Leaf anatomical structures and ecological adaptabilities to light of three alfalfa cultivars with different fall dormancies under shading during overwintering

doi:10.3724/SP.J.1258.2012.00333

Abstract

Abstract:

Aims This research studied effects of light intensity on leaf anatomical characteristics of three alfalfa (Medicago sativa) cultivars (‘Victoria’, ‘Ameristand 201’and ‘Eureka’) with different fall dormancy during overwintering in climatic transitional regions from north to south China. Our objective was to determine leaf anatomical characteristics sensitive to light intensity and correlate fall dormancy and shade tolerance of overwintering alfalfa.
Methods We cultured seedlings of the alfalfa cultivars for 70 days under four light intensity levels: 100%, 43%, 21% and 7% of full natural light intensity. Using the paraffin section method, fluorescence microscopy technique and Image-Pro Plus 6.0, we measured leaf epidermises, mesophyll tissues, and some leaf-integrated characteristics under different shade conditions to examine effects of light intensity on leaf anatomical structures.
Important findings Cuticle thicknesses of lower and upper epidermis and stomatal densities and apertures of the cultivars significantly decreased while thicknesses of upper and lower epidermis increased under with shading. Widths of spongy cell increased and thicknesses of palisade parenchyma, layers of palisade parenchyma and palisade-spongy ratio significantly decreased with decreased light intensity, but thicknesses of spongy parenchyma and widths of palisade cells had different trends among the cultivars. Leaf, mesophyll and midrib thicknesses and cell tense ratio of the cultivars significantly decreased, and vein protuberant degree did not significantly change when the spongy ratio increased significantly with increasing shade. Significant differences in range and plasticity indexes of leaf anatomical characteristics among the cultivars under different shading conditions showed different shade-tolerant mechanisms among them. Pearson correlation analysis showed that stomatal density, thickness of palisade parenchyma, mesophyll thickness, leaf thickness and palisade-spongy ratio were positively correlated with light intensity, which meant that these leaf characteristics may be anatomically sensitive in response to light intensity. ‘Victoria’ had fewer leaf anatomical characteristics correlated with light intensity and also had weaker association to some of these five characteristics than the other cultivars. Results suggested that fall dormancy of alfalfa could be relevant to its shade tolerance during overwintering, and semi-dormancy cultivar of alfalfa has a higher shade tolerance than other cultivars. The order of shade tolerance of three alfalfa cultivars is semi-dormancy cultivar ‘Victoria’ > dormancy cultivar ‘Ameristand 201’ ≥ non-dormancy cultivar ‘Eureka’.

Key words: ecological adaptation, fall dormancy, leaf anatomical structures, Medicago sativa, plasticity, shading, overwinter

QIN Feng-Fei,LI Qiang,CUI Zhao-Ming,LI Hong-Ping,YANG Zhi-Ran. Leaf anatomical structures and ecological adaptabilities to light of three alfalfa cultivars with different fall dormancies under shading during overwintering[J]. Chin J Plant Ecol, 2012, 36(4): 333-345.

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Figures/Tables 5

References 45

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项目 Item	遮阴处理 Shading treatment		品种 Cultivar
项目 Item	遮阴处理 Shading treatment	‘巨人201’ ‘Ameristand 201’	‘维多利亚’ ‘Victoria’	‘游客’ ‘Eureka’
上表皮角质层厚度 Cuticle thickness of upper epidermis (μm)	L₀	3.73 ± 0.26^a	3.97 ± 0.13^a	3.82 ± 0.12^a
	L₁	3.55 ± 0.21^a	3.58 ± 0.09^b	3.63 ± 0.14^a
	L₂	3.42 ± 0.11^ab	3.56 ± 0.13^b	3.23 ± 0.10^b
	L₃	2.89 ± 0.18^b	3.48 ± 0.13^b	3.14 ± 0.07^b
	p 可塑性指数 PI	0.046* 0.225	0.027* 0.123	0.000** 0.178
下表皮角质层厚度 Cuticle thickness of lower epidermis (μm)	L₀	4.41 ± 0.27^a	3.48 ± 0.20^a	3.32 ± 0.18^a
	L₁	3.23 ± 0.15^b	3.30 ± 0.09^ab	3.24 ± 0.12^a
	L₂	3.05 ± 0.09^b	3.25 ± 0.12^ab	3.07 ± 0.08^ab
	L₃	2.97 ± 0.15^b	2.89 ± 0.09^b	2.86 ± 0.12^b
	p 可塑性指数 PI	0.000** 0.327	0.041* 0.170	0.054 0.139
上表皮厚度 Thickness of upper epidermis (μm)	L₀	21.75 ± 1.21^a	17.46 ± 0.54^a	18.19 ± 0.72^a
	L₁	22.11 ± 1.31^a	18.92 ± 0.75^ab	18.26 ± 0.62^a
	L₂	24.04 ± 0.90^a	20.60 ± 1.11^bc	18.44 ± 0.80^a
	L₃	24.31 ± 1.18^a	21.78 ± 0.95^c	18.54 ± 0.66^a
	p 可塑性指数 PI	0.357 0.105	0.003** 0.198	0.984 0.019
下表皮厚度 Thickness of lower epidermis (μm)	L₀	15.64 ± 0.46^a	16.00 ± 0.54^a	15.47 ± 0.69^a
	L₁	16.16 ± 0.73^a	17.04 ± 0.90^ab	15.43 ± 0.58^a
	L₂	19.74 ± 0.98^b	17.28 ± 0.89^ab	14.36 ± 0.48^a
	L₃	20.96 ± 0.99^b	18.76 ± 0.73^b	13.85 ± 0.40^a
	p 可塑性指数 PI	0.000** 0.254	0.096 0.147	0.096 0.104
气孔密度(个/叶片横切面) Stomatal density (number of leaf transverse section )	L₀	9.67 ± 1.26^a	13.83 ± 1.05^a	11.00 ± 1.52^a
	L₁	6.83 ± 0.79^ab	5.67 ± 0.21^b	7.67 ± 0.33^b
	L₂	5.25 ± 0.48^b	5.17 ± 0.54^b	5.83 ± 0.48^b
	L₃	5.00 ± 0.82^b	4.50 ± 0.56^b	5.17 ± 0.95^b
	p 可塑性指数 PI	0.013* 0.483	0.000** 0.675	0.001** 0.530
气孔开度 Stomata aperture (μm)	L₀	3.78 ± 0.41^a	2.73 ± 0.20^a	2.65 ± 0.21^a
	L₁	2.94 ± 0.27^ab	2.94 ± 0.25^a	2.82 ± 0.32^a
	L₂	2.39 ± 0.30^bc	1.86 ± 0.24^b	1.48 ± 0.25^b
	L₃	1.90 ± 0.29^c	1.73 ± 0.17^b	1.39 ± 0.21^b
	p 可塑性指数 PI	0.003** 0.497	0.000** 0.412	0.000** 0.507

项目 Item	遮阴处理 Shading treatment		品种 Cultivar
项目 Item	遮阴处理 Shading treatment	‘巨人201’ ‘Ameristand 201’	‘维多利亚’ ‘Victoria’	‘游客’ ‘Eureka’
上表皮角质层厚度 Cuticle thickness of upper epidermis (μm)	L₀	3.73 ± 0.26^a	3.97 ± 0.13^a	3.82 ± 0.12^a
	L₁	3.55 ± 0.21^a	3.58 ± 0.09^b	3.63 ± 0.14^a
	L₂	3.42 ± 0.11^ab	3.56 ± 0.13^b	3.23 ± 0.10^b
	L₃	2.89 ± 0.18^b	3.48 ± 0.13^b	3.14 ± 0.07^b
	p 可塑性指数 PI	0.046* 0.225	0.027* 0.123	0.000** 0.178
下表皮角质层厚度 Cuticle thickness of lower epidermis (μm)	L₀	4.41 ± 0.27^a	3.48 ± 0.20^a	3.32 ± 0.18^a
	L₁	3.23 ± 0.15^b	3.30 ± 0.09^ab	3.24 ± 0.12^a
	L₂	3.05 ± 0.09^b	3.25 ± 0.12^ab	3.07 ± 0.08^ab
	L₃	2.97 ± 0.15^b	2.89 ± 0.09^b	2.86 ± 0.12^b
	p 可塑性指数 PI	0.000** 0.327	0.041* 0.170	0.054 0.139
上表皮厚度 Thickness of upper epidermis (μm)	L₀	21.75 ± 1.21^a	17.46 ± 0.54^a	18.19 ± 0.72^a
	L₁	22.11 ± 1.31^a	18.92 ± 0.75^ab	18.26 ± 0.62^a
	L₂	24.04 ± 0.90^a	20.60 ± 1.11^bc	18.44 ± 0.80^a
	L₃	24.31 ± 1.18^a	21.78 ± 0.95^c	18.54 ± 0.66^a
	p 可塑性指数 PI	0.357 0.105	0.003** 0.198	0.984 0.019
下表皮厚度 Thickness of lower epidermis (μm)	L₀	15.64 ± 0.46^a	16.00 ± 0.54^a	15.47 ± 0.69^a
	L₁	16.16 ± 0.73^a	17.04 ± 0.90^ab	15.43 ± 0.58^a
	L₂	19.74 ± 0.98^b	17.28 ± 0.89^ab	14.36 ± 0.48^a
	L₃	20.96 ± 0.99^b	18.76 ± 0.73^b	13.85 ± 0.40^a
	p 可塑性指数 PI	0.000** 0.254	0.096 0.147	0.096 0.104
气孔密度(个/叶片横切面) Stomatal density (number of leaf transverse section )	L₀	9.67 ± 1.26^a	13.83 ± 1.05^a	11.00 ± 1.52^a
	L₁	6.83 ± 0.79^ab	5.67 ± 0.21^b	7.67 ± 0.33^b
	L₂	5.25 ± 0.48^b	5.17 ± 0.54^b	5.83 ± 0.48^b
	L₃	5.00 ± 0.82^b	4.50 ± 0.56^b	5.17 ± 0.95^b
	p 可塑性指数 PI	0.013* 0.483	0.000** 0.675	0.001** 0.530
气孔开度 Stomata aperture (μm)	L₀	3.78 ± 0.41^a	2.73 ± 0.20^a	2.65 ± 0.21^a
	L₁	2.94 ± 0.27^ab	2.94 ± 0.25^a	2.82 ± 0.32^a
	L₂	2.39 ± 0.30^bc	1.86 ± 0.24^b	1.48 ± 0.25^b
	L₃	1.90 ± 0.29^c	1.73 ± 0.17^b	1.39 ± 0.21^b
	p 可塑性指数 PI	0.003** 0.497	0.000** 0.412	0.000** 0.507

项目 Item	遮阴处理 Shading treatment		品种 Cultivar
项目 Item	遮阴处理 Shading treatment	‘巨人201’ ‘Ameristand 201’	‘维多利亚’ ‘Victoria’	‘游客’ ‘Eureka’
栅栏组织厚度 Thickness of palisade parenchyma (μm)	L₀	96.11 ± 2.12^a	89.71 ± 3.27^a	101.08 ± 2.72^a
	L₁	71.83 ± 3.73^b	66.60 ± 1.22^b	74.44 ± 2.78^b
	L₂	54.41 ± 3.56^c	65.85 ± 2.07^b	51.70 ± 1.32^c
	L₃	47.12 ± 1.49^c	55.77 ± 3.00^c	48.78 ± 2.53^c
	p 可塑性指数 PI	0.000** 0.510	0.000** 0.378	0.000** 0.517
栅栏细胞宽度 Width of palisade cell (μm)	L₀	16.60 ± 0.54^a	14.67 ± 0.35^a	15.75 ± 0.47^a
	L₁	16.41 ± 0.38^a	14.74 ± 0.44^a	15.06 ± 0.48^a
	L₂	14.03 ± 0.31^b	14.85 ± 0.30^a	12.90 ± 0.28^b
	L₃	12.85 ± 0.45^b	16.35 ± 0.30^b	12.58 ± 0.34^b
	p 可塑性指数 PI	0.000** 0.226	0.003** 0.119	0.000** 0.201
栅栏组织细胞层数 Layer of palisade cell	L₀	2-3	2-3	2-3
	L₁	2-3	1-2	1-2
	L₂	1-2	1-2	1-2
	L₃	1-2	1	1
海绵组织厚度 Thickness of spongy parenchyma (μm)	L₀	70.90 ± 1.97^a	57.82 ± 2.12^a	67.91 ± 3.44^a
	L₁	67.86 ± 4.16^a	57.67 ± 1.17^a	63.68 ± 2.09^a
	L₂	66.76 ± 2.13^a	64.35 ± 2.08^a	55.79 ± 1.38^b
	L₃	61.48 ± 3.43^b	79.41 ± 3.25^b	54.18 ± 2.35^b
	p 可塑性指数 PI	0.248 0.133	0.000** 0.274	0.000** 0.202
海绵细胞宽度 Width of spongy cell (μm)	L₀	9.13 ± 0.42^a	11.67 ± 0.38^a	11.78 ± 0.46^a
	L₁	12.20 ± 0.40^b	11.91 ± 0.46^a	12.11 ± 0.36^a
	L₂	12.84 ± 0.33^b	12.57 ± 0.34^a	12.26 ± 0.21^a
	L₃	12.96 ± 0.26^b	15.07 ± 0.55^b	13.87 ± 0.61^b
	p 可塑性指数 PI	0.000** 0.296	0.000** 0.226	0.004** 0.151
栅栏组织厚度/海绵组织厚度 Palisade-spongy ratio	L₀	1.37 ± 0.03^a	1.58 ± 0.13^a	1.56 ± 0.08^a
	L₁	1.11 ± 0.06^b	1.15 ± 0.04^b	1.17 ± 0.03^b
	L₂	0.83 ± 0.06^c	1.06 ± 0.05^bc	0.93 ± 0.03^c
	L₃	0.89 ± 0.03^c	0.83 ± 0.10^c	0.90 ± 0.05^c
	p 可塑性指数 PI	0.000** 0.394	0.000** 0.475	0.000** 0.423

项目 Item	遮阴处理 Shading treatment		品种 Cultivar
项目 Item	遮阴处理 Shading treatment	‘巨人201’ ‘Ameristand 201’	‘维多利亚’ ‘Victoria’	‘游客’ ‘Eureka’
栅栏组织厚度 Thickness of palisade parenchyma (μm)	L₀	96.11 ± 2.12^a	89.71 ± 3.27^a	101.08 ± 2.72^a
	L₁	71.83 ± 3.73^b	66.60 ± 1.22^b	74.44 ± 2.78^b
	L₂	54.41 ± 3.56^c	65.85 ± 2.07^b	51.70 ± 1.32^c
	L₃	47.12 ± 1.49^c	55.77 ± 3.00^c	48.78 ± 2.53^c
	p 可塑性指数 PI	0.000** 0.510	0.000** 0.378	0.000** 0.517
栅栏细胞宽度 Width of palisade cell (μm)	L₀	16.60 ± 0.54^a	14.67 ± 0.35^a	15.75 ± 0.47^a
	L₁	16.41 ± 0.38^a	14.74 ± 0.44^a	15.06 ± 0.48^a
	L₂	14.03 ± 0.31^b	14.85 ± 0.30^a	12.90 ± 0.28^b
	L₃	12.85 ± 0.45^b	16.35 ± 0.30^b	12.58 ± 0.34^b
	p 可塑性指数 PI	0.000** 0.226	0.003** 0.119	0.000** 0.201
栅栏组织细胞层数 Layer of palisade cell	L₀	2-3	2-3	2-3
	L₁	2-3	1-2	1-2
	L₂	1-2	1-2	1-2
	L₃	1-2	1	1
海绵组织厚度 Thickness of spongy parenchyma (μm)	L₀	70.90 ± 1.97^a	57.82 ± 2.12^a	67.91 ± 3.44^a
	L₁	67.86 ± 4.16^a	57.67 ± 1.17^a	63.68 ± 2.09^a
	L₂	66.76 ± 2.13^a	64.35 ± 2.08^a	55.79 ± 1.38^b
	L₃	61.48 ± 3.43^b	79.41 ± 3.25^b	54.18 ± 2.35^b
	p 可塑性指数 PI	0.248 0.133	0.000** 0.274	0.000** 0.202
海绵细胞宽度 Width of spongy cell (μm)	L₀	9.13 ± 0.42^a	11.67 ± 0.38^a	11.78 ± 0.46^a
	L₁	12.20 ± 0.40^b	11.91 ± 0.46^a	12.11 ± 0.36^a
	L₂	12.84 ± 0.33^b	12.57 ± 0.34^a	12.26 ± 0.21^a
	L₃	12.96 ± 0.26^b	15.07 ± 0.55^b	13.87 ± 0.61^b
	p 可塑性指数 PI	0.000** 0.296	0.000** 0.226	0.004** 0.151
栅栏组织厚度/海绵组织厚度 Palisade-spongy ratio	L₀	1.37 ± 0.03^a	1.58 ± 0.13^a	1.56 ± 0.08^a
	L₁	1.11 ± 0.06^b	1.15 ± 0.04^b	1.17 ± 0.03^b
	L₂	0.83 ± 0.06^c	1.06 ± 0.05^bc	0.93 ± 0.03^c
	L₃	0.89 ± 0.03^c	0.83 ± 0.10^c	0.90 ± 0.05^c
	p 可塑性指数 PI	0.000** 0.394	0.000** 0.475	0.000** 0.423

项目 Item	遮阴处理 Shading treatment		品种 Cultivar
项目 Item	遮阴处理 Shading treatment	‘巨人201’ ‘Ameristand 201’	‘维多利亚’ ‘Victoria’	‘游客’ ‘Eureka’
叶片厚度 Leaf thickness (μm)	L₀	241.85 ± 5.06^a	218.51 ± 3.78^a	242.94 ± 3.79^a
	L₁	217.38 ± 6.61^b	184.69 ± 4.56^b	202.13 ± 3.40^b
	L₂	179.52 ± 5.05^c	173.01 ± 3.05^bc	147.42 ± 1.54^c
	L₃	178.99 ± 2.32^c	172.18 ± 5.09^c	153.76 ± 4.12^c
	p 可塑性指数 PI	0.000** 0.26	0.000** 0.212	0.000** 0.393
叶肉厚度 Mesophyll thickness (μm)	L₀	164.37 ± 3.56^a	156.90 ± 2.52^a	171.53 ± 4.01^a
	L₁	143.87 ± 5.68^b	120.68 ± 1.44^b	140.65 ± 2.06^b
	L₂	119.39 ± 3.77^c	118.99 ± 2.30^b	104.97 ± 1.94^c
	L₃	116.20 ± 4.02^c	110.58 ± 3.31^c	101.19 ± 3.81^c
	p 可塑性指数 PI	0.000** 0.293	0.000** 0.295	0.000** 0.410
中脉厚度 Midrib thickness (μm)	L₀	388.99 ± 32.24^a	402.17 ± 23.00^a	511.23 ± 20.63^a
	L₁	370.22 ± 8.82^a	380.37 ± 24.85^a	387.18 ± 19.31^b
	L₂	367.07 ± 2.13^a	374.11 ± 15.78^a	275.58 ± 11.58^c
	L₃	278.21 ± 11.50^b	292.78 ± 9.35^b	274.62 ± 2.63^c
	p 可塑性指数 PI	0.001** 0.285	0.000** 0.272	0.000** 0.463
组织结构紧密度 Cell tense ratio	L₀	0.40 ± 0.01^a	0.41 ± 0.02^a	0.42 ± 0.02^a
	L₁	0.33 ± 0.02^b	0.39 ± 0.01^ab	0.37 ± 0.02^ab
	L₂	0.32 ± 0.02^b	0.38 ± 0.02^ab	0.33 ± 0.02^b
	L₃	0.26 ± 0.01^c	0.34 ± 0.02^b	0.34 ± 0.02^b
	p 可塑性指数 PI	0.000** 0.350	0.070 0.171	0.037* 0.21
组织结构疏松度 Spongy ratio	L₀	0.30 ± 0.01^a	0.27 ± 0.01^a	0.28 ± 0.02^a
	L₁	0.31 ± 0.02^a	0.34 ± 0.02^a	0.31 ± 0.01^a
	L₂	0.40 ± 0.03^b	0.37 ± 0.01^ab	0.38 ± 0.01^b
	L₃	0.34 ± 0.03^ab	0.47 ± 0.07^b	0.39 ± 0.02^b
	p 可塑性指数 PI	0.035* 0.250	0.006** 0.426	0.000** 0.282
叶脉突起度 Vein protuberant degree	L₀	1.61 ± 0.22^a	1.79 ± 0.21^a	2.11 ± 0.15^a
	L₁	1.72 ± 0.08^a	2.15 ± 0.31^a	1.94 ± 0.21^a
	L₂	2.21 ± 0.15^b	2.17 ± 0.12^a	1.77 ± 0.11^a
	L₃	1.54 ± 0.11^a	1.81 ± 0.18^a	1.78 ± 0.07^a
	p 可塑性指数 PI	0.037* 0.303	0.368 0.175	0.364 0.161