四种不同生活型植物幼苗对喀斯特生境干旱的生理生态适应性

doi:10.3724/SP.J.1258.2011.01070

摘要/Abstract

摘要：

喀斯特石漠化是我国西南喀斯特地区最严重的生态环境问题, 生境干旱是限制该地区植物生长的主要因素之一, 掌握喀斯特植被不同演替阶段不同生活型植物对干旱胁迫的适应策略有助于提高植被恢复的成功率。通过人工模拟4种干旱强度, 测定叶片水势、气体交换、叶绿素荧光、光合色素含量、渗透调节物质浓度、抗氧化酶活性以及生物量, 研究了喀斯特地区4种不同生活型植物幼苗对干旱胁迫的适应策略。这4种植物为常绿灌木火棘(Pyracantha fortuneana)、落叶灌木小果蔷薇(Rosa cymosa)、常绿乔木猴樟(Cinnamomum bodinieri)和落叶乔木圆果化香树(Platycarya longipes)。结果表明: 随着干旱程度的加深, 4种植物幼苗的叶片水势、光合能力、叶绿素含量、生物量增长、叶重比(LMR)、叶面积比(LAR)和比叶面积(SLA)逐渐下降, 而热耗散(NPQ)、类胡萝卜素与叶绿素含量比值、丙二醛含量和根重比(RMR)逐渐上升; 圆果化香树和猴樟的水分利用效率(A_n/g_s)、渗透调节物质浓度和抗氧化酶活性呈先升高后降低的趋势, 而火棘和小果蔷薇的A_n/g_s、脯氨酸含量和超氧化物歧化酶活性呈上升趋势。严重干旱下, 火棘和小果蔷薇幼苗的叶片水势和叶绿素含量下降较少, 具有较高的光合能力和生物量增长, 这主要是由于它们具有较低的SLA和LAR、较高的NPQ和A_n/g_s以及较高的渗透调节能力和抗氧化保护能力。中度干旱下, 猴樟幼苗叶片水势下降很少, LMR和LAR也较高, 脯氨酸含量和抗氧化酶活性非常高。但在严重干旱下, 其叶片水势、LMR、LAR和生物量增长大幅度下降, 最大光化学效率和光合速率也非常低, 渗透调节能力与抗氧化酶活性大幅度下降至正常水平以下。水分好的条件下, 圆果化香树幼苗具有较高的RMR以吸收充足的水分, 具有较高的LAR和叶绿素含量, 保证了生物量的大量积累。然而, 干旱胁迫致使其生物量大幅度下降, 主要是由于LMR、LAR、气体交换和叶绿素含量的大量下降以减少蒸腾面积、水分散失和对光能的吸收。研究结果表明, 火棘、小果蔷薇和猴樟幼苗主要采用耐旱策略, 其中猴樟抗严重干旱的能力较弱; 圆果化香树幼苗对干旱胁迫更为敏感, 主要采取避旱策略。

关键词: 适应策略, 抗氧化酶, 生活型, 石灰岩, 渗透调节, 光合作用, 水分亏缺

Abstract:

Aims Drought stress is one of the most important factors limiting the growth of plants in the harsh karst habitats of southwestern China, especially at the seedling establishment stage. Our objective was to elucidate the adaptive strategies against drought stress of native plants with different growth forms.
Methods We investigated leaf water potential, photosynthetic capacity, pigments, osmotic solutes, antioxidant enzymes, and growth of the seedlings of four plant species under four drought intensities. The species were Pyracantha fortuneana (evergreen shrub), Rosa cymosa (deciduous shrub), Cinnamomum bodinieri (evergreen tree), and Platycarya longipes (deciduous tree).
Important findings As drought stress intensified, leaf water potential, photosynthetic capacity, chlorophylls content, biomass increase, leaf mass ratio (LMR), leaf area ratio (LAR) and specific leaf area (SLA) gradually decreased, while thermal dissipation (NPQ), ratio of carotenoids to chlorophylls, malondialdehyde content and root mass ratio (RMR) increased in the four species. Intrinsic water use efficiency (A_n/g_s), content of osmotic solutes and activity of antioxidant enzymes in C. bodinieri and Platycarya longipes increased under mild and/or moderate drought and decreased under severe drought, while A_n/g_s, proline content and superoxide dismutase activity gradually increased in Pyracantha fortuneana and R. cymosa as drought intensified. Under severe drought, Pyracantha fortuneana and R. cymosa showed smaller decreases of predawn water potential and chlorophylls content and maintained higher photosynthetic capacity and larger percent biomass increase than C. bodinieri and Platycarya longipes, due to lower SLA and LAR, higher A_n/g_s and NPQ and higher capacities of osmotic adjustment and antioxidant protection. Under moderate drought, C. bodinieri exhibited small decrease of predawn water potential and higher LMR and LAR than the deciduous species, and maintained unusually high proline accumulation and high activities of antioxidant enzymes. However, the low maximum quantum efficiency of PSII photochemistry and net assimilation rate, the sharp decreases of water potential, LMR, LAR and biomass and the low capacities of osmotic adjustment and antioxidant protection under severe drought indicated C. bodinieri’s weak tolerance. Under well-watered condition, Platycarya longipes with high RMR showed higher LAR, chlorophylls content and biomass increase than the two shrubs. However, in response to drought stress, Platycarya longipes revealed sharp reduction of biomass due to large drought-induced decreases of gas exchange, LAR, LMR and chlorophylls content. It minimized water loss by both stomatal closure and reducing transpiration leaf area through shedding leaves and also reduced light harvesting by pigments breakdown. These results suggested that Pyracantha fortuneana, R. cymosa and C. bodinieri adopted tolerance strategies against drought stress with C. bodinieri having lower tolerance to severe drought, whereas Platycarya longipes was more sensitive to drought stress and employed avoidance strategies.

Key words: adaptive strategy, antioxidant, growth form, limestone, osmotic adjustment, photosynthesis, water deficit

刘长成, 刘玉国, 郭柯. 四种不同生活型植物幼苗对喀斯特生境干旱的生理生态适应性. 植物生态学报, 2011, 35(10): 1070-1082. DOI: 10.3724/SP.J.1258.2011.01070

LIU Chang-Cheng, LIU Yu-Guo, GUO Ke. Ecophysiological adaptations to drought stress of seedlings of four plant species with different growth forms in karst habitats. Chinese Journal of Plant Ecology, 2011, 35(10): 1070-1082. DOI: 10.3724/SP.J.1258.2011.01070

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链接本文: https://www.plant-ecology.com/CN/10.3724/SP.J.1258.2011.01070

https://www.plant-ecology.com/CN/Y2011/V35/I10/1070

图/表 6

图1 干旱胁迫下4种喀斯特植物幼苗的叶片清晨水势(平均值±标准误差; n = 10)。4种干旱处理: 正常浇水(D1)、轻度干旱(D2)、中度干旱(D3)、严重干旱(D4)。不同的字母代表 4种干旱处理间差异显著(p < 0.05)。

Fig. 1 Predawn water potential of seedlings of four karst plant species under four drought treatments (mean ± SE; n = 10). Four drought treatments: well-watered (D1), mild drought stress (D2), moderate drought stress (D3), severe drought stress (D4). Different letters denote significant differences among four drought treatments (p < 0.05).

图2 干旱胁迫下4种喀斯特植物幼苗的光合速率(An)、气孔导度(gs)、水分利用效率(An/gs)和胞间CO2与大气CO2浓度的比值(Ci/Ca) (平均值±标准误差; n = 20)。4种干旱处理: 正常浇水(D1)、轻度干旱(D2)、中度干旱(D3)、严重干旱(D4)。不同的字母代表四种干旱中处理间差异显著(p < 0.05)。

Fig. 2 Net assimilation rate (An), stomatal conductance (gs), intrinsic water use efficiency (An/gs) and the ratio of intercellular to ambient CO2 (Ci/Ca) of seedlings of four karst plant species under four drought treatments (mean ± SE; n = 20). Four drought treatments: well-watered (D1), mild drought stress (D2), moderate drought stress (D3), severe drought stress (D4). Different letters denote significant differences among four drought treatments (p < 0.05).

图3 干旱胁迫下4种喀斯特植物幼苗的最大光化学效率(Fv/Fm)、电子传递速率(ETR)、光化学淬灭(qP)和非光化学淬灭(NPQ) (平均值±标准误差; n = 20)。4种干旱处理: 正常浇水(D1)、轻度干旱(D2)、中度干旱(D3)、严重干旱(D4)。不同的字母代表四种干旱中处理间差异显著(p < 0.05)。

Fig. 3 The maximum quantum efficiency of PSII photochemistry (Fv/Fm), electron transport rate (ETR), photochemical quenching (qP) and non-photochemical quenching (NPQ) of seedlings of four karst plant species under four drought treatments (mean ± SE; n = 20). Four drought treatments: well-watered (D1), mild drought stress (D2), moderate drought stress (D3), severe drought stress (D4). Different letters denote significant differences among four drought treatments (p < 0.05).

图4 干旱胁迫下4种喀斯特植物幼苗的叶绿素含量(Chl a+b)、类胡萝卜素与叶绿素含量的比值(Car/Chl (a+b))、可溶性糖和脯氨酸含量(平均值±标准误差; n = 3)。4种干旱处理: 正常浇水(D1)、轻度干旱(D2)、中度干旱(D3)、严重干旱(D4)。不同的字母代表四种干旱中处理间差异显著(p < 0.05)。

Fig. 4 Total chlorophylls (Chl a+b), the ratio of carotenoids to total chlorophylls (Car/Chl (a+b)), soluble sugar content and proline content of seedlings of four karst plant species under four drought treatments (mean ± SE; n = 3). Four drought treatments: well-watered (D1), mild drought stress (D2), moderate drought stress (D3), severe drought stress (D4). Different letters denote significant differences among four drought treatments (p < 0.05).

图5 干旱胁迫下4种喀斯特植物幼苗的丙二醛(MDA)含量、超氧化物歧化酶(SOD)、过氧化氢酶(CAT)和过氧化物酶(POD)活性(平均值±标准误差; n = 3)。4种干旱处理: 正常浇水(D1)、轻度干旱(D2)、中度干旱(D3)、严重干旱(D4)。不同的字母代表四种干旱中处理间差异显著(p < 0.05)。

Fig. 5 Malondialdehyde (MDA) content, and activities of superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD) of seedlings of four karst plant species under four drought treatments (mean ± SE; n = 3). Four drought treatments: well-watered (D1), mild drought stress (D2), moderate drought stress (D3), severe drought stress (D4). Different letters denote significant differences among four drought treatments (p < 0.05).

图6 干旱胁迫下4种喀斯特植物幼苗的生物量增长、叶重比(LMR)、茎重比(SMR)、根重比(RMR)、叶面积比(LAR)和比叶面积(SLA) (平均值±标准误差; n = 5)。4种干旱处理: 正常浇水(D1)、轻度干旱(D2)、中度干旱(D3)、严重干旱(D4)。不同的字母代表四种干旱中处理间差异显著(p < 0.05)。

Fig. 6 Biomass increase, leaf mass ratio (LMR), stem mass ratio (SMR), root mass ratio (RMR), leaf area ratio (LAR) and specific leaf area (SLA) of seedlings of four karst plant species under four drought treatments (mean ± SE; n = 5). Four drought treatments: well-watered (D1), mild drought stress (D2), moderate drought stress (D3), severe drought stress (D4). Different letters denote significant differences among four drought treatments (p < 0.05).

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