Whole-Plant Responses to Drought

1986 ◽  
Vol 13 (1) ◽  
pp. 127 ◽  
Author(s):  
ED Schulze
Keyword(s):  
Gas Exchange ◽  
Water Status ◽  
Carbon Assimilation ◽  
Water Shortage ◽  
Root Tip ◽  
Plant Responses ◽  
Root Shoot Ratio ◽  
Whole Plant ◽  
Plant Level ◽  
Stomatal Functioning

The partitioning of carbon and interactions which cause limitations on gas exchange and growth under conditions of a limited supply of water and nutrients are discussed. Possible mechanisms of effects of air humidity on stomatal functioning and carbon assimilation are described. Also, it is shown that stomata respond to a signal from the root when the soil dries out prior to leaf wilting. Stomatal conductance determines canopy transpiration if the aerodynamic boundary layer resistance is low, such as in trees. Water shortage significantly affects extension growth and the root-shoot ratio at the whole- plant level. But experiments with xylem-tapping mistletoes show that stem growth can also be promoted by the presence of the mistletoe even when there is no apparent signal from the subtending shoot except the flow in the stem xylem. It appears that the internal plant water status may not affect gas exchange and carbon partitioning unless the plant fails to maintain a flow of water through the leaf epidermis and root tip.

scholarly journals Gas exchange at whole plant level shows that a less conservative water use is linked to a higher performance in three ecologically distinct pine species

2018 ◽  
Vol 13 (4) ◽  
pp. 045004 ◽  
Author(s):  
D Salazar-Tortosa ◽  
J Castro ◽  
R Rubio de Casas ◽  
B Viñegla ◽  
E P Sánchez-Cañete ◽  
...  
Keyword(s):  
Gas Exchange ◽  
Water Use ◽  
Whole Plant ◽  
Plant Level ◽  
Pine Species

scholarly journals Phosphorus Mobilizing Enzymes of Alnus-Associated Ectomycorrhizal Fungi in an Alaskan Boreal Floodplain

Forests ◽  
2019 ◽  
Vol 10 (7) ◽  
pp. 554 ◽  
Author(s):  
Roger W. Ruess ◽  
Michaela M. Swanson ◽  
Knut Kielland ◽  
Jack W. McFarland ◽  
Karl D. Olson ◽  
...  
Keyword(s):  
Acid Phosphatase ◽  
Ectomycorrhizal Fungi ◽  
Boreal Forests ◽  
Coniferous Forest ◽  
Root Tip ◽  
P Availability ◽  
Soil P ◽  
Whole Plant ◽  
Tightly Coupled ◽  
Plant Level

Because of its high phosphorus (P) demands, it is likely that the abundance, distribution, and N-fixing capacity of Alnus in boreal forests are tightly coupled with P availability and the mobilization and uptake of soil P via ectomycorrhizal fungi (EMF). We examined whether Alnus shifts EMF communities in coordination with increasingly more complex organic P forms across a 200-year-old successional sequence along the Tanana River in interior Alaska. Root-tip activities of acid phosphatase, phosphodiesterase, and phytase of A. tenuifolia-associated EMF were positively intercorrelated but did not change in a predictable manner across the shrub, to hardwood to coniferous forest successional sequence. Approximately half of all Alnus roots were colonized by Alnicola and Tomentella taxa, and ordination analysis indicated that the EMF community on Alnus is a relatively distinct, host-specific group. Despite differences in the activities of the two Alnus dominants to mobilize acid phosphatase and phosphodiesterase, the root-tip activities of P-mobilizing enzymes of the Alnus-EMF community were not dramatically different from other co-occurring boreal plant hosts. This suggests that if Alnus has a greater influence on P cycling than other plant functional types, additional factors influencing P mobilization and uptake at the root and/or whole-plant level must be involved.

scholarly journals Gas exchange, biomass and non-structural carbohydrates dynamics in vines under combined drought and biotic stress

2019 ◽  
Vol 19 (1) ◽  
Author(s):  
Tadeja Savi ◽  
Almudena García González ◽  
Jose Carlos Herrera ◽  
Astrid Forneck
Keyword(s):  
Biotic Stress ◽  
Carbon Metabolism ◽  
Water Status ◽  
Water Shortage ◽  
Sink Strength ◽  
Negative Effects ◽  
Whole Plant ◽  
Leaf Level ◽  
Effects Of Drought ◽  
Near Future

Abstract Background Intensity of drought stress and pest attacks is forecasted to increase in the near future posing a serious threat to natural and agricultural ecosystems. Knowledge on potential effects of a combined abiotic-biotic stress on whole-plant physiology is lacking. We monitored the water status and carbon metabolism of a vine rootstock with or without scion subjected to water shortening and/or infestation with the sucking insect phylloxera (Daktulosphaira vitifoliae Fitch). We measured non-structural carbohydrates and biomass of different plant organs to assess the stress-induced responses at the root, stem, and leaf level. Effects of watering on root infestation were also addressed. Results Higher root infestation was observed in drought-stressed plants compared to well-watered. The drought had a significant impact on most of the measured functional traits. Phylloxera further influenced vines water and carbon metabolism and enforced the sink strength of the roots by stimulating photosynthates translocation. The insect induced carbon depletion, reprogramed vine development, while preventing biomass compensation. A synergic effect of biotic-abiotic stress could be detected in several physiological and morphological traits. Conclusions Our results indicate that events of water shortage favour insects’ feeding damage and increase the abundance of root nodosities. Root phylloxera infestation imposes a considerable stress to the plants which might exacerbate the negative effects of drought.

Whole-Plant Responses to Salinity

1986 ◽  
Vol 13 (1) ◽  
pp. 143 ◽  
Author(s):  
R Munns ◽  
A Termaat
Keyword(s):  
Root Growth ◽  
Leaf Growth ◽  
Water Status ◽  
Leaf Expansion ◽  
Saline Soils ◽  
Plant Responses ◽  
Short Term ◽  
Whole Plant ◽  
Short Term Exposure

This paper discusses whole-plant responses to salinity in order to answer the question of what process limits growth of non-halophytes in saline soils. Leaf growth is more sensitive to salinity than root growth, so we focus on the process or processes that might limit leaf expansion. Effects of short-term exposure (days) are considered separately from long-term exposure (weeks to years). The answer in the short term is probably the water status of the root and we suggest that a message from the root is regulating leaf expansion. The answer to what limits growth in the long term may be the maximum salt concentration tolerated by the fully expanded leaves of the shoot; if the rate of leaf death approaches the rate of new leaf expansion, the photosynthetic area will eventually become too low to support continued growth.

scholarly journals Oscillatory Transpiration May Complicate Stomatal Conductance and Gas-exchange Measurements

HortScience ◽  
1994 ◽  
Vol 29 (6) ◽  
pp. 693-694 ◽  
Author(s):  
Mary Ann Rose ◽  
Mark A. Rose
Keyword(s):  
Steady State ◽  
Stomatal Conductance ◽  
Gas Exchange ◽  
Heat Balance ◽  
Sap Flow ◽  
Closed Loop ◽  
Random Noise ◽  
Plant Responses ◽  
Whole Plant ◽  
Plant Sap

A closed-loop photosynthesis system and a heat-balance sap-flow gauge independently confirmed oscillatory transpiration in a greenhouse-grown Rosa hybrids L. Repetitive sampling revealed 60-minute synchronized oscillations in CO2-exchange rate, stomatal conductance, and whole-plant sap-flow rate. To avoid confusing cyclical plant responses with random noise in measurement, we suggest that gas-exchange protocols begin with frequent, repetitive measurements to determine whether transpiration is stable or oscillating. Single measurements of individual plants would be justified only when transpiration is steady state.

scholarly journals Strategies to Apply Water-Deficit Stress: Similarities and Disparities at the Whole Plant Metabolism Level in Medicago truncatula

2021 ◽  
Vol 22 (6) ◽  
pp. 2813
Author(s):  
Verónica Castañeda ◽  
Esther M. González
Keyword(s):  
Drought Stress ◽  
Water Deficit ◽  
Stress Responses ◽  
Carbon Metabolism ◽  
Crop Productivity ◽  
Invertase Activity ◽  
Water Deficit Stress ◽  
Plant Responses ◽  
Whole Plant ◽  
Plant Level

Water-deficit stresses such as drought and salinity are the most important factors limiting crop productivity. Hence, understanding the plant responses to these stresses is key for the improvement of their tolerance and yield. In this study M. truncatula plants were subjected to 250 mM NaCl as well as reduced irrigation (No-W) and 250 g/L polyethylene glycol (PEG)-6000 to induce salinity and drought stress, respectively, provoking a drop to −1.7 MPa in leaf water potential. The whole plant physiology and metabolism was explored by characterizing the stress responses at root, phloem sap and leaf organ level. PEG treatment led to some typical responses of plants to drought stress, but in addition to PEG uptake, an important impairment of nutrient uptake and a different regulation of carbon metabolism could be observed compared to No-W plants. No-W plants showed an important redistribution of antioxidants and assimilates to the root tissue, with a distinctive increase in root proline degradation and alkaline invertase activity. On the contrary, salinity provoked an increase in leaf starch and isocitrate dehydrogenase activity, suggesting key roles in the plant response to this stress. Overall, results suggest higher protection of salt-stressed shoots and non-irrigated roots through different mechanisms, including the regulation of proline and carbon metabolism, while discarding PEG as safe mimicker of drought. This raises the need to understand the effect at the whole plant level of the different strategies employed to apply water-deficit stress.

scholarly journals THE EFFECT OF TEMPERATURE ON CARBON GAIN IN ALSTROEMERIA

HortScience ◽  
1992 ◽  
Vol 27 (6) ◽  
pp. 649e-649
Author(s):  
E.D. Leonardos ◽  
M.J. Tsujita ◽  
B. Grodzinski ◽  
T.J. Blom
Keyword(s):  
Gas Exchange ◽  
Dark Respiration ◽  
Leaf Gas Exchange ◽  
Carbon Assimilation ◽  
Net Photosynthesis ◽  
Stomatal Resistance ◽  
Effect Of Temperature ◽  
Carbon Gain ◽  
Leaf Transpiration ◽  
Whole Plant

Leaf and whole plant gas exchange (net photosynthesis Pn, dark respiration Dr, transpiration Tr, and resistance R) of `Jacqueline' Alstroemeria, grown in pots inside a greenhouse, were measured under lab conditions using an openflow and a semi-closed system respectively. Temperature responses of apical fully expanded leaves, on flowering and non-flowering shoots, showed an optimum range for net photosynthesis (Pn) from 15 to 20 °C. Above 25 °C Pn dropped considerably as temperature increased. Leaf transpiration rates over the same range of temperature showed a similar decrease, indicating that low leaf Pn rates at higher temperatures were due in part to increased stomatal resistance. Whole plant photosynthetic response to temperature was similar to that of leaf gas exchange. The optimum temperature range for whole plant Pn was from 12 to 17 °C. These results show that moderately low temperatures are essential for carbon assimilation and efficient water use in Alstroemeria. Temperature interactions with other environmental factors will also be presented in models describing Pn rates as a function of irradiance, CO2 concentration, and temperature.

scholarly journals Roots of Lucerne Seedlings are More Resilient to a Water Deficit than Leaves or Stems

Agronomy ◽  
2019 ◽  
Vol 9 (3) ◽  
pp. 123 ◽  
Author(s):  
Yong-Zhong Luo ◽  
Hui Liu ◽  
Guijun Yan ◽  
Guang Li ◽  
Neil Turner
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Water Status ◽  
Critical Role ◽  
Water Shortage ◽  
Root Shoot Ratio ◽  
Relative Water ◽  
Rainout Shelter ◽  
Proline Concentration

Drought is one of the most harmful environmental stresses affecting the physiological, biochemical processes and growth of plants. Lucerne or alfalfa (Medicago sativa L.), one of the most popular pasture species in arid and semi-arid regions, plays a critical role in sustaining agricultural systems in many areas of the world. In order to evaluate the effect of water shortage on water status, biomass distribution and proline content, the relative water content (RWC), biomass and proline concentration in the leaves, stems and roots of lucerne seedlings under three different water regimes were studied in pots under a rainout shelter. The results showed that after water was withheld, the RWC of the different organs decreased significantly; at the same soil water content, the leaf RWC was higher than that of the stem and root. The biomass of the leaves, stems and roots were all reduced by water stress, while the root–shoot ratio increased indicating that the roots were less affected than the leaves and stems. Proline concentration increased with decreasing soil water content with the leaf proline concentration increasing more than that of stems and roots. These results indicate that roots of lucerne seedlings show greater resilience to water deficits than shoots.

scholarly journals Mulching of Ornamental Trees: Effects on Growth and Physiology

2008 ◽  
Vol 34 (3) ◽  
pp. 157-162
Author(s):  
Francesco Ferrini ◽  
Alessio Fini ◽  
Piero Frangi ◽  
Gabriele Amoroso
Keyword(s):  
Gas Exchange ◽  
Tree Growth ◽  
Leaf Gas Exchange ◽  
Carbon Assimilation ◽  
Pine Bark ◽  
First Year ◽  
Trunk Diameter ◽  
Whole Plant ◽  
Growth Differences ◽  
Ornamental Trees

Two organic mulching materials applied to newly planted Tilia × europaea and Aesculus × carnea trees were evaluated for effects on tree growth and physiology. Both mulches were efficient in maintaining a cleared area around newly planted trees, although pine bark was more durable than coarse compost from mixed green material. Trees mulched with compost generally had greater height, trunk diameter, and current-year shoot growth. Differences were more evident in the first year in Aesculus and in the second year in Tilia. Mulching with compost increased carbon assimilation of linden leaves in 2005 when compared with pine bark and chemical weeding. Both mulching materials increased transpiration of horsechestnut in 2005. Little effect on gas exchange was found in 2006 in both species. However, because mulched trees were larger with longer shoots, whole plant leaf gas exchange was probably greater. Mulching had very limited effects on chlorophyll fluorescence. Results of this project have shown that mulching materials applied around trees after planting can positively affect tree growth without significantly affecting tree physiology.

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