亚适低温对生殖期草莓叶片结构和光合荧光特性的影响

doi:10.13304/j.nykjdb.2024.0301

摘要/Abstract

摘要：

为探究草莓在亚适低温下的适应机制，以宁玉和京藏香2个草莓品种为材料，以常温处理为对照，研究亚适低温胁迫对生殖期草莓株型及叶片表型、光合参数、快速叶绿素荧光参数、叶片超微结构的影响。结果表明，在亚适低温胁迫下，宁玉株型无明显变化，京藏香的株型由中间型逐渐开张，叶片渐变为黄绿色。随着亚适低温时间的延长，宁玉的叶面积、叶厚度和叶体积均显著减小，叶组织密度显著增加，比叶面积先增加后降低，叶干物质含量先降低后增大；京藏香叶面积和叶体积增加，叶厚度减小，叶组织密度和叶干物质量先减小后增大，比叶面积和叶组织密度先增大后减小。随着亚适低温时间的延长，宁玉叶片的叶绿素含量无显著变化；但京藏香叶片中叶绿素a含量显著增加。宁玉叶片的净光合速率、气孔导度和胞间CO₂浓度均在胁迫7 d时显著升高，胁迫14 d时有所降低，亚适低温致使其水分利用效率降低，虽在14 d时有所增加，但仍低于同期对照；京藏香叶片的净光合速率在胁迫14 d时显著降低，胞间CO₂浓度、气孔导度在胁迫7 d时显著升高，胁迫14 d回降，蒸腾速率在胁迫14 d时降低，水分利用效率降低。宁玉叶片在胁迫14 d时能量传递受阻（ΔW_OK>0）；而京藏香在胁迫7 d时已受到阻碍。亚适低温胁迫对宁玉和京藏香放氧复合体的影响较大，放氧复合物均失活（ΔW_OJ>0）。宁玉与京藏香对照组叶片的叶肉细胞完好，叶绿体等结构完整清晰。在亚适低温胁迫下，宁玉叶肉细胞的线粒体轻度肿胀，少数粗面内质网轻度扩张，胁迫14 d时，叶绿体中片层及垛叠结构模糊；京藏香在胁迫7 d时已出现轻微质壁分离现象，叶绿体结构溶解，外膜界限不清，片层结构排列紊乱，胁迫14 d后，叶绿体溶解变性，片层结构模糊。综上可见，草莓处于亚适低温胁迫下叶片会相应调整，但长时间亚适低温会降低叶片光合性能、伤害叶超微结构。亚适低温胁迫对京藏香光系统Ⅱ反应中心及叶绿体造成的伤害较宁玉更大，宁玉的植株状态、光合性能等指标相对稳定，其耐低温能力强于京藏香。

关键词: 草莓, 叶结构型性状, 光合, 亚适低温, 叶超微结构

Abstract:

In order to explore the adaptation mechanism of strawberries under suboptimal low temperature， 2 strawberry varieties of Ningyu and Jingzangxiang were taken as materials. The phenotype traits， photosynthetic parameters， rapid chlorophyll fluorescence parameters and leaf ultrastructure of strawberry leaves under different treatments during the reproductive period were determined. The results showed that， under suboptimal low temperature， there was no significant change on plant-type of Ningyu， while the plant-type of Jingzangxiang gradually opened from the intermediate type and the leaf color gradually changed to yellow green. With the prolongation of suboptimal low temperature， the leaf area， leaf thickness and leaf volume of Ningyu significantly decreased， the leaf tissue density significantly increased， the specific leaf area first increased and then decreased， and the leaf dry matter content firstly decreased and then increased. With the prolongation of suboptimal low temperature， the leaf area and volume of Jingzangxiang increased， while the leaf thickness decreased， the leaf tissue density and leaf dry matter content first decreased and then increased， the specific leaf area and density showed a trend of first increasing and then decreasing. With the prolongation of suboptimal low temperature， there was no significant change in chlorophyll content in leaves of Ningyu， however， the chlorophyll a content of Jingzangxiang increased significantly. The net photosynthetic rate， stomatal conductance and intercellular CO₂ concentration of Ningyu leaves all significantly increased after 7 d of stress， and decreased after 14 d of stress. Suboptimal low temperature led to a decrease in water use efficiency， although it increased after 14 d of stress， it was still lower than the control at the same period. For Jingzangxiang， the net photosynthetic rate of leaves significantly decreased after 14 d of stress， while the intercellular CO₂ concentration and stomatal conductance significantly increased after 7 d of stress and decreased after 14 d of stress， the transpiration rate under suboptimal low temperature treatment decreased after 14 d of stress， and the overall trend of water use efficiency was similar to that of Ningyu. Energy transfer of Ningyu leaves was hindered after 14 d of suboptimal low temperature treatment （ΔW_OK>0）， however， the Jingzangxiang had already been hindered after 7 d of stress. The suboptimal low temperature had a significant impact on the oxygen release complexes of Ningyu and Jingzangxiang， and both oxygen release complexes were inactivated （ΔW_OJ>0）. The leaf mesophyll cells of Ningyu and Jingzangxiang under control treatment were intact， and the chloroplast and other structures were intact and clear. Under suboptimal low temperature treatment， the mitochondria in the mesophyll cells of Ningyu were slightly swollen， and a few rough endoplasmic reticulum were slightly dilated. After 14 d of stress， the lamellae and stacking structure of chloroplasts became blurred. After 7 d of stress， Jingzangxiang showed slight cytoplasmic wall separation， chloroplast structure dissolution， unclear outer membrane boundary， and disordered arrangement of lamellar structure. After 14 d of stress， chloroplasts dissolved and denatured， and lamellar structure became blurred. In summary， the leaves of strawberry should adjust under suboptimal low temperature treatment， but long-term suboptimal low temperature could reduce the photosynthetic performance of the leaves and damage the leaf ultrastructure. The damage caused by suboptimal low temperature to the photosystemⅡ reaction center and chloroplasts of Jingzangxiang was greater than that of Ningyu. The plant status， photosynthetic performance and other indicators of Ningyu were relatively stable， and its ability to low temperature was stronger than Jingzangxiang.

Key words: strawberry, leaf structural traits, photosynthesis, suboptimal low temperature, leaf ultrastructure

中图分类号:

S668.4

杨馥霞, 贺欢, 汤玲, 李宽莹, 刘芬, 陈建军. 亚适低温对生殖期草莓叶片结构和光合荧光特性的影响[J]. 中国农业科技导报, 2025, 27(10): 51-62.

Fuxia YANG, Huan HE, Ling TANG, Kuanying LI, Fen LIU, Jianjun CHEN. Effects of Suboptimal Low Temperatures on Leaf Structure and Photosynthetic Fluorescence Characteristics of Strawberry During Reproductive Period[J]. Journal of Agricultural Science and Technology, 2025, 27(10): 51-62.

图/表 9

参考文献 28

[1]	高峰,俞立,卢尚琼,等.国外设施农业的现状及发展趋势[J].浙江林学院学报,2009,26(2):279-285.
	GAO F, YU L, LU S Q, et al.. Status quo and development trend of facility agriculture in foreign countries [J]. J. Zhejiang For. Coll., 2009, 26(2):279-285.
[2]	吴长征,蒲文宣,盛崧,等.亚适低温影响植物生长及氮营养的分子生理机制研究进展[J].中国农业科技导报, 2023,25 (1):16-25.
	WU C Z, PU W X, SHENG S, et al.. Research advance on molecular physiological mechanisms of the effect of suboptimal low temperatures on plant growth and nitrogen nutrition [J]. J. Agric. Sci. Technol., 2023, 25(1):16-25.
[3]	朱丽云,杨再强,李军,等.花期低温寡照对番茄开花坐果特性及果实品质的影响[J].中国农业气象,2017,38(7): 456-465.
	ZHU L Y, YANG Z Q, LI J, et al.. Effect of low temperature and weak light at flowering stage on flower-fruit characteristics of tomato [J]. Chin. J. Agrometeorol., 2017, 38(7):456-465.
[4]	江莎,胡阳,郑书馨,等.不同光强与光质对“达赛莱克特”草莓叶片形态结构的影响[J].电子显微学报,2009,28(5):453-461.
	JIANG S, HU Y, ZHENG S X, et al.. Morphologic effects of different light intensities and light qualities on the leaf of ‘Darselect’ strawberry (Fragaria ananassa Duch) [J]. J. Chin. Electron.Microsc. Soc., 2009, 28(5): 453-461.
[5]	王勋陵,王静.植物形态结构与环境[M].兰州:兰州大学出版社,1989:105-138.
[6]	李芳兰,包维楷.植物叶片形态解剖结构对环境变化的响应与适应[J].植物学通报,2005():118-127.
	LI F L, BAO W K. Responses of the morphological and anatomical structure of the plant leaf to environmental change [J]. Chin. Bull. Bot., 2005(S1): 118-127.
[7]	张元梅,樊卫国.草莓光合作用的研究进展[J].贵州农业科学,2016,44(9):24-29.
	ZHANG Y M, FAN W G. Advances in photosynthesis of strawberry [J]. Guizhou Agric. Sci., 2016, 44(9): 24-29.
[8]	LORENZO M, PINEDO M L, EQUIZA M A, et al.. Changes in apoplastic peroxidase activity and cell wall composition are associated with cold-induced morpho-anatomical plasticity of wheat leaves [J]. Plant Biol., 2019, 21(S1):84-94.
[9]	DUMLAO M R, DAREHSHOURI A, COHU C M, et al.. Low temperature acclimation of photosynthetic capacity and leaf morphology in the context of phloem loading type [J]. Photosynth. Res., 2012, 113(1):181-189.
[10]	郭玲玲.野生草莓属植物对温度的耐受能力与倍性及气候因子的相关性[D].太原:山西师范大学,2017.
	GUO L L. Tolerance of wild Fragaria species to temperature and their correlation with ploidy level and climate [D]. Taiyuan: Shanxi Normal University, 2017.
[11]	杨馥霞,汤玲,贺欢,等.取样部位对6个草莓品种低温半致死温度的影响[J].甘肃农业科技,2019(12):31-34.
[12]	张广华.弱光、低温胁迫对草莓(Fragariaananassa Duch.)光合作用的影响[D].保定:河北农业大学,2004.
	ZHANG G H. Eeffes of weak light and low temperature stress on photosynthesis in strawberry [D]. Baoding: Hebei Agricultural University, 2004.
[13]	周艳威,陈金慧,鲁路,等.杂交鹅掌楸体胚再生植株淹水胁迫下叶片超微结构及光合特性变化[J].林业科学,2018,54(3):19-28.
	ZHOU Y W, CHEN J H, LU L,et al.. Changes on leaf chloroplast ultrastructure and photosynthetic characteristics of Liriodendron sino-americanum somatic embryo regeneration seedlings under waterlogging stress [J]. Sci. Silvae Sin., 2018, 54(3):19-28.
[14]	关思慧,柴亚倩,崔洪鑫,等.低温胁迫对2个石榴品种幼苗光合参数和生理特性的影响[J].果树学报,2023,40(5):946-958.
	GUAN S H, CHAI Y Q, CUI H X, et al.. Effects of low temperature stress on photosynthetic parameters and phys-iological characteristics for seedlings of two pomegranate varieties [J]. J. Fruit Sci., 2023, 40(5):946-958.
[15]	刘慧英,朱祝军,史庆华.低温胁迫下嫁接对西瓜光合特性及叶绿素荧光参数影响的研究[J].石河子大学学报(自然科学版),2007,25(2):163-167.
	LIU H Y, ZHU Z J, SHI Q H. Effects of low temperature stress on characteristics of photosynthesis in leaves of own-rooted and grafted watermelon seedling [J]. J. Shihezi Univ. (Nat. Sci.), 2007, 25(2): 163-167.
[16]	田海涛,高培军,温国胜.7种箬竹抗寒特性比较[J].浙江林学院学报,2006,23(6):641-646.
	TIAN H T, GAO P J, WEN G S. Comparative study of cold resistance characteristics in seven Indocalamus spp [J]. J. Zhejiang For. Coll., 2006, 23(6):641-646.
[17]	邵怡若,许建新,薛立,等.低温胁迫时间对4种幼苗生理生化及光合特性的影响[J].生态学报,2013,33(14):4237-4247.
	SHAO Y R, XU J X, XUE L, et al.. Effects of low temperature stress on physiological-biochemical indexes and photosynthetic characteristics of seedlings of four plant species [J]. Acta Ecol. Sin., 2013, 33(14): 4237-4247.
[18]	徐超,王明田,杨再强,等.高温对温室草莓光合生理特性的影响及胁迫等级构建[J].应用生态学报,2021,32(1):231-240.
	XU C, WANG M T, YANG Z Q, et al.. Effects of high temperature on photosynthetic physiological characteristics of strawberry seedlings in greenhouse and construction of stress level [J]. Chin. J. Appl. Ecol., 2021, 32(1):231-240.
[19]	方平,杨鹤,牛晨,等.不同LED光质对人参种苗叶片生理特性和超微结构的影响[J].光谱学与光谱分析,2022,42(12):3864-3871.
	FANG P, YANG H, NIU C, et al.. Effects of different LED light quality on the physiological characteristics and ultrastructure of ginseng seedling leaves [J]. Spectrosc. Spectr. Anal., 2022, 42(12): 3864-3871.
[20]	蔺经,杨青松,王中华,等.梨杂种苗童区和成年区叶片光合荧光特征及超微结构研究[J].果树学报,2011,28(5):750-754.
	LIN J, YANG Q S, WANG Z H, et al.. Photosynthetic fluorescence characteristics and ultrastructure of juvenile zone and adult zone in pear hybrid seedlings [J]. J. Fruit Sci., 2011, 28(5):750-754.
[21]	何洁,刘鸿先,王以柔,等. 低温与植物的光合作用[J].植物生理学通讯,1986(2): 1-6.
	HE J, LIU H X, WANG Y R, et al.. Low temperature and photosythesis of plants [J]. Plant Physiol. J., 1986(2):1-6.
[22]	杜丽君,牛先前,林晓红,等.低温对枇杷苗叶片与根尖的生理状况及超微结构的影响[J].热带亚热带植物学报,2019,27(4):452-460.
	DU L J, NIU X Q, LIN X H, et al.. Influence of low temperature on physiological and cell ultrastructure of leaves and roots of Eriobotrya japonica seedlings [J]. J. Trop. Subtrop. Bot., 2019, 27(4):452-460.
[23]	周蕴薇.翠南报春叶片细胞超微结构对低温的适应性变化[J].园艺学报,2006,33(6):1365-1368.
	ZHOU Y W. Adapted responses of mesophyll cell ultrastructure in Primula sieboldii leaves cultured at different low temperatures [J]. Acta Hortic. Sin., 2006, 33(6):1365-1368.
[24]	刘芬,陈桂华,王悦,等.水稻淡黄叶突变体xws的光合特性与基因定位[J].核农学报,2022,36(6):1080-1088.
	LIU F, CHEN G H, WANG Y, et al.. Photosynthetic characteristics and gene mapping of pale yellow leaf rice mutant xws [J]. J. Nucl. Agric. Sci., 2022, 36(6):1080-1088.
[25]	郑丽梅,司龙亭,韩贵超.低温处理对不同耐寒性黄瓜幼苗叶片超微结构的影响[J].西北农业学报,2009,18(4):276-279.
	ZHENG L M, SI L T, HAN G C. Effects of low temperature treatment on the ultrastructure of seedling leaf of different cold resistance cucumber [J]. Acta Agric. Bor-Occid. Sin., 2009, 18(4): 276-279.
[26]	黄俊,郭世荣,吴震,等.弱光对不结球白菜光合特性与叶绿体超微结构的影响[J].应用生态学报,2007,18(2):352-358.
	HUANG J, GUO S R, WU Z, et al.. Effects of weak light on photosynthetic characteristics and chloroplast ultrastructure of non-heading Chinese cabbage [J]. Chin. J. Appl. Ecol., 2007, 18(2): 352-358.
[27]	冯梅.胡杨叶形变化与个体发育阶段的关系研究[D].阿拉尔:塔里木大学,2014.
	FENG M. Relationship populus euphratical leaf change and individual developmentol stages [D]. Alar: Tarim University, 2014.
[28]	李超.中亚热带九种常绿阔叶树种幼苗叶结构型性状相关性与叶经济谱分析[D].北京:中国林业科学研究院,2016.
	LI C. Analysis of relationships among leaf structural traits and economics spectrum of the nine evergreen broad leaved treeseedlings in the Mid-subtropical Zone of China [D]. Beijing: Chinese Academy of Forestry, 2016.

品种 Variety	处理Treatment	胁迫时间 Stress time/d	叶面积 LS/cm²	叶厚度 LT/mm	叶体积 LV/cm³	叶组织密度 LTD/（g·cm^-3）	比叶面积 SLA/（cm²·g^-1）	叶干物质含量 LDMC/（g·g^-1）
宁玉Ningyu	CK	0	32.23±3.25 a	0.44±0.03 a	1.43±0.20 a	0.15±0.03 c	157.36±29.04 abc	0.28±0.04 b
		7	27.85±4.45 b	0.35±0.04 b	0.99±0.22 b	0.17±0.02 b	170.32±32.01 a	0.24±0.03 c
		14	28.44±3.43 b	0.29±0.02 c	0.81±0.14 c	0.24±0.02 a	148.49±10.80 bc	0.29±0.01 ab
	LT	0	32.23±3.25 a	0.44±0.03 a	1.43±0.20 a	0.15±0.03 c	157.36±29.04 abc	0.28±0.04 b
		7	27.38±2.78 b	0.37±0.04 b	1.01±0.20 b	0.16±0.02 bc	168.85±16.61 ab	0.25±0.02 c
		14	26.09±1.43 b	0.29±0.03 c	0.75±0.10 c	0.25±0.02 a	141.49±8.48 c	0.30±0.03 a
京藏香 Jingzangxiang	CK	0	18.45±6.28 b	0.34±0.03 a	0.63±0.23 b	0.40±0.67 a	143.34±49.85 b	0.35±0.21 a
		7	20.75±2.47 b	0.30±0.04 b	0.64±0.14 b	0.21±0.05 a	160.86±32.59 ab	0.26±0.05 ab
		14	25.04±3.85 a	0.27±0.03 c	0.68±0.16 ab	0.25±0.04 a	149.67±13.02 b	0.31±0.01 ab
	LT	0	18.45±6.28 b	0.34±0.03 a	0.63±0.23 b	0.40±0.67 a	143.34±49.85 b	0.35±0.21 a
		7	21.81±2.44 ab	0.32±0.03 ab	0.70±0.13 ab	0.18±0.03 a	180.97±25.16 a	0.23±0.02 b
		14	25.28±4.18 a	0.32±0.04 ab	0.81±0.18 a	0.24±0.04 a	137.31±17.36 b	0.32±0.03 ab

品种 Variety	处理Treatment	胁迫时间 Stress time/d	叶面积 LS/cm²	叶厚度 LT/mm	叶体积 LV/cm³	叶组织密度 LTD/（g·cm^-3）	比叶面积 SLA/（cm²·g^-1）	叶干物质含量 LDMC/（g·g^-1）
宁玉Ningyu	CK	0	32.23±3.25 a	0.44±0.03 a	1.43±0.20 a	0.15±0.03 c	157.36±29.04 abc	0.28±0.04 b
		7	27.85±4.45 b	0.35±0.04 b	0.99±0.22 b	0.17±0.02 b	170.32±32.01 a	0.24±0.03 c
		14	28.44±3.43 b	0.29±0.02 c	0.81±0.14 c	0.24±0.02 a	148.49±10.80 bc	0.29±0.01 ab
	LT	0	32.23±3.25 a	0.44±0.03 a	1.43±0.20 a	0.15±0.03 c	157.36±29.04 abc	0.28±0.04 b
		7	27.38±2.78 b	0.37±0.04 b	1.01±0.20 b	0.16±0.02 bc	168.85±16.61 ab	0.25±0.02 c
		14	26.09±1.43 b	0.29±0.03 c	0.75±0.10 c	0.25±0.02 a	141.49±8.48 c	0.30±0.03 a
京藏香 Jingzangxiang	CK	0	18.45±6.28 b	0.34±0.03 a	0.63±0.23 b	0.40±0.67 a	143.34±49.85 b	0.35±0.21 a
		7	20.75±2.47 b	0.30±0.04 b	0.64±0.14 b	0.21±0.05 a	160.86±32.59 ab	0.26±0.05 ab
		14	25.04±3.85 a	0.27±0.03 c	0.68±0.16 ab	0.25±0.04 a	149.67±13.02 b	0.31±0.01 ab
	LT	0	18.45±6.28 b	0.34±0.03 a	0.63±0.23 b	0.40±0.67 a	143.34±49.85 b	0.35±0.21 a
		7	21.81±2.44 ab	0.32±0.03 ab	0.70±0.13 ab	0.18±0.03 a	180.97±25.16 a	0.23±0.02 b
		14	25.28±4.18 a	0.32±0.04 ab	0.81±0.18 a	0.24±0.04 a	137.31±17.36 b	0.32±0.03 ab

品种 Variety	处理 Treatment	胁迫时间 Stress time/d	叶绿素a Chl a/（mg·g^-1）	叶绿素b Chl b/（mg·g^-1）
宁玉Ningyu	CK	0	2.33±0.04 a	1.32±0.02 a
		7	2.29±0.11 a	1.29±0.14 a
		14	2.28±0.08 a	1.24±0.07 a
	LT	0	2.33±0.04 a	1.32±0.02 a
		7	2.24±0.03 a	1.23±0.06 a
		14	2.28±0.06 a	1.23±0.05 a
京藏香 Jingzangxiang	CK	0	2.11±0.01 b	1.13±0.04 ab
		7	2.14±0.02 ab	1.09±0.02 b
		14	2.15±0.04 ab	1.16±0.02 a
	LT	0	2.11±0.01 b	1.13±0.04 ab
		7	2.14±0.04 ab	1.10±0.01 b
		14	2.18±0.03 a	1.15±0.00 a

品种 Variety	处理 Treatment	胁迫时间 Stress time/d	叶绿素a Chl a/（mg·g^-1）	叶绿素b Chl b/（mg·g^-1）
宁玉Ningyu	CK	0	2.33±0.04 a	1.32±0.02 a
		7	2.29±0.11 a	1.29±0.14 a
		14	2.28±0.08 a	1.24±0.07 a
	LT	0	2.33±0.04 a	1.32±0.02 a
		7	2.24±0.03 a	1.23±0.06 a
		14	2.28±0.06 a	1.23±0.05 a
京藏香 Jingzangxiang	CK	0	2.11±0.01 b	1.13±0.04 ab
		7	2.14±0.02 ab	1.09±0.02 b
		14	2.15±0.04 ab	1.16±0.02 a
	LT	0	2.11±0.01 b	1.13±0.04 ab
		7	2.14±0.04 ab	1.10±0.01 b
		14	2.18±0.03 a	1.15±0.00 a

品种 Variety	处理Treatment	胁迫时间 Stress time/d	净光合速率P_n/ （μmol·m^-2·s^-1）	胞间CO₂浓度C_i/ （μmol·mol^-1）	气孔导度G_s/ （mol·m^-2·s^-1）	蒸腾速率T_r/ （mmol·m^-2·s^-1）	水分利用效率WUE/（mmol·mol^-1）
宁玉Ningyu	CK	0	10.13±1.17 b	333.03±23.76 b	0.15±0.03 b	3.53±1.32 a	3.18±1.32 c
		7	10.52±0.39 b	367.27±3.66 b	0.17±0.01 b	3.03±0.20 ab	3.47±0.11 bc
		14	9.40±0.22 b	334.56±17.02 b	0.12±0.01 b	1.62±0.08 b	5.83±0.42 a
	LT	0	10.13±1.17 b	333.03±23.76 b	0.15±0.03 b	3.53±1.32 a	3.18±1.32 c
		7	12.00±0.49 a	452.21±26.03 a	0.29±0.03 a	4.41±0.51 a	2.74±0.22 c
		14	9.30±0.05 b	357.05±25.40 b	0.15±0.03 b	1.93±0.34 b	4.93±0.92 ab
京藏香 Jingzangxiang	CK	0	9.71±0.61 ab	317.06±27.14 cd	0.12±0.03 b	2.99±0.64 a	3.32±0.53 b
		7	9.26±0.35 ab	361.21±19.05 b	0.14±0.03 b	1.92±0.26 b	4.88±0.52 a
		14	9.85±0.12 a	306.95±7.69 d	0.12±0.00 b	1.98±0.10 b	4.98±0.24 a
	LT	0	9.71±0.61 ab	317.06±27.14 cd	0.12±0.03 b	2.99±0.64 a	3.32±0.53 b
		7	9.59±0.38 ab	401.51±6.07 a	0.22±0.05 a	3.46±0.52 a	2.80±0.29 b
		14	8.79±0.87 b	348.13±28.11 bc	0.09±0.03 b	1.82±0.42 b	4.94±0.89 a