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高温干旱对髯毛箬竹的叶和细根的生理生态影响
李伟成1,2, 盛海燕3, 高贵宾1, 温星1, 田新立1
1. 国家林业局竹子研究开发中心, 浙江省竹子高效加工重点实验室, 浙江 杭州 310012;2. 西南林业大学生命科学学院, 云南 昆明 650224;3. 杭州环境保护科学研究院, 浙江 杭州 310005
摘要:
为了解全球变暖及其导致的高温干旱气候对地被竹生长产生的影响,通过模拟自然高温干旱条件,以髯毛箬竹为研究对象,分析其叶片气体交换、细根和叶片水势、抗氧化酶等生理生态反应过程与高温干旱的关系.结果表明:①不同高温干旱条件对髯毛箬竹的影响不同,对照组中常温条件下植株的光合速率为(7.141±0.072)μmol/(m2·s),高温可明显提升蒸腾速率和气孔导度,极端高温条件下表现为非气孔限制因素导致光合速率〔(4.898±0.395)μmol/(m2·s)下降〕,并且收窄光合日进程的变幅;②中度干旱、高温+中度干旱、极端高温+中度干旱的条件下,光合速率的降低是由气孔限制因素导致;③重度干旱、高温+重度干旱、极端高温+重度干旱的环境将严重影响植株生理进程,高温加剧这一进程,具体表现为蒸腾速率、光合速率、气孔导度和水分利用效率显著下降;④对照组、高温组和极端高温组的细根水势谷值下降范围分别为(-0.111±0.033)~(-0.961±0.086)、(-0.173±0.060)~(-0.970±0.072)和(-0.304±0.061)~(-1.225±0.166) MPa,降幅比成熟叶片强烈;⑤高温和干旱对细根、成熟叶片3种抗氧化酶活性的影响一致,细根SOD活性大于成熟叶片,而CAT和POD活性则相反,因此,细根是髯毛箬竹适应高温干旱环境的重要器官,水分吸收器官比蒸腾器官敏感.研究显示,髯毛箬竹具有较好的抗高温和抗旱能力,一定范围内的高温和干旱能提升其叶片、细根的生理生态适应能力,特别是复合条件下,高温与干旱对其生长表现出协同作用,极端高温+中度干旱并不威胁其生存,高温、中度干旱及高温+中度干旱有利于驯化栽培,甚至在一定程度上能促进其生长;重度干旱则使植株叶片气体交换、叶片和细根的水分生理进程受损,不适宜长期重度干旱的环境,高温使这种损伤更加严重.
关键词:  复合条件  地被竹  气体交换  水势  抗氧化酶
DOI:10.13198/j.issn.1001-6929.2017.03.57
分类号:X173;S718.4
基金项目:浙江省自然科学基金项目(LY14C030008);浙江省科技计划项目(2016F50008)
Impact of Drought, Heat, and Their Combination on the Eco-Physiological Characteristics of Leaves and Fine Roots in Dwarf Bamboo (Indocalamus barbatus)
LI Weicheng1,2, SHENG Haiyan3, GAO Guibin1, WEN Xing1, TIAN Xinli1
1. Key Laboratory of High Efficient Processing of Bamboo of Zhejiang Province, China National Bamboo Research Center, Hangzhou 310012, China;2. College of Life Sciences, Southwest Forestry University, Kunming 650224, China;3. Hangzhou Environmental Protection Science Institute, Hangzhou 310005, China
Abstract:
Drought and high temperature are two main stress factors limiting plant productivity, and often occur simultaneously in nature. To determine the effects of high temperature and drought on plant development and productivity, we investigated the effects of abiotic stress on the growth and quality of dwarf bamboo (Indocalamus barbatus). Specifically, we examined the relationships between simulated stress conditions (high temperature and drought) and eco-physiological processes (leaf gas exchange, water potential of leaves and fine roots, and the antioxidant enzymesystem) in dwarf bamboo. We simulated natural high temperature and drought through heating, dehydrating, and rehydrating processes, using the following three treatment groups:control group (control, moderate drought, and severe drought), high temperature group (high temperature, high temperature+moderate drought, and high temperature + severe drought), and extreme heat group (extreme heat, extreme heat + moderate drought, and extreme heat + severe drought).Our results indicated that the responses of I. barbatus varied significantly under the different simulated temperature and drought conditions. The photosynthetic rate of control plants under normal temperature (7-28℃) and normal soil water content (37.86%±5.95%) was (7.141±0.072) μmol/m2·s. High temperature (30-35℃) significantly increased stomatal conductance and the transpiration rate. Under extreme heat (35-40℃), non-stomatal-limiting factors led to a decrease in photosynthetic rate, which minimized diurnal variations in photosynthesis. Under drought conditions (soil water content 27.95%±2.64%) and its combined treatments with temperature, stomatal-limiting factors led to a decrease in photosynthetic rate. Severe drought (soil water content 18.25%±1.73%)and its combined treatments with temperature markedly affected physiological processes, and high temperature intensified this effect further, due to significant decreases in transpiration, photosynthesis, stomatal conductance, and water-use efficiency. The water potentials of fine roots in the control, high temperature, and extreme heat groups were (-0.111±0.033) to (-0.961±0.086), (-0.173±0.060) to (-0.970±0.072), and (-0.304±0.061) to (-1.225±0.166)MPa, respectively. The water potential of fine roots decreased more markedly than that of mature leaves. The influences of high temperature to three antioxidant enzymes in the fine roots and mature leaves were similartothat of drought stress. The superoxide dismutaseactivity of fine roots was higher than that of mature leaves, whereas in contrast the activities of catalaseand peroxidase were higher in mature leaves. We accordingly conclude that the water potential and antioxidant enzyme activities of leaves and fine roots are useful indicators for estimating the performance of dwarf bamboo under stress conditions. In addition, the absorbing organ (fine root) is more sensitive than the transpiration organ (leaf), and the fine roots in I. barbatus are important tissues for adapting to high temperature and drought conditions. Dwarf bamboo plants showed good tolerance to high temperature and drought stress. Within a certain range of high temperature and drought, dwarf bamboo triggered stress response mechanisms and enhanced antioxidant enzyme activity, particularly under combined treatments. High temperature and drought had no negative effects on growth, and extreme heat + moderate drought did not affect plant health. High temperature and moderate drought, individually and in combination, were found to be favorable for domestication and cultivation. Severe drought decreased leaf gas exchange, and affected leaf and fine root physiological processes, whereas high temperature aggravated the damage caused by drought. On the basis of these results, we conclude that dwarf bamboo is not suitable for growth in regions that experience extreme drought conditions.
Key words:  combined conditions  dwarf bamboo  gas exchange  water potential  antioxidant enzymes