The plant environment: light and water
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This chapter first describes the control of gas exchange (CO2, O2 and water vapour) by the plant, and the structure and functions of stomata. The mechanisms that enable plants to detect lack of light are outlined, and shade tolerators and shade avoiders compared. The problems for plants posed by water stress, and the physical and biochemical adaptations that enable them to grow in dry conditions, notably C-4 and crassulacean acid metabolism, are described. The value of different physical adaptations for conserving water largely depends on the conditions in which a plant is growing and the combination of modifications it possesses. The chapter discusses the adaptation of plants to saline conditions, which is followed by a survey of how plants deal with excess water leading to a discussion on aquatic plants. Finally, advice is given on watering practice and choosing garden plants able to cope with drought.Keywords:
Water Stress
Terrestrial plant
• Whether photosynthesis is limited during water stress and recovery because of diffusive or biochemical factors is still open to debate, and apparent contradictions appear when various studies on species with different growth forms are compared. • Ten Mediterranean species, representing different growth forms, were subjected to different levels of water stress, the most severe followed by rewatering. A quantitative limitation analysis was applied to estimate the effects of water stress on stomatal (SL), mesophyll conductance (MCL) and biochemical limitations (BL). • Results confirmed a general pattern of photosynthetic response to water stress among C3 plants when stomatal conductance (gs) is used as a reference parameter. As gs values decreased from a maximum to approx. 0.05 mol H2O m−2 s−1, the total photosynthetic limitation rose from 0 to approx. 70%, and this was caused by a progressive increase of both SL and MCL limitations, while BL remained negligible. When lower values of gs were achieved (total photosynthetic limitation increased from 70 to 100%), the contribution of SL declined, while MCL still increased and BL contributed significantly (20–50%) to the total limitation. • Photosynthetic recovery of severely stressed plants after rewatering showed a dominant role of MCL, irrespective of the degree of photosynthesis recovery.
Stomatal Conductance
Water Stress
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Water Stress
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This experiment was carried out on the potted plants of maize. Three different maize varieties (Shendan 10, Yedan13 and Danyu13) were chosen as experimental materials. This paper compared the effects of different water stress intensity on leaf photosynthesis of different drought -resistant maize hybrids. The results indicated that the photosynthetic rate of maize leaf under water stress went down with the increasing of water stress, and the photosynthetic rate decreased obviously under severe water stress.
Water Stress
Drought stress
Water Use Efficiency
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The influences of water stress on citrus photosynthesis charateristic and cell ultra-structure were systematically studied by using P.trifoliata(L)Raf.and C.sinensis S.as materials.The results showed that the water stress significantly affected net photosynthetic rate(Pn),the transpiration rate(Tr) and stoma cond(Gc) and damaged root,leaf and chloroplast ultra-structure.The damaged degree of ultra-structure was increased by water stress.Under water stress,photosynthesis turned out to be restrained as a result of the cooperation of stoma and non-stoma mechanism;when photosynthesis decreased sharply and the cells were damaged seriously,it was the critical time to irrigate in citrus production.
Water Stress
Stoma (medicine)
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Terrestrial plant
Terrestrial ecosystem
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Water Stress
Crassulaceae
Drought stress
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Stable carbon isotope ratios (δ(13) C) of terrestrial plants are employed across a diverse range of applications in environmental and plant sciences; however, the kind of information that is desired from the δ(13) C signal often differs. At the extremes, it ranges between purely environmental and purely biological. Here, we review environmental drivers of variation in carbon isotope discrimination (Δ) in terrestrial plants, and the biological processes that can either damp or amplify the response. For C3 plants, where Δ is primarily controlled by the ratio of intercellular to ambient CO2 concentrations (ci /ca ), coordination between stomatal conductance and photosynthesis and leaf area adjustment tends to constrain the potential environmentally driven range of Δ. For C4 plants, variation in bundle-sheath leakiness to CO2 can either damp or amplify the effects of ci /ca on Δ. For plants with crassulacean acid metabolism (CAM), Δ varies over a relatively large range as a function of the proportion of daytime to night-time CO2 fixation. This range can be substantially broadened by environmental effects on Δ when carbon uptake takes place primarily during the day. The effective use of Δ across its full range of applications will require a holistic view of the interplay between environmental control and physiological modulation of the environmental signal.
Terrestrial plant
Stomatal Conductance
Carbon fixation
Carbon fibers
Total inorganic carbon
Environmental change
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Photosynthetic inducement was done in one year old,normally growing avocado tree,the effects of water stress on intensity of photosynthesis and relative dynamic changes of photosynthetic pigments was determined under 500 μmol·m -2 ·s -1 .The results indicated:Its photosynthesis dropped clearly with stress intensified.Carotene dropped first,then did chlorophyll a,but chlorphyll b content increased constantly.H 2O 2 increased greatly then it had a decline trend.
Water Stress
Photosynthetic pigment
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Water Stress
Drought stress
Carbon fibers
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