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梭梭根系内水分再分配验证及其对根系寿命的影响
朱丽
学位类型硕士
导师唐立松
2016
学位授予单位中国科学院大学
学位授予地点北京
学位专业植物生态学
关键词土壤含水量 同化枝水势 水分再分配作用 分根装置 根长 细根寿命
摘要水分再分配作用主要是指根际区不同部位土壤间与植物根系间水势差下的运移过程。夜间弱蒸腾作用下,具有水分再分配作用的根系能够从湿润土层中吸收水分,而后将水分运输并释放至干燥土壤层中,使干燥土层的水分有效性得到改善。水分再分配作用提升的这部分水除用于植物本身的需求之外,也可为相邻植物所共享。通过这种水分调节方式能够有效缓解植物的干旱胁迫。本研究通过调控夜间植物蒸腾,以控制植物根系内水分再分配发生的条件,利用上下分根方法及根系观测技术,设置控制处理(仅接受白天自然光照),夜间光照处理(接受24小时光照),加水及夜间光照处理(接受24小时光照+加水)对梭梭根系是否存在水分再分配作用进行了验证,并进一步研究了水分再分配对梭梭自身生理形态、细根寿命及对相邻当年生梭梭苗生长的影响。主要得到如下结果: 结果表明: 1)处理51d后,控制处理梭梭黎明前及正午同化枝水势分别为-2.06及-3.1Mpa,而夜间光照处理分别为-2.9及-3.7Mpa,且控制处理、夜间光照处理、加水及夜间光照处理梭梭上管部分根水势分别为-3.6、-5.2及-3.1Mpa;夜间弱蒸腾作用下,控制处理的梭梭发生了水分再分配作用,帮助干土层中根系获取一定程度的水分补偿。2)控制处理与加水及夜间光照处理的梭梭蒸腾速率分别为6.3及6.8 g·m-2 h-1,均大于夜间光照处理的4.1 g·m-2 h-1,且控制处理和加水及夜间光照处理的梭梭最大净光合速率也较夜间光照处理高,三组处理的梭梭最大净光合速率分别是23.7、17.8及22.4μmol·m-2·s-1。由此说明,水分再分配作用促进梭梭蒸腾及光合作用。3)控制处理与加水及夜间光照处理梭梭地上部分生物量显著高于夜间光照处理,不同处理的梭梭地下部分总生物量、上管地下部分生物量及上管比根长的大小关系均为加水及夜间光照处理>控制处理>夜间光照处理,表明水分再分配作用增加梭梭地上及地下部分的碳分配,成为改变光合产物分配重要因素之一。4)控制处理及夜间光照处理的梭梭上管部分根系寿命中位值分别是36d及24d,夜间的水分再分配作用能够延长干旱土层中的细根寿命。5)梭梭夜间的水分再分配作用所释放的水分提高了其冠下当年生梭梭的生存能力,控制处理的当年生梭梭苗根水势较高于夜间光照处理,且光合作用能力也得到提高。 本研究表明,梭梭具有显著的根内水分再分配作用,在夜间,根系吸收湿润土层中的水分并释放至上层干燥土层中以缓解低水分可利用条件下的水分亏缺,同时,水分再分配作用的发生可促进植物蒸腾及光合速率,延长干土层中细根寿命,促进了植物生长,并增加了冠下当年生梭梭幼苗的存活。
其他摘要Water redistribution within root system can mitigate root drought stress during the dry season. Plant internal redistribution of water from regions of high soil moisture to roots in dry soil occurs during periods of low evaporative demand. Hydraulic redistribution of the water is used by the plant itself also adjacent plants as sharing, through this way of water regulation alleviated the drought soil plant water stress. According to the conditions of Hydraulic redistribution, we conducted a split-root pot cultivation experiment to test the effects of root hydraulic redistribution for H. ammodendron, and observed the root dynamics by minirhizotron method. Considering the occurring of hydraulic redistribution in the low evaporative demand, we measured a series of growth, water physiological and root dynamic characteristics of plant in wet and dry split root zone of pot under three treatments: control (C); 24h light + supplemental water (LW); and 24 h light only (L). The results are:1)After 51 days of treatments, the predawn and midday leaf water potential of plant in control were -2.1 and -3.1Mpa, but for the light treatment, that were -2.9 and -3.68Mpa; the root water potential of the dry soil zone (the upper tube) in control 、light treatment and light and water addition treatment were -3.6、-5.2 and -3.1Mpa; This result indicated that water potential of roots in dry soil zone in control partly recovered at next day predawn due to the hydraulic redistribution at night. 2) The transpiration rates of the control and the light and water addition treatments were 6.3 and 6.8 g·m-2 h-1, there both were higher than 4.1 g·m-2 h-1 of the light treatment. Moreover, the maximum net pohotosynthesitic rates of the control and the light and water addition treatment were larger than the light treatment, they were 23.7、17.8 and 22.4μmol·m-2·s-1, which suggests that the root internal hydraulic redistribution protects the deterioration of plant photosynthetic physiological activities during draught occurring. 3) The aboveground biomass under light treatment was lower in compared to it in the control and light and water addition treatment. The root dry weight in dry soil zone only, the root dry weight of the whole plant and the specific root length (SRL) showed significant differences among treatments, following the rank: LW>C>L. 4) The median root lifespan of the dry soil zone of the plants in the control and the light treatments are 36 and 24days. That to say Hydraulic redistribution can prolong the life of fine roots of dry soil, improve the ability to survive in drought environment, moreover, soil volumetric water content have bigger influence on the fine root life span, determines the length of the fine root lifespan to some extent. 5) Hydraulic redistribution of the H.ammodendron can improve the survivability of the young H.ammodendron, in a certain period of time, the control treatments’ young H.ammodendron processing high water potential, and the photosynthesis ability were improved. In sum, our study observed the effects of hydraulic redistribution on water potential and photosynthetic characteristics in H. ammodendron, which proves that hydraulic redistribution can protect roots of desert shrub in surface soil being damaged by soil temporal draught and maintain a healthy physiological activity.
学科领域植物生态学
语种中文
文献类型学位论文
条目标识符http://ir.xjlas.org/handle/365004/14737
专题研究系统_荒漠环境研究室
作者单位中科院新疆生态与地理研究所
推荐引用方式
GB/T 7714
朱丽. 梭梭根系内水分再分配验证及其对根系寿命的影响[D]. 北京. 中国科学院大学,2016.
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