盐生植物角果碱蓬种子二型性对环境的适应策略

doi:10.3724/SP.J.1258.2012.00781

摘要/Abstract

摘要：

角果碱蓬(Suaeda corniculata)是藜科一年生盐生植物, 在我国分布于北方盐碱滩涂和盐碱荒漠地区。角果碱蓬具有棕色和黑色两种异型体种子(简称棕色和黑色种子)。对采自内蒙古鄂托克前旗盐渍化生境的角果碱蓬二型种子的形态、休眠和萌发特性开展对比研究, 测定了二型种子休眠和萌发行为对温度、光照和盐分(NaCl)的响应, 以揭示盐生植物异型种子对温带盐漠生境的适应对策。结果表明: (1)二型性种子在大小、种皮特性和结实比例方面有显著差异。与黑色种子相比, 棕色种子个体较大, 种皮透水性强。黑色种子与棕色种子的结实比例约为5.6 : 1。(2)新成熟的棕色种子的萌发对各温度梯度和光照条件不敏感, 萌发率较高(84%-100%); 而新成熟的黑色种子萌发率较低(8%-78%), 萌发对光照敏感。(3)黑色种子具有浅度生理休眠, 种皮划破、赤霉素处理和低温层积均可有效地提高种子的萌发率。(4)二型种子萌发对土壤盐分的胁迫具有不同的响应。与黑色种子相比, 棕色种子对盐分胁迫不敏感, 在较高的盐分浓度下仍有较高的萌发率, 低温层积处理能够降低黑色种子对盐胁迫的敏感性, 有效地提高种子的初始萌发率、萌发恢复率和最终萌发率。角果碱蓬二型种子不同的形态、休眠和萌发特性, 提高了该物种在高度异质性生境中的适合度, 对种群成功地适应温带盐漠环境具有重要的意义。

关键词: 盐生植物, 盐生环境, 种子二型性, 种子萌发, 种子生理休眠, 角果碱蓬

Abstract:

Aims Suaeda corniculata (Chenopodiaceae) is an annual halophyte in salt marshes and saline deserts of northern China. It produces two distinct types of seeds (brown and black). The primary aims of our study were to compare the morphology, dormancy and germination characteristics of dimorphic seeds of S. corniculata in order to elucidate adaptive strategies of the desert halophyte in stressful saline habitat.
Methods Seeds were collected in saline habitats in Otog, Nei Mongol. The dimorphic seeds were incubated in different temperature regimes, light and salinity (NaCl) conditions to determine their germination responses. The effects of cold stratification and seed coat scarification on dormancy breaking of black seeds were also tested.
Important findings Dimorphic seeds were different in seed mass and testa morphology. Brown seeds were bigger and more permeable to water than black seeds. Seed ratio was 5.6 : 1 (black seeds : brown seeds). Freshly matured brown seeds had a high germination percentage (84%-100%) in all temperature regimes and under either light or dark conditions. By contrast, black seeds had a lower germination percentage (8%-78%) than brown seeds in all temperature regimes, and germination was increased in light. Seed coat scarification, GA₃ treatments and cold stratification significantly increased the germination of black seeds, suggesting that black seeds had non-deep physiological dormancy. Responses of dimorphic seeds to saline stress were different. Brown seeds were more salt-tolerant than black seeds and germinated at a high germination percentage in high salt concentrations. Cold stratification reduced the sensitivity of black seeds to salt stress and increased the initial germination percentage, recovery and final germination in salt solutions. The differences in morphology, dormancy and germination characteristics between dimorphic seeds of S. corniculata increased the species’ fitness to heterogeneous habitats and formed an ecological adaptive strategy that may allow S. corniculata to successfully adapt to the harsh desert habitat.

Key words: desert halophyte, saline habitat, seed dimorphism, seed germination, seed physiological dormancy, Suaeda corniculata

杨帆, 曹德昌, 杨学军, 高瑞如, 黄振英. 盐生植物角果碱蓬种子二型性对环境的适应策略. 植物生态学报, 2012, 36(8): 781-790. DOI: 10.3724/SP.J.1258.2012.00781

YANG Fan, CAO De-Chang, YANG Xue-Jun, GAO Rui-Ru, HUANG Zhen-Ying. Adaptive strategies of dimorphic seeds of the desert halophyte Suaeda corniculata in saline habitat. Chinese Journal of Plant Ecology, 2012, 36(8): 781-790. DOI: 10.3724/SP.J.1258.2012.00781

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https://www.plant-ecology.com/CN/Y2012/V36/I8/781

图/表 8

表1 1991-2009年角果碱蓬生境各月份平均最高、最低气温(℃)

Table 1 Mean minimum and maximum air temperatures in habitat of Suaeda corniculata from 1991 to 2009 (°C)

月份 Month	1月 Jan.	2月 Feb.	3月 Mar.	4月 Apr.	5月 May	6月 Jun.	7月 Jul.	8月 Aug.	9月 Sept.	10月 Oct.	11月 Nov.	12月 Dec.
最高气温 Maximum air temperature	-0.4	4.3	10.6	18.2	23.8	28.2	29.6	27.6	22.6	16.2	8.6	1.5
最低气温 Minimum air temperature	-16.4	-11.8	-4.3	2.7	9.0	13.8	16.5	14.8	9.0	1.4	-6.8	-14.1

图1 2010年生长季角果碱蓬生境平均气温、降水量和土壤中可溶性盐的动态变化(平均值±标准误差)。

Fig. 1 Dynamics of mean air temperature, precipitation and soluble salt content of soil in habitat of Suaeda corniculata during growing season in 2010 (mean ± SE).

表2 角果碱蓬二型种子形态特征、千粒重、数量比例(平均值±标准误差)

Table 2 Morphological characteristics, mass of 1000 seeds and seed ratio of dimorphic seeds of Suaeda corniculata (mean ± SE)

种子类型 Seed type	种皮特征 Testa characteristics	种子直径 Seed diameter (mm)	千粒重 Mass of 1000 seeds (mg)	黑色种子数:棕色种子数 Ratio of black seed to brown seed
棕色种子 Brown seed	膜质, 柔软, 无光泽 Membranous, soft and lusterless	1.07 ± 0.10^a	315.78 ± 1.75^a	5.60 ± 0.91
黑色种子 Black seed	角质, 硬脆, 有光泽 Keratose, hard, brittle and glossy	0.95 ± 0.08^b	240.35 ± 3.86^b	5.60 ± 0.91

图2 20-25 ℃气温、45%-50%相对湿度下角果碱蓬二型种子吸水曲线(平均值±标准误差)。G, 萌发时间点。

Fig. 2 Imbibition curves for dimorphic seeds of Suaeda corniculata at 20-25 °C air temperature and 45%-50% relative humidity (mean ± SE). G, germination time point.

图3 温度和光照对新成熟的角果碱蓬二型种子萌发率的影响(平均值±标准误差)。不同的大写字母表示同一类型的种子在相同光照条件、不同温度处理之间的萌发率差异显著; 不同的小写字母表示同一类型种子在相同温度、不同光照处理之间的萌发率差异显著(5%水平)。

Fig. 3 Effects of light and temperature on the germination of freshly matured dimorphic seeds of Suaeda corniculata (mean ± SE). Different capital letters indicate significant differences in germination of the same seed type among different temperatures under the same light condition, and different lowercase letters indicate significant differences in germination of the same seed type among different light conditions with the same temperature (5% level).

图4 20-25 ℃气温、45%-50%相对湿度下种皮处理(A)和赤霉素(GA3)处理(B)对角果碱蓬黑色种子萌发率的影响(平均值±标准误差)。不同的小写字母表示各个GA3浓度处理下的种子萌发率差异显著(5%水平)。

Fig. 4 Effect of testa treatment (A) and GA3 treatment (B) on germination of black seed of Suaeda corniculata at 20-25 °C and 45%-50% relative humidity (mean ± SE). Different lowercase letters indicate significant differences across all concentrations of GA3 (5% level).

图5 经过0-8周低温层积的角果碱蓬黑色种子在不同温度、光照或黑暗条件下的萌发率(平均值±标准误差)。不同的大写字母表示在相同的光照和低温层积时间, 不同温度处理之间的萌发率差异显著; 不同的小写字母表示相同温度和光照条件下, 不同的低温层积时间处理之间的萌发率差异显著(5%水平)。

Fig. 5 Germination of black seed of Suaeda corniculata at different temperatures in light or darkness after 0-8 weeks of cold stratification (mean ± SE). Different capital letters indicate significant differences in germination among different temperatures under the same light condition and cold stratification time, and different lowercase letters indicate significant differences in germination among different cold stratification time under the same temperature and light condition (5% level).

表3 NaCl对角果碱蓬二型种子萌发和恢复萌发率的影响

Table 3 Effect of NaCl on germination and germination recovery of dimorphic seeds of Suaeda corniculata

	盐度 Salinity (mol·L^-1)	初始萌发率 Initial germination (%, mean ± SE)	萌发恢复率 Germination recovery percentage (%, mean ± SE)	最终萌发率 Final germination (%, mean ± SE)	有生活力的种子 Viable seed (%, mean ± SE)	有生活力但未萌发的种子 Viable ungerminated seed (%, mean ± SE)
新成熟的黑色种子 Freshly matured black seed	0.0	58 ± 2^a	0^c	58 ± 2^a	100^a	42 ± 2^c
	0.1	16 ± 2^b	7 ± 3^b	22 ± 4^bc	100^a	78 ± 4^ab
	0.2	2 ± 2^c	7 ± 2^b	9 ± 2^c	100^a	91 ± 2^a
	0.5	1 ± 1^c	27 ± 3^a	28 ± 3^b	100^a	72 ± 3^b
	0.8	0^c	20 ± 2^ab	20 ± 2^bc	100^a	80 ± 2^ab
	1.0	0^c	32 ± 8^a	32 ± 8^b	100^a	68 ± 8^b
8周低温层积的黑色种子 Black seed after 8 weeks cold stratification	0.0	95 ± 3^a	0^c	95 ± 3^a	100^a	5 ± 3^b
	0.1	42 ± 11^b	0^c	42 ± 11^b	100^a	58 ± 11^a
	0.2	33 ± 5^bc	10 ± 3^b	40 ± 3^b	100^a	60 ± 3^a
	0.5	15 ± 6^cd	37 ± 10^a	45 ± 12^b	100^a	55 ± 12^a
	0.8	0^d	24 ±3^ab	24 ± 3^b	100^a	76 ± 3^a
	1.0	0^d	33 ± 5^a	33 ± 5^b	100^a	67 ± 5^a
新成熟的棕色种子 Freshly matured brown seed	0.0	100^a	--	100^a	100^a	0^b
	0.1	100^a	--	100^a	100^a	0^b
	0.2	100^a	--	100^a	100^a	0^b
	0.5	76 ± 7^b	96 ± 23^a	98 ± 1^a	100^a	1 ± 1^b
	0.8	42 ± 4^c	93 ± 1^a	96 ± 1^b	100^a	4 ± 1^a
	1.0	12 ± 2^d	92 ± 2^a	93 ± 2^b	100^a	7 ± 2^a

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