced by parental organisms, and when only adding 20% and 40% water, A. ordosica had higher germination percentage. (3) Under the treatments of water and nitrogen addition, the morphological traits such as seed length, width, quality jointly regulated function of dispersal and establishment while form coefficient, 2 h water absorption, germination percentage and germination speed jointly regulated ecological function of germination timing. Adding water or nitrogen alone tent to the variation of only one function (seed dispersal and seedling establishment or seed germination) of A. ordosica seeds, while simultaneous addition of water and nitrogen led to the variation of both functions of A. ordosica seeds. These findings demonstrate that populations of A. ordosica possessed a great adaptability in response to global climate change by altering their functional strategies of seed dispersal, seedling establishment and seed germination.

Key words: nitrogen deposition, increased precipitation, Artemisia ordosica, seed traits, germination, reproduction

MA Bin, SHE Wei-Wei, QIN Huan, XUAN Rui-Zhi, SONG Chun-Yang, YUAN Xin-Yue, MIAO Chun, LIU Liang, FENG Wei, QIN Shu-Gao, ZHANG Yu-Qing. Effects of nitrogen and water addition on seed functional traits of Artemisia ordosica[J]. Chin J Plant Ecol, 2024, 48(12): 1637-1649.

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URL: https://www.plant-ecology.com/EN/10.17521/cjpe.2024.0047

https://www.plant-ecology.com/EN/Y2024/V48/I12/1637

Figures/Tables 8

Table 1 Effects of nitrogen and water addition on seed traits of Artemisia ordosica by two-factor ANOVAs (F value)

处理 Treatment	种子形态性状 Seed morphological trait
处理 Treatment	质量 Mass	长度 Length		宽度 Width		曲率 Curvature	体积 Volume	表面积 Surface area		宽长比 Width:length		形状系数 FC
氮添加 Nitrogen addition (N)	19.11^***	1.60^*		18.34^***		0.51	25.50^***	21.60^***		24.90^***		6.24^**
水添加 Water addition (W)	36.63^***	190.41^***		148.70^***		2.26^*	150.20^***	313.50^***		9.82^**		10.71^***
N × W	5.41^**	36.19^***		18.36^***		3.23^*	16.10^***	21.87^***		60.60^***		30.09^***
处理 Treatment	种子生理、化学性状 Seed physiological and chemical traits
处理 Treatment	0.5 h吸水率 0.5 ab (%)		1 h吸水率 1 ab (%)		2 h吸水率 2 ab (%)		碳含量 C content (%)		氮含量 N content (%)		碳氮比 C:N
氮添加 Nitrogen addition (N)	3.58^**		1.23		2.70^*		37.81^***		25.22^***		15.07^***
水添加 Water addition (W)	2.80^*		1.96		7.73^***		19.57^***		8.52^***		13.94^***
N × W	0.69		3.99^**		5.09^***		94.30^***		6.57^***		50.53^***

Fig. 1 Changes of seed morphological traits of Artemisia ordosica under different nitrogen and water additions. N0, no nitrogen addition; N1, nitrogen addition of 20 kg·hm-2·a-1; N2, nitrogen addition of 60 kg·hm-2·a-1. W0, no water addition; W1, 20% water addition; W2, 40% water addition. 0.5 ab, 0.5-hour water absorption of seeds; 1 ab, 1-hour water absorption of seeds; 2 ab, 2-hour water absorption of seeds; C, seed carbon content; Cur, seed curvature; FC, seed form coefficient; L, seed length; m, seed mass; N, seed nitrogen content; SA, seed surface area; V, seed volume; W, seed width.

Table 2 Two-factor analyses of variance (F value) of seed germination traits of Artemisia ordosica in response to nitrogen and water addition at two germination temperature treatments

萌发指标 Germination index	25 ℃/15 ℃			20 ℃/10 ℃
萌发指标 Germination index	氮添加 Nitrogen addition (N)	水添加 Water addition (W)	N × W	氮添加 Nitrogen addition (N)	水添加 Water addition (W)	N × W
幼苗高度 Seedling height	7.23^**	4.82^*	3.26^*	2.11	1.01	10.16^***
萌发指数 Germination index	2.16	1.31	5.02^**	27.50^***	39.11^***	16.67^***
活力指数 Vigor index	6.36^**	0.16	6.24^**	14.42^***	26.38^***	7.60^***
萌发速率 Germination speed	2.46	0.29	2.20	20.46^***	37.67^***	17.15^***
萌发率 Germination percentage	3.77^*	13.46^***	9.83^***	32.81^***	17.12^***	4.39
萌发势 Germination energy	0.42	0.49	2.41	42.42^***	40.88^***	34.42^***

Fig. 2 Daily cumulative number of Artemisia ordosica seedling emergence under two germination temperature treatments (mean ± SE). A, 20 °C/10 °C. B, 25 °C /15 °C. N0, no nitrogen addition; N1, nitrogen addition of 20 kg·hm-2·a-1; N2, nitrogen addition of 60 kg·hm-2·a-1. W0, no water addition; W1, 20% water addition; W2, 40% water addition.

Fig. 3 Effects of water and nitrogen addition on seed germination percentage (GP) (A, B) and germination energy (GE) (C, D) of Artemisia ordosica (mean ± SE). A, C, Germination temperature of 25 °C /15 °C. B, D, Germination temperature of 20 °C /10 °C. N0, no nitrogen addition; N1, nitrogen addition of 20 kg·hm-2·a-1; N2, nitrogen addition of 60 kg·hm-2·a-1. W0, no water addition; W1, 20% water addition; W2, 40% water addition.

Fig. 4 Correlation analyses among seed functional traits of Artemisia ordosica. A, Correlation map of germination traits at normal temperature with other traits. B, Correlation map of germination traits at low temperature with other traits. 0.5 ab, 0.5-hour water absorption of seeds; 1 ab, 1-hour water absorption of seeds; 2 ab, 2-hour water absorption; C, seed carbon content; C:N, ratio of seed carbon and nitrogen content; Cur, seed curvature; FC, seed form coefficient; GE, seed germination energy at normal temperature; GP, seed germination percentage at low temperature; L, seed length; m, seed mass; N, seed nitrogen content; PA, seed project area; S, seed germination speed at low temperature; SA, seed surface area; V, seed volume; VI, seed vigor index at normal temperature; W, seed width; W:L, ratio of seed width to length.

Table 3 Results of principal component (PC) analysis of seed traits of Artemisia ordosica

性状 Trait	对PC1的贡献度 Contribution to PC1 (%)	对PC2的贡献度 Contribution to PC2 (%)	对PC3的贡献度 Contribution to PC3 (%)	PC1的坐标值 Coordinate values in PC1	PC2的坐标值 Coordinate values in PC2	PC2的坐标值 Coordinate values in PC2
GP	19.62	0.31	0.61	0.87	0.08	0.08
S	12.82	0.98	29.46	0.71	-0.15	0.56
VI	12.51	5.80	20.92	0.70	-0.36	0.47
L	9.66	22.25	0.89	0.61	0.71	-0.10
N	6.74	13.22	0.08	0.51	-0.55	-0.03
m	0.16	28.07	1.08	0.08	0.80	0.11
Cur	0.63	23.22	1.82	-0.16	-0.73	-0.14
1 ab	3.85	5.34	21.23	-0.39	0.35	0.48
FC	16.97	0.03	6.90	-0.81	0.02	0.27
2 ab	17.05	0.78	17.02	-0.81	-0.13	0.43
方差占比 Variance percent (%)				38.86	22.73	10.77
累计方差占比 Cumulative variance percent (%)				38.86	61.59	72.36

Fig. 5 Principal component (PC) analysis of the effects of nitrogen and water addition on seed traits and germination traits of Artemisia ordosica. A, Seed traits load of A. ordosica. B, Response of seed traits of A. ordosica to nitrogen increase. C, Response of seed traits of A. ordosica to water increase. 1 ab, 1-hour water absorption of seeds; 2 ab, 2-hour water absorption of seeds; Cur, seed curvature; GP, seed germination percentage at normal temperature; L, seed length; m, seed mass; N, seed nitrogen content; S, seed germination speed at normal temperature; VI, seed vigor index at normal temperature. N0, no nitrogen addition; N1, nitrogen addition of 20 kg·hm-2·a-1; N2, nitrogen addition of 60 kg·hm-2·a-1. W0, no water addition; W1, 20% water addition; W2, 40% water addition.

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