美国海滨桤木和薄叶桤木水分生理特性的比较

doi:10.3724/SP.J.1258.2011.00073

摘要/Abstract

摘要：

采取盆栽、人工控水的方式, 研究并比较了美国本土海滨桤木(Alnus maritima)和薄叶桤木(A. incana)的气孔导度(G_s)、叶片水势(ψ_leaf)以及渗透调节能力对土壤水分条件的响应, 以探讨引起两种桤木生态分布差异巨大的生理生态原因。结果表明: 1)正常水分条件下, 海滨桤木的G_s低于薄叶桤木, 其与大气温度、相对湿度和水蒸气亏缺等气象因子的相关性低于薄叶桤木; 干旱胁迫下, 海滨桤木的G_s对其自身ψ_leaf下降信号的敏感度低于薄叶桤木; 复水后, 其G_s恢复更为缓慢。2)正常水分条件下, 海滨桤木的ψ_leaf高于薄叶桤木, 且引起气孔关闭的ψ_leaf临界值较高; 干旱胁迫下, 海滨桤木的ψ_leaf下降幅度高于薄叶桤木。3)正常水分条件下, 海滨桤木和薄叶桤木的渗透调节能力无显著差异; 干旱胁迫下, 尽管两种桤木均表现出饱和状态渗透势(ψ_s^sat)下降、膨压与水势关系的最大变化率降低、初始失膨点渗透势(ψ_s^tlp)增加、细胞渗透调节能力范围(ψ_s^sat-ψ_s^tlp, Dψ_s)减小的趋势, 但与薄叶桤木相比, 海滨桤木的ψ_s^tlp较高, Dψ_s较小。从以上生理生态指标可以看出, 较高的叶片水势、较低的气孔调节能力、干旱下较低的渗透调节能力是造成海滨桤木分布范围狭小的重要原因。

关键词: 桤木, 生态分布, 叶片水势, 渗透调节, 气孔导度

Abstract:

Aims Our goal was to compare basic physiological responses to water stress of Alnus maritima and A. incana in order to (a) explain why A. maritima occupies a small, patchy distribution in eastern U.S.A. while A. incana is broadly distributed and (b) further understand potential differences in adaptation to drought in these two species.
Methods We compared stomatal conductance (G_s), leaf water potential (ψ_leaf) and basic osmotic regulation in A. maritima and A. incana under artificial soil irrigation.
Important findings Alnus maritima kept a lower G_s and lower correlation coefficients with air temperature, vapor pressure deficit and relative humidity than A. incana under irrigation. During the dry-down period, A. maritima showed weaker ability to keep stomata open as influenced by the decrease of ψ_leaf. In the re-water experiment, G_s of A. maritima showed slower recovery than A. incana. Alnus maritima kept a higher ψ_leaf and also a higher threshold of ψ_leaf to close their stomata under well-watered conditions. The decline in ψ_leaf was larger under drought stress compared with A. incana. There was no significant difference in osmotic regulation between the two species under normal water conditions. However, under drought, both species showed: (a) a decrease in solute potential at full turgor (ψ_s^sat), (b) a decline of maximum variation rate of turgor pressure against solute potential, (c) an increase in solute potential at turgor loss point (ψ_s^tlp) and (d) a decrease in Dψ_s. The ψ_s^tlpof A. maritima was higher and Dψ_s was lower than in A. incana. These results indicated that the small, patchy distribution of A. maritima may partly be attributed to the lower sensitivity of leaf stomata, higher leaf water potential and decrease in ability to adjust osmotically under drought stress.

Key words: Alnus, ecological distribution, leaf water potential, osmotic regulation, stomatal conductance

李秀媛, 刘西平, Hang DUONG, Roger KJELGREN. 美国海滨桤木和薄叶桤木水分生理特性的比较. 植物生态学报, 2011, 35(1): 73-81. DOI: 10.3724/SP.J.1258.2011.00073

LI Xiu-Yuan, LIU Xi-Ping, Hang DUONG, Roger KJELGREN. Comparison of water-related physiological characteristics of Alnus maritima and A. incana growing in America. Chinese Journal of Plant Ecology, 2011, 35(1): 73-81. DOI: 10.3724/SP.J.1258.2011.00073

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https://www.plant-ecology.com/CN/Y2011/V35/I1/73

图/表 9

图1 正常水分条件下海滨桤木和薄叶桤木气孔导度(Gs) (A)和叶片水势(ψleaf) (B)的日变化。a、b表示相同时间下海滨桤木和薄叶桤木Gs或ψleaf的差异极显著(Duncan, p < 0.01)。

Fig. 1 Diurnal variation of stomotal conductance (Gs) (A) and leaf water potential (ψleaf ) (B) of Alnus maritima and A. incana under normal water condition. a and b indicate significance of Gs or ψleaf between A. maritima and A. incana at the same time at 0. 01 level by Duncan test.

图2 海滨桤木和薄叶桤木气孔导度和叶片水势的关系。

Fig. 2 Relationship between stomatal conductance (Gs) and leaf water potential (ψleaf) of Alnus maritima and A. incana.

表1 海滨桤木和薄叶桤木的气孔导度(Gs)与气象因子(水汽压亏缺、太阳辐射、空气温度和相对湿度)的相关系数

Table 1 Correlation coefficients between stomatal conductance (Gs) of Alnus maritima and A. incana and meteorological variables (vapor pressure deficit, solar radiation, air temperature and relative humidity)

	水汽压亏缺 Vapor pressure deificit	太阳辐射 Solar radiation	空气温度 Air temperature	相对湿度 Relative humidity
海滨桤木 Alnus maritima	-0.549^**	0.027	-0.560^**	0.501^**
薄叶桤木 A. incana	-0.695^**	0.096	-0.720^**	0.700^**

图3 水分胁迫下海滨桤木和薄叶桤木气孔导度(Gs)和叶片水势(ψleaf)的变化。A、B、C、D分别表示充分灌溉和干旱胁迫处理Gs上午测量值, 充分灌溉和干旱胁迫处理Gs下午测量值。E和F分别表示充分灌溉处理和干旱胁迫处理的ψleaf。a、b、c、d表示海滨桤木和薄叶桤木间的极显著差异(Duncan, p < 0.01)。

Fig. 3 Variation of stomatal conductance (Gs) and leaf water potential (ψleaf) of Alnus maritima and A. incana under drought stress treatments. A, B, C and D represent the Gs mid-morning value of well watered treatment, drought stress treatment, and the mid-afternoon Gs value of these two treatments, respectively. E and F represent the ψleaf values of well watered and drought stress treatments, respectively. a, b, c and d indicate the significance between A. maritima and A. incana at 0. 01 level by Duncan test.

表2 干旱胁迫下海滨桤木和薄叶桤木气孔导度(Gs)的下降百分比(1- Gs干旱胁迫处理/ Gs充分灌溉处理) (%)

Table 2 Decrease in percentage of stomatal conductance (Gs) under drought stress in Alnus maritima and A. incana (1- Gsdrought- stressed/ Gswell-watered) (%)

树种 Species	天数 Day
树种 Species	1	2	3	4	5	6
海滨桤木 Alnus maritima	14.01	24.11	26.34	41.00	61.25	72.41
薄叶桤木 A. incana	0.98	3.51	10.03	35.69	67.10	88.04

图4 干旱胁迫与充分灌溉处理下海滨桤木和薄叶桤木气孔导度比值(Gs drought stressed / Gs well watered)和叶片水势比值(ψleaf drought stressed / ψleaf well watered)的关系。——表示海滨桤木的线性回归线; 表示薄叶桤木线性回归线。

Fig. 4 Relationship between the water potential (ψleaf) ratio of drought stressed to well watered and the stomatal conductance (Gs) ratio of drought stressed to well watered for Alnus maritima and A. incana. —— and represent the regression lines of A. maritima and A. incana, respectively.

图5 复水过程中海滨桤木和薄叶桤木气孔导度的变化。A、B、C和D见图3。a、b、c和d表示同一天下海滨桤木和薄叶桤木Gs间的显著差异(Duncan, p < 0.05)。

Fig. 5 Changes in stomatal conductance (Gs) of Alnus maritima and A. incana after well-rewatered treatment. A, B, C and D see Fig. 3. a, b, c and d indicate significance between A. maritima and A. incana at the same day at 0.05 level by Duncan test.

表3 海滨桤木和薄叶桤木的渗透调节参数(MPa)

Table 3 Parameters of osmotic adjustment for Alnus maritima and A. incana (MPa)

处理 Treatment	饱和渗透势 Solute potential at full turgor ψ_s^sat	失膨点渗透势 Solute potential at turgor loss point ψ_s^tlp	渗透势调节范围 Dψ_s(ψ_s^sat-ψ_s^tlp)
海滨桤木-充分灌溉 Alnus maritime-well watered	-0.92^a	-1.29^a	0.38^a
海滨桤木-干旱胁迫 A. maritime-drought stress	-1.08^b	-1.11^c	0.03^c
薄叶桤木-充分灌溉 A. incana-well watered	-0.91^a	-1.35^a	0.44^a
薄叶桤木-干旱胁迫 A. incana-drought stress	-1.04^b	-1.27^b	0.24^b

表4 海滨桤木和薄叶桤木叶片水势(ψleaf)和膨压(ψp )直线斜率方程(k)

Table 4 The slopes (k) of linear equation between leaf water potential (ψleaf ) and turgor (ψp ) of Alnus maritima and A. incana

处理 Treatment	海滨桤木-充分灌溉 Alnus maritime-well watered	海滨桤木-干旱胁迫 A. maritime-drought stress	薄叶桤木-充分灌溉 A. incana-well watered	薄叶桤木-干旱胁迫 A. incana-drought stress
R²	0.996	0.997	0.998	0.997
k	0.864^a	0.793^b	0.768^b	0.685^b

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