不同光合类型牧草对干旱-复水的光合生理响应及生长适应策略

doi:10.17521/cjpe.2021.0203

摘要/Abstract

摘要：

基于干旱频率增加、强度增大这一全球降水变化背景, 探究干旱-复水条件下不同功能群(C₃和C₄)植物的光合生理响应及生长适应策略有助于预测降水格局变化条件下草地的植被组成和生态系统功能。该研究采用盆栽实验, 以松嫩草地生长的一年生C₃ (4种)和C₄ (3种)牧草为实验材料, 设置了对照、中度干旱和重度干旱3个水分处理水平, 在干旱末期及复水期对植物进行气体交换、生物量和比叶质量的测量。在干旱条件下, 各物种净光合速率和气孔导度均呈下降趋势, 水分利用效率呈上升趋势。干旱对不同植物光合指标的影响存在功能群差异, 随干旱程度的增加C₄植物逐渐丧失光合优势, 重度干旱对C₄植物净光合速率的影响较C₃植物更加明显。由于干旱条件下C₃植物光合固碳主要受气孔限制而C₄植物主要受代谢限制, 因此复水后C₄植物净光合速率恢复速度较C₃植物慢。干旱条件下, 各物种的生物量降低, 根冠比和比叶质量升高, 干旱对C₃植物各生长指标的影响均大于C₄植物; 复水处理后, C₃植物生物量随干旱强度增加呈下降趋势, 而C₄植物的生物量与对照相比无显著差异。

关键词: 干旱, 复水, 功能群, 光合限制, 根冠比

Abstract:

Aims Based on the background of increasing drought frequency and intensity globally, investigating the photosynthetic properties and growth adaptation of annual grasses differed in photosynthetic pathway (C₃ and C₄) in response to drought-rehydration conditions is useful to predict the changes of grassland ecosystem composition, structure and function in the context of global climate change. Methods The study was conducted as a pot experiment with four annual C₃ and three C₄ grasses widely grown in the Songnen Grassland. Three water levels were set up including control, moderate drought and severe drought. Plant photosynthetic (leaf gas exchange) and growth (biomass, leaf mass per area etc.) parameters were measured at the end of the drought and during the rehydration periods. Important findings The net photosynthetic rate (A) and stomatal conductance (G_s) of all studied species showed a decreasing trend and water use efficiency showed an increasing trend under the drought conditions. There were functional group differences in the effects of drought on photosynthetic properties of the studied plants. The effects of the severe drought on net photosynthetic rate of the C₄ plants are more pronounced than that of the C₃ plants, with the C₄ plants gradually losing their photosynthetic advantage as drought severity increases. The A of the C₄ plants recovered more slowly than that of the C₃ plants after the rehydration because of carbon assimilation in the C₃ plants was mainly restricted by stomata limitation while it in the C₄ plants was mainly restricted by metabolic limitation. The biomass of all studied species decreased, but the root to shoot ratio and leaf mass per area increased, under the drought conditions. The effects of drought on all growth indicators were greater in the C₃ plants than in the C₄ plants. After the rehydration, the biomass of C₃ plants showed a decreasing trend with increasing drought intensity, while the biomass of C₄ plants was not significantly different from the control treatment.

Key words: drought, rehydration, functional group, photosynthetic limitation, root to shoot ratio

李斐, 孙明伟, 钟尚志, 宋文政, 钟晓月, 孙伟. 不同光合类型牧草对干旱-复水的光合生理响应及生长适应策略. 植物生态学报, 2022, 46(1): 74-87. DOI: 10.17521/cjpe.2021.0203

Fei LI, Ming-Wei SUN, Shang-Zhi ZHONG, Wen-Zheng SONG, Xiao-Yue ZHONG, Wei SUN. Photosynthetic physiology and growth adaptation of herbages with different photosynthetic pathways in response to drought-rehydration. Chinese Journal of Plant Ecology, 2022, 46(1): 74-87. DOI: 10.17521/cjpe.2021.0203

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https://www.plant-ecology.com/CN/Y2022/V46/I1/74

图/表 9

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功能群 Functional group	时期 Period	处理 Treatment	净光合速率 Net photosynthetic rate (μmol·m^-2·s^-1)	气孔导度 Stomatal conductance (mol·m^-2·s^-1)	蒸腾速率 Transpiration rate (mmol·m^-2·s^-1)	水分利用效率 Water use efficiency (μmol·mmol^-1)
C₃	干旱 Drought	对照 CK	13.60 ± 1.13^a	0.51 ± 0.08^a	17.30 ± 1.48^a	0.82 ± 0.07^a
		中度干旱 MD	10.50 ± 1.05^a	0.43 ± 0.08^a	13.30 ± 1.11^b	0.84 ± 0.12^a
		重度干旱 SD	8.13 ± 1.06^b	0.14 ± 0.02^b	6.29 ± 1.03^c	1.48 ± 0.23^b
	复水 Rehydration	对照 CK	15.90 ± 0.44	0.59 ± 0.09	1.12 ± 0.09	0.85 ± 0.27
		中度干旱 MD	15.90 ± 0.51	0.49 ± 0.13	1.44 ± 0.16	0.73 ± 0.27
		重度干旱 SD	15.10 ± 0.16	0.53 ± 0.11	1.12 ± 0.07	0.61 ± 0.24
C₄	干旱 Drought	对照 CK	19.70 ± 2.56^a	0.16 ± 0.01^a	6.90 ± 0.65^a	2.90 ± 0.14
		中度干旱 MD	15.21 ± 0.70^a	0.13 ± 0.01^b	5.13 ± 0.23^a	3.02 ± 0.07
		重度干旱 SD	10.82 ± 0.66^b	0.09 ± 0.02^c	3.53 ± 0.26^b	3.09 ± 0.03
	复水 Rehydration	对照 CK	17.21 ± 0.64	0.14 ± 0.01	4.23 ± 0.12	0.79 ± 0.23
		中度干旱 MD	18.40 ± 1.18	0.14 ± 0.03	4.40 ± 0.98	0.91 ± 0.28
		重度干旱 SD	18.90 ± 1.46	0.16 ± 0.02	3.77 ± 0.57	0.76 ± 0.24

功能群 Functional group	时期 Period	处理 Treatment	净光合速率 Net photosynthetic rate (μmol·m^-2·s^-1)	气孔导度 Stomatal conductance (mol·m^-2·s^-1)	蒸腾速率 Transpiration rate (mmol·m^-2·s^-1)	水分利用效率 Water use efficiency (μmol·mmol^-1)
C₃	干旱 Drought	对照 CK	13.60 ± 1.13^a	0.51 ± 0.08^a	17.30 ± 1.48^a	0.82 ± 0.07^a
		中度干旱 MD	10.50 ± 1.05^a	0.43 ± 0.08^a	13.30 ± 1.11^b	0.84 ± 0.12^a
		重度干旱 SD	8.13 ± 1.06^b	0.14 ± 0.02^b	6.29 ± 1.03^c	1.48 ± 0.23^b
	复水 Rehydration	对照 CK	15.90 ± 0.44	0.59 ± 0.09	1.12 ± 0.09	0.85 ± 0.27
		中度干旱 MD	15.90 ± 0.51	0.49 ± 0.13	1.44 ± 0.16	0.73 ± 0.27
		重度干旱 SD	15.10 ± 0.16	0.53 ± 0.11	1.12 ± 0.07	0.61 ± 0.24
C₄	干旱 Drought	对照 CK	19.70 ± 2.56^a	0.16 ± 0.01^a	6.90 ± 0.65^a	2.90 ± 0.14
		中度干旱 MD	15.21 ± 0.70^a	0.13 ± 0.01^b	5.13 ± 0.23^a	3.02 ± 0.07
		重度干旱 SD	10.82 ± 0.66^b	0.09 ± 0.02^c	3.53 ± 0.26^b	3.09 ± 0.03
	复水 Rehydration	对照 CK	17.21 ± 0.64	0.14 ± 0.01	4.23 ± 0.12	0.79 ± 0.23
		中度干旱 MD	18.40 ± 1.18	0.14 ± 0.03	4.40 ± 0.98	0.91 ± 0.28
		重度干旱 SD	18.90 ± 1.46	0.16 ± 0.02	3.77 ± 0.57	0.76 ± 0.24

功能群 Functional group	物种 Species	处理 Treatment	地上生物量 Aboveground biomass (g·pot^-1)	地下生物量 Underground biomass (g·pot^-1)	总生物量 Total biomass (g·pot^-1)	根冠比 Root to shoot ratio	比叶质量 Specific leaf mass (g·m^-2)
C₃	小黑麦 Triticosecale wittmack	对照 CK	1.38 ± 0.07^a	0.72 ± 0.01^a	2.11 ± 0.14^a	0.61 ± 0.03^c	36.48 ± 0.72^a
		中度干旱 MD	0.97 ± 014^b	0.72 ± 0.05^a	1.60 ± 0.11^b	0.76 ± 0.02^b	42.49 ± 1.70^b
		重度干旱 SD	0.59 ± 0.05^c	0.65 ± 0.02^b	1.21 ± 0.06^b	1.09 ± 0.03^a	50.20 ± 0.71^c
	燕麦 Avena sativa	对照 CK	1.03 ± 0.04^a	0.87 ± 0.01^a	2.03 ± 0.17^a	0.62 ± 0.01^b	24.19 ± 1.96^a
		中度干旱 MD	0.83 ± 0.01^b	0.63 ± 0.05^b	1.53 ± 0.04^b	0.74 ± 0.06^b	28.11 ± 0.40^b
		重度干旱 SD	0.43 ± 0.01^c	0.40 ± 0.01^c	0.84 ± 0.05^c	1.08 ± 0.08^a	36.18 ± 1.75^b
	黑麦草 Lolium perenne	对照 CK	0.80 ± 0.03^a	0.56 ± 0.01^a	1.36 ± 0.04^a	0.65 ± 0.03^c	29.98 ± 0.35^a
		中度干旱 MD	0.61 ± 0.01^b	0.45 ± 0.03^b	1.01 ± 0.05^b	0.73 ± 0.02^b	38.14 ± 0.50^b
		重度干旱 SD	0.41 ± 0.02^c	0.37 ± 0.01^c	0.76 ± 0.03^c	0.86 ± 0.11^a	46.83 ± 1.07^c
	普通小麦 Triticum aestivum	对照 CK	0.84 ± 0.05^a	0.24 ± 0.01^a	0.99 ± 0.03^a	0.20 ± 0.01^c	31.66 ± 1.95^a
		中度干旱 MD	0.65 ± 0.02^b	0.21 ± 0.01^b	0.90 ± 0.03^a	0.36 ± 0.02^b	37.01 ± 1.57^b
		重度干旱 SD	0.40 ± 0.02^c	0.19 ± 0.01^b	0.62 ± 0.01^b	0.52 ± 0.01^a	48.87 ± 1.44^b
C₄	狗尾草 Setaria viridis	对照 CK	2.06 ± 0.09^a	0.99 ± 0.03^ab	3.05 ± 0.11^a	0.47 ± 0.01^b	33.87 ± 1.07
		中度干旱 MD	1.50 ± 0.03^b	1.01 ± 0.09^a	2.45 ± 0.02^b	0.73 ± 0.05^a	37.07 ± 0.07
		重度干旱 SD	1.37 ± 0.04^c	0.94 ± 0.02^b	2.30 ± 0.02^b	0.73 ± 0.01^a	38.93 ± 2.31
	水田稗 Echinochloa oryzoides	对照 CK	1.03 ± 0.02^a	0.64 ± 0.01^a	1.65 ± 0.02^a	0.63 ± 0.01^b	25.14 ± 1.07
		中度干旱 MD	0.83 ± 0.06^b	0.68 ± 0.03^a	1.43 ± 0.07^b	0.74 ± 0.01^a	25.70 ± 0.86
		重度干旱 SD	0.72 ± 0.02^b	0.57 ± 0.01^b	1.27 ± 0.02^c	0.82 ± 0.04^a	25.85 ± 0.71
	虎尾草 Chloris virgata	对照 CK	1.42 ± 0.05^a	0.87 ± 0.11^a	2.33 ± 0.13^a	0.49 ± 0.01^b	34.99 ± 0.72
		中度干旱 MD	1.25 ± 0.03^b	0.62 ± 0.01^b	1.79 ± 0.05^b	0.57 ± 0.02^ab	33.63 ± 0.79
		重度干旱 SD	0.80 ± 0.10^c	0.55 ± 0.03^c	1.34 ± 0.05^c	0.78 ± 0.03^a	33.00 ± 0.97

功能群 Functional group	物种 Species	处理 Treatment	地上生物量 Aboveground biomass (g·pot^-1)	地下生物量 Underground biomass (g·pot^-1)	总生物量 Total biomass (g·pot^-1)	根冠比 Root to shoot ratio	比叶质量 Specific leaf mass (g·m^-2)
C₃	小黑麦 Triticosecale wittmack	对照 CK	1.38 ± 0.07^a	0.72 ± 0.01^a	2.11 ± 0.14^a	0.61 ± 0.03^c	36.48 ± 0.72^a
		中度干旱 MD	0.97 ± 014^b	0.72 ± 0.05^a	1.60 ± 0.11^b	0.76 ± 0.02^b	42.49 ± 1.70^b
		重度干旱 SD	0.59 ± 0.05^c	0.65 ± 0.02^b	1.21 ± 0.06^b	1.09 ± 0.03^a	50.20 ± 0.71^c
	燕麦 Avena sativa	对照 CK	1.03 ± 0.04^a	0.87 ± 0.01^a	2.03 ± 0.17^a	0.62 ± 0.01^b	24.19 ± 1.96^a
		中度干旱 MD	0.83 ± 0.01^b	0.63 ± 0.05^b	1.53 ± 0.04^b	0.74 ± 0.06^b	28.11 ± 0.40^b
		重度干旱 SD	0.43 ± 0.01^c	0.40 ± 0.01^c	0.84 ± 0.05^c	1.08 ± 0.08^a	36.18 ± 1.75^b
	黑麦草 Lolium perenne	对照 CK	0.80 ± 0.03^a	0.56 ± 0.01^a	1.36 ± 0.04^a	0.65 ± 0.03^c	29.98 ± 0.35^a
		中度干旱 MD	0.61 ± 0.01^b	0.45 ± 0.03^b	1.01 ± 0.05^b	0.73 ± 0.02^b	38.14 ± 0.50^b
		重度干旱 SD	0.41 ± 0.02^c	0.37 ± 0.01^c	0.76 ± 0.03^c	0.86 ± 0.11^a	46.83 ± 1.07^c
	普通小麦 Triticum aestivum	对照 CK	0.84 ± 0.05^a	0.24 ± 0.01^a	0.99 ± 0.03^a	0.20 ± 0.01^c	31.66 ± 1.95^a
		中度干旱 MD	0.65 ± 0.02^b	0.21 ± 0.01^b	0.90 ± 0.03^a	0.36 ± 0.02^b	37.01 ± 1.57^b
		重度干旱 SD	0.40 ± 0.02^c	0.19 ± 0.01^b	0.62 ± 0.01^b	0.52 ± 0.01^a	48.87 ± 1.44^b
C₄	狗尾草 Setaria viridis	对照 CK	2.06 ± 0.09^a	0.99 ± 0.03^ab	3.05 ± 0.11^a	0.47 ± 0.01^b	33.87 ± 1.07
		中度干旱 MD	1.50 ± 0.03^b	1.01 ± 0.09^a	2.45 ± 0.02^b	0.73 ± 0.05^a	37.07 ± 0.07
		重度干旱 SD	1.37 ± 0.04^c	0.94 ± 0.02^b	2.30 ± 0.02^b	0.73 ± 0.01^a	38.93 ± 2.31
	水田稗 Echinochloa oryzoides	对照 CK	1.03 ± 0.02^a	0.64 ± 0.01^a	1.65 ± 0.02^a	0.63 ± 0.01^b	25.14 ± 1.07
		中度干旱 MD	0.83 ± 0.06^b	0.68 ± 0.03^a	1.43 ± 0.07^b	0.74 ± 0.01^a	25.70 ± 0.86
		重度干旱 SD	0.72 ± 0.02^b	0.57 ± 0.01^b	1.27 ± 0.02^c	0.82 ± 0.04^a	25.85 ± 0.71
	虎尾草 Chloris virgata	对照 CK	1.42 ± 0.05^a	0.87 ± 0.11^a	2.33 ± 0.13^a	0.49 ± 0.01^b	34.99 ± 0.72
		中度干旱 MD	1.25 ± 0.03^b	0.62 ± 0.01^b	1.79 ± 0.05^b	0.57 ± 0.02^ab	33.63 ± 0.79
		重度干旱 SD	0.80 ± 0.10^c	0.55 ± 0.03^c	1.34 ± 0.05^c	0.78 ± 0.03^a	33.00 ± 0.97

功能群 Functional group	时期 Period	处理 Treatment	地上生物量 Aboveground biomass (g·pot^-1)	地下生物量 Underground biomass (g·pot^-1)	总生物量 Total biomass (g·pot^-1)	根冠比 Root to shoot ratio	比叶质量 Specific leaf mass (g·m^-2)
C₃	干旱 Drought	对照 CK	0.96 ± 0.13^a	0.57 ± 0.13	1.53 ± 0.24^a	0.61 ± 0.11	32.01 ± 2.76^b
		中度干旱 MD	0.73 ± 0.09^a	0.48 ± 0.10	1.21 ± 0.17^a	0.65 ± 0.11	36.40 ± 3.15^b
		重度干旱 SD	0.45 ± 0.05^b	0.38 ± 0.08	0.83 ± 0.12^b	0.86 ± 0.14	45.90 ± 3.48^a
	复水 Rehydration	对照 CK	1.45 ± 0.31^a	0.85 ± 0.27^a	2.31 ± 0.54	0.55 ± 0.11	34.41 ± 2.21
		中度干旱 MD	1.31 ± 0.29^a	0.73 ± 0.27^ab	2.05 ± 0.55	0.53 ± 0.10	34.83 ± 2.13
		重度干旱 SD	1.02 ± 0.24^b	0.61 ± 0.24^b	1.63 ± 0.45	0.56 ± 0.13	32.00 ± 1.91
C₄	干旱 Drought	对照 CK	1.52 ± 0.31	0.84 ± 0.13	2.34 ± 0.44	0.57 ± 0.03	31.70 ± 2.83
		中度干旱 MD	1.24 ± 0.22	0.73 ± 0.12	1.97 ± 0.34	0.61 ± 0.04	31.22 ± 2.83
		重度干旱 SD	0.96 ± 0.18	0.71 ± 0.12	1.67 ± 0.31	0.74 ± 0.03	32.43 ± 3.51
	复水 Rehydration	对照 CK	1.48 ± 0.24	0.79 ± 0.23^ab	2.27 ± 0.47	0.52 ± 0.09	37.81 ± 1.33
		中度干旱 MD	1.64 ± 0.41	0.91 ± 0.28^a	2.55 ± 0.68	0.54 ± 0.07	36.92 ± 1.85
		重度干旱 SD	1.48 ± 0.29	0.76 ± 0.24^b	2.24 ± 0.52	0.52 ± 0.09	35.20 ± 0.85