大麦种子对盐的发芽响应模型

doi:10.3724/SP.J.1258.2012.00849

摘要/Abstract

摘要：

为了明确盐对种子发芽影响的渗透效应和离子效应共同作用方式以及量化种子发芽对盐的响应, 以两个大麦(Hordeum vulgare)品种‘Cask’和‘County’为研究对象, 设置4个恒定温度(5、12、20和27 ℃)、5个等渗的NaCl和聚乙二醇(PEG)浓度梯度(-0.45、-0.88、-1.32、-1.76和-2.20 MPa, 蒸馏水作对照), 做常规发芽实验。结果显示: (1)两个品种在NaCl溶液中比在等渗的PEG溶液中发芽率高且发芽速度快; (2) NaCl和PEG分别作为渗透剂计算出的水势模型参数值差异很大, 说明水势模型不能用来描述种子发芽对盐的响应; (3)大麦种子在盐溶液中的发芽速率与盐浓度成显著的负相关直线关系, 因此我们修订了水势模型, 将修订后的模型命名为盐度模型, 用来量化盐对大麦种子发芽的影响。与水势模型计算出的发芽时间相比, 盐度模型计算出的50%种子发芽时间与大麦种子实际发芽时间更接近; (4)大麦种子在等渗的NaCl和PEG溶液中发芽速率差异随着水势降低, 先增加后降低。据此我们提出盐的渗透效应和离子效应共同作用于种子发芽的3种情况: 第一种在低盐条件下, 主要是渗透效应起负作用; 第二种情况在中盐条件下, 渗透效应和离子效应共同起作用, 离子效用的正作用强于渗透效应的负作用; 第三种情况在高盐条件下, 离子效应逐渐开始起离子毒害的负作用。

关键词: 大麦, 离子效应, 模型, 渗透效应, 盐, 种子发芽

Abstract:

Aims Salinization is a worldwide problem, and some researchers focus on the effect of salt on seed germination. The results are variable, and quantifying germination response to salt is significant. Furthermore, seed germination is affected by salinity, as a result of both osmotic and ion effects. How the two effects act together is unclear. Thus our objectives are to propose a model to accurately describe the effect of salt on seed germination and to clarify the role of the osmotic and the ion effect act under different salinities.
Methods Two varieties of barley (Hordeum vulgare) seeds (‘Cask’ and ‘County’) were cultured in five binate iso-osmotic polyethylene glycol (PEG) and NaCl solutions (-0.45, -0.88, -1.32, -1.76 and -2.20 MPa, distilled water as the control) at four constant temperatures of 5, 12, 20 and 27 °C. Germination time courses were recorded and germination rates (the reciprocal of germination time) were calculated. The hydrotime model and the new salinity model were used to calculate the parameters and test which was the better fit.
Important findings Results indicated that not only were seeds in saline conditions able to germinate at lower osmotic potentials than seeds germinating in an isotonic PEG-6000 solution, but that they were also able to do so faster. The hydrotime parameters of the NaCl treatments had great differences with the isotonic PEG treatments, which indicated the hydrotime model cannot describe salt effects on seed germination well. Barley seed germination rates in salt solutions were negatively linear with salinity. We proposed a salinity model to quantify germination response to salt. The germination time calculated from the salinity model approached the real data, compared to that calculated from the hydrotime model. Differences of germination rates in NaCl and the isotonic PEG treatments increased and then decreased with decreasing water potential. We suggest three situations of function mode by the osmotic and ion effects of salt. First, at low salinities the osmotic effect acts as the main negative role. Second, at medium salinities the two effects act together, with the positive ion effect stronger than the negative osmotic effect. Third, at high salinities the ion effect begins to harm the germination process.

Key words: barley (Hordeum vulgare), ion effect, model, osmotic effect, salinity, seed germination

张红香, 田雨, 周道玮, 郑伟, 王敏玲. 大麦种子对盐的发芽响应模型. 植物生态学报, 2012, 36(8): 849-858. DOI: 10.3724/SP.J.1258.2012.00849

ZHANG Hong-Xiang, TIAN Yu, ZHOU Dao-Wei, ZHENG Wei, WANG Min-Ling. Research on modeling germination response to salinity of barley seeds. Chinese Journal of Plant Ecology, 2012, 36(8): 849-858. DOI: 10.3724/SP.J.1258.2012.00849

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链接本文: https://www.plant-ecology.com/CN/10.3724/SP.J.1258.2012.00849

https://www.plant-ecology.com/CN/Y2012/V36/I8/849

图/表 7

图1 两个大麦品种‘Cask’和‘County’在4个温度下等渗的NaCl和聚乙二醇(PEG)溶液处理中的发芽时程。

Fig. 1 Germination courses for two varieties of barley ‘Cask’ and ‘County’ cultured in isotonic NaCl and polyethylene glycol (PEG) solutions at four temperatures.

表1 两个大麦品种在不同NaCl、聚乙二醇(PEG)及4个温度条件下种子发芽的水势模型参数评估

Table 1 Parameter estimate of hydrotime model for seed germination of two varieties of barley under different salinities, polyethylene glycol (PEG) solutions and four temperatures

品种 Variety	温度 Temperature (℃)	渗透调节物质 Osmotica	水势常数 θ_H (MPa·h)	最低水势 Ψ_b (50) (MPa)	误差 σ_Ψ_b (MPa)	R²
‘Cask’	5	NaCl	428	-2.51	0.63	0.83
		PEG	208	-1.22	0.61	0.66
	12	NaCl	115	-1.70	0.71	0.85
		PEG	65	-0.77	0.22	0.89
	20	NaCl	73	-1.72	1.09	0.84
		PEG	52	-1.23	0.64	0.68
	27	NaCl	36	-0.56	1.21	0.73
		PEG	34	-0.65	0.87	0.67
‘County’	5	NaCl	355	-2.55	0.83	0.58
		PEG	184	-1.32	0.56	0.62
	12	NaCl	115	-1.93	1.18	0.65
		PEG	63	-0.86	0.55	0.57
	20	NaCl	36	-1.35	0.72	0.73
		PEG	29	-1.01	0.49	0.67
	27	NaCl	20	-0.80	0.65	0.70
		PEG	30	-1.16	0.74	0.51

图2 两个大麦品种‘Cask’和‘County’在4个温度下发芽速率与外界盐浓度之间的关系(平均值±标准误差)。

Fig. 2 Germination rate plotted against external salinity concentration for two varieties of barley ‘Cask’ and ‘County’ at four temperatures (mean ± SE).

表2 两个大麦品种在不同NaCl盐度及4个温度条件下种子发芽的盐度模型参数评估

Table 2 Parameter estimate of salinity model for seed germination of two varieties of barley under different salinities and four temperatures

品种 Cultivar	温度 Temperature (℃)	萌发率 Germination (%)	盐度常数 θ_S (mmol·L^-1·d^-1)	最高盐度 S_m (mmol·L^-1)	R²	p
‘Cask’	5	1	3 333.3	621.3	0.99	0.000 8
		50	5 000.0	712.0	0.98	0.000 8
	12	1	833.3	552.8	0.98	0.001 0
		50	909.1	392.6	0.98	0.093 4
	20	1	500.0	612.4	0.99	0.000 6
		50	1 000.0	573.0	0.99	0.039 5
	27	1	416.7	609.6	0.99	0.000 7
		50^*
‘County’	5	1	3 333.3	796.0	0.99	0.000 3
		50	3 333.3	638.0	0.94	0.006 7
	12	1	769.2	600.3	0.96	0.003 1
		50	1 000.0	558.5	0.89	0.015 6
	20	1	357.1	528.9	0.96	0.003 5
		50	370.4	382.9	0.99	0.067 2
	27	1	227.3	390.9	0.88	0.223 7
		50^*

图3 水势模型和盐度模型估计的两个大麦品种50%种子发芽时间与实际发芽时间的比较。

Fig. 3 Comparison of germination time between the real data (50% germination) and the data predicted by hydrotime model and salinity model for two varieties of barley.

图4 两个大麦品种‘Cask’和‘County’在4个温度下等渗的NaCl和聚乙二醇(PEG)处理中发芽速率差异与外界水势之间的关系。

Fig. 4 Difference of germination rate between binate iso-osmotic NaCl and polyethylene glycol (PEG) plotted against external water potential for two varieties of barley ‘Cask’ and ‘County’ at four temperatures.

图5 盐对种子发芽影响的3种情况(以品种‘Cask’在5 ℃下的发芽速率为例)。

Fig. 5 Three situations of salt effect on seed germination (germination rate of varieties ‘Cask’ at 5 °C, for example).

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