Elevated CO2 increases shoot growth but not root growth and C:N:P stoichiometry of Suaeda aralocaspica plants

We report on the relationship between growth, partitioning of shoot biomass and hydraulic development of Eucalyptus tereticornis Sm. grown in glasshouses for six months. Close coordination of stem vascular capacity and shoot architecture is vital for survival of eucalypts, especially as developing trees are increasingly subjected to spasmodic droughts and rising atmospheric CO2 levels. Trees were exposed to constant soil moisture deficits in 45 L pots (30–50% below field capacity), while atmospheric CO2 was raised to 700 μL CO2 L–1 in matched glasshouses using a hierarchical, multi-factorial design. Enrichment with CO2 stimulated shoot growth rates for 12–15 weeks in well-watered trees but after six months of CO2 enrichment, shoot biomasses were not significantly heavier (30% stimulation) in ambient conditions. By contrast, constant drought arrested shoot growth after 20 weeks under ambient conditions, whereas elevated CO2 sustained growth in drought and ultimately doubled the shoot biomass relative to ambient conditions. These growth responses were achieved through an enhancement of lateral branching up to 8-fold due to CO2 enrichment. In spite of larger transpiring canopies, CO2 enrichment also improved the daytime water status of leaves of droughted trees. Stem xylem development was highly regulated, with vessels per unit area and cross sectional area of xylem vessels in stems correlated inversely across all treatments. Furthermore, vessel numbers related to the numbers of leaves on lateral branches, broadly supporting predictions arising from Pipe Model Theory that the area of conducting tissue should correlate with leaf area. Diminished water use of trees in drought coincided with a population of narrower xylem vessels, constraining hydraulic capacity of stems. Commensurate with the positive effects of elevated CO2 on growth, development and leaf water relations of droughted trees, the capacity for long-distance water transport also increased.

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High vapour pressure deficit and low soil water availability enhance shoot growth responses of a C4 grass (Panicum coloratum cv. Bambatsi) to CO2 enrichment

Functional Plant Biology ◽

10.1071/pp97054 ◽

1998 ◽

Vol 25 (3) ◽

pp. 287 ◽

Cited By ~ 20

Author(s):

Saman P. Seneweera ◽

Oula Ghannoum ◽

Jann Conroy

Keyword(s):

Soil Water ◽

Elevated Co2 ◽

Vapour Pressure ◽

Shoot Growth ◽

Vapour Pressure Deficit ◽

C4 Grasses ◽

Growth Responses ◽

High Co2 ◽

C4 Grass ◽

Shoot Mass

The hypothesis that shoot growth responses of C4 grasses to elevated CO2 are dependent on shoot water relations was tested using a C4 grass, Panicum coloratum (NAD-ME subtype). Plants were grown for 35 days at CO2 concentrations of 350 or 1000 µL CO2 L-1. Shoot water relations were altered by growing plants in soil which was brought daily to 65, 80 or 100% field capacity (FC) and by maintaining the vapour pressure deficit (VPD) at 0.9 or 2.1 kPa. At 350 µL CO2 L-1, high VPD and lower soil water content depressed shoot dry mass, which declined in parallel at each VPD with decreasing soil water content. The growth depression at high VPD was associated with increased shoot transpiration, whereas at low soil water, leaf water potential was reduced. Elevated CO2 ameliorated the impact of both stresses by decreasing transpiration rates and raising leaf water potential. Consequently, high CO2 approximately doubled shoot mass and leaf length at a VPD of 2.1 kPa and soil water contents of 65 and 80% FC but had no effect on unstressed plants. Water use efficiency was enhanced by elevated CO2 under conditions of stress but this was primarily due to increases in shoot mass. High CO2 had a greater effect on leaf growth parameters than on stem mass. Elevated CO2 increased specific leaf area and leaf area ratio, the latter at high VPD only. We conclude that high CO2 increases shoot growth of C4 grasses by ameliorating the effects of stress induced by either high VPD or low soil moisture. Since these factors limit growth of field-grown C4 grasses, it is likely that their biomass will be enhanced by rising atmospheric CO2 concentrations.

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Root and Shoot Growth Periodicity of Green Ash, Scarlet Oak, Turkish Hazelnut, and Tree Lilac

Journal of the American Society for Horticultural Science ◽

10.21273/jashs.120.2.211 ◽

1995 ◽

Vol 120 (2) ◽

pp. 211-216 ◽

Cited By ~ 22

Author(s):

J. Roger Harris ◽

Nina L. Bassuk ◽

Richard W. Zobel ◽

Thomas H. Whitlow

Keyword(s):

Root Growth ◽

Root Length ◽

Shoot Growth ◽

Lateral Roots ◽

Growth Patterns ◽

Extension Rate ◽

Green Ash ◽

Growth Measurement ◽

Root And Shoot Growth ◽

Growth Periodicity

The objectives of this study were to determine root and shoot growth periodicity for established Fraxinus pennsylvanica Marsh. (green ash), Quercus coccinea Muenchh. (scarlet oak), Corylus colurna L. (Turkish hazelnut), and Syringa reticulata (Blume) Hara `Ivory Silk' (tree lilac) trees and to evaluate three methods of root growth periodicity measurement. Two methods were evaluated using a rhizotron. One method measured the extension rate (RE) ofindividual roots, and the second method measured change in root length (RL) against an observation grid. A third method, using periodic counts of new roots present on minirhizotrons (MR), was also evaluated. RE showed the least variability among individual trees. Shoot growth began before or simultaneously with the beginning of root growth for all species with all root growth measurement methods. All species had concurrent shoot and root growth, and no distinct alternating growth patterns were evident when root growth was measured by RE. Alternating root and shoot growth was evident, however, when root growth was measured by RL and MR. RE measured extension rate of larger diameter lateral roots, RL measured increase in root length of all diameter lateral roots and MR measured new root count of all sizes of lateral and vertical roots. Root growth periodicity patterns differed with the measurement method and the types of roots measured.

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Evaluation of a Substrate-applied Humectant to Mitigate Drought Stress in Young, Container-grown Plants

Journal of Environmental Horticulture ◽

10.24266/0738-2898-33.3.137 ◽

2015 ◽

Vol 33 (3) ◽

pp. 137-141

Author(s):

Bruce R. Roberts ◽

Chris Wolverton ◽

Samantha West

Keyword(s):

Drought Stress ◽

Root Growth ◽

Shoot Growth ◽

Dry Weight ◽

Root:Shoot Ratio ◽

Xylem Water Potential ◽

Bedding Plants ◽

Shoot Dry Weight ◽

Soilless Substrate ◽

Absorbing Roots

The efficacy of treating soilless substrate with a commercial humectant was tested as a means of suppressing drought stress in 4-week-old container-grown Zinnia elegans Jacq. ‘Thumbelina’. The humectant was applied as a substrate amendment at concentrations of 0.0, 0.8, 1.6 and 3.2% by volume prior to withholding irrigation. An untreated, well-watered control was also included. The substrate of treated plants was allowed to dry until the foliage wilted, at which time the plants were harvested and the following measurements taken: number of days to wilt (DTW), xylem water potential (ψx), shoot growth (shoot dry weight, leaf area) and root growth (length, diameter, surface area, volume, dry weight). For drought-stressed plants grown in humectant-treated substrate at concentrations of 1.6 and 3.2%, DTW increased 25 and 33%, respectively. A linear decrease in ψx was observed as the concentration of humectant increased from 0.0 to 3.2%. Linear trends were also noted for both volumetric moisture content (positive) and evapotranspiration (negative) as the concentration of humectant increased. For non-irrigated, untreated plants, stress inhibited shoot growth more than root growth, resulting in a lower root:shoot ratio. For non-irrigated, humectant-treated plants, the length of fine, water-absorbing roots increased linearly as humectant concentration increased from 0.0 to 3.2%. Using humectant-amended substrates may be a management option for mitigating the symptoms of drought stress during the production of container-grown bedding plants such as Z. elegans.

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Root Growth of Avocado is More Sensitive to Salinity than Shoot Growth

Journal of the American Society for Horticultural Science ◽

10.21273/jashs.129.2.0188 ◽

2004 ◽

Vol 129 (2) ◽

pp. 188-192 ◽

Cited By ~ 32

Author(s):

N. Bernstein ◽

A. Meiri ◽

M. Zilberstaine

Keyword(s):

Salt Stress ◽

Root Growth ◽

Biomass Production ◽

Root Elongation ◽

Shoot Growth ◽

Elongation Rate ◽

Persea Americana ◽

Root Growth Inhibition ◽

Leaf Biomass ◽

Volumetric Growth

In most crop species, growth of the shoot is more sensitive to salt stress than root growth. Avocado [Persea americana Mill.] is very sensitive to NaCl stress. Even low concentrations of salt (15 mm) inhibit tree growth and decrease productivity. Observations in experimental orchards have suggested that root growth in avocado might be more restricted by salinity than shoot growth. In the present study, we evaluated quantitatively the inhibitory effects of salt stress on growth of the avocado root in comparison to the shoot. Seedling plants of the West-Indian rootstock `Degania 117' were grown in complete nutrient solution containing 1, 5, 15, or 25 mm NaCl. The threshold NaCl concentration causing root and shoot growth reduction occurred between 5 and 15 mm. At all concentrations, root growth was much more sensitive to salinity than shoot growth. A concentration of 15 mm NaCl, which did not affect the rate of leaf emergence on the plant and decreased leaf biomass production only 10%, induced a 43% reduction in the rate of root elongation and decreased root volumetric growth rate by 33%. Under 25 mm NaCl, leaf biomass production, leaf initiation rate and leaf elongation rate were reduced 19.5%, 12%, and 5%, respectively, while root volumetric growth and root elongation rate were reduced 65% and 75%, respectively. This strong root growth inhibition is expected to influence the whole plant and therefore root growth under salinity should be considered as an important criterion for rootstocks' tolerance to NaCl.

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Yellow lupin (Lupinus luteus) tolerates waterlogging better than narrow-leafed lupin (L. angustifolius) I. Shoot and root growth in a controlled environment

Australian Journal of Agricultural Research ◽

10.1071/ar99073 ◽

2000 ◽

Vol 51 (6) ◽

pp. 701 ◽

Cited By ~ 22

Author(s):

C. L. Davies ◽

D. W. Turner ◽

M. Dracup

Keyword(s):

Root Growth ◽

Western Australia ◽

Shoot Growth ◽

Dry Weight ◽

Lupinus Luteus ◽

Controlled Environment ◽

Yellow Lupin ◽

Legume Crop ◽

Leaf Dry Weight ◽

Better Than

We studied the adaptation of narrow-leafed lupin (Lupinus angustifolius) and yellow lupin (L. luteus) to waterlogging because yellow lupin may have potential as a new legume crop for coarse-textured, acidic, waterlogging-prone areas in Western Australia. In a controlled environment, plants were waterlogged for 14 days at 28 or 56 days after sowing (DAS). Plants were more sensitive when waterlogged from 56 to 70 DAS than from 28 to 42 DAS, root growth was more sensitive than shoot growth, and leaf expansion was more sensitive than leaf dry weight accumulation. Waterlogging reduced the growth of narrow-leafed lupin (60–81%) more than that of yellow lupin (25–56%) and the response was more pronounced 2 weeks after waterlogging ceased than at the end of waterlogging. Waterlogging arrested net root growth in narrow-leafed lupin but not in yellow lupin, so that after 2 weeks of recovery the root dry weight of yellow lupin was the same as that of the control plants but in narrow-leafed lupin it was 62% less than the corresponding control plants. Both species produced equal amounts of hypocotyl root when waterlogged from 28 to 42 DAS but yellow lupin produced much greater amounts than narrow-leafed lupin when waterlogged from 56 to 70 DAS.

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Contribution of the TROLC gene to the regulation of tobacco growth in response to stress factors.

Biomics ◽

10.31301/2221-6197.bmcs.2021-25 ◽

2021 ◽

Vol 13 (3) ◽

pp. 360-367

Author(s):

B.R. Kuluev ◽

Kh.G. Musin ◽

E.A. Baimuhametova

Keyword(s):

Transgenic Plants ◽

Root Growth ◽

Shoot Growth ◽

Growth Parameters ◽

Cadmium Acetate ◽

Stress Factors ◽

Wild Type ◽

Abiotic Stress Factors ◽

Negative Effect ◽

Response To Stress

The trolC gene refers to plast genes that have entered the genome of Nicotiana tabacum as a probable result of horizontal transfer from Agrobacterium rhizogenes. It was shown that the trolC gene is expressed in young tissues of wild type tobacco; however, the physiological functions of the product of this gene remain largely unknown. The aim of our work was to obtain transgenic tobacco plants expressing a fragment of the trolC gene under the control of the 35SCaMV promoter in an antisense orientation and to assess the growth parameters of their roots under the action of abiotic stress factors. For morphometric analysis, 8 lines of transgenic plants were used. The analysis of root growth under the action of sodium chloride (100 mM), cadmium acetate (100 μM) and hypothermia (12°C) was conducted. Transgenic plants were characterized by improved shoot growth parameters under normal conditions. The roots of transgenic plants grew more slowly under normal conditions and under the action of cadmium and hypothermia than in wild type plants. The product of trolC gene has a negative effect on shoot growth, a positive effect on root growth, and also participates in the regulation and maintenance of root growth under the action of cadmium and hypothermia.

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Root Growth of Accolade™ Elm in Structural Soil Under Porous and Nonporous Asphalt After Twelve Years

Arboriculture & Urban Forestry ◽

10.48044/jauf.2019.026 ◽

2019 ◽

Vol 45 (6) ◽

Author(s):

Nina Bassuk ◽

Gary Raffel ◽

Miles Schwartz Sax

Keyword(s):

Root Growth ◽

Tree Growth ◽

Ground Penetrating Radar ◽

Soil Profile ◽

Shoot Growth ◽

Porous Asphalt ◽

Ground Penetrating

Accolade™ Elm trees were planted in CU Structural Soil® overlaid with porous or nonporous asphalt in 2005. At three separate points (2012, 2015, and 2016) over the last twelve years, root densities were measured with Ground Penetrating Radar to a depth of 30 inches (76.2 cm) beneath the asphalt. Roots under the porous asphalt were more numerous and tended to grow deeper in the structural soil profile. Shoot growth was reduced in trees that grew under the nonporous asphalt beginning in the eighth year after planting. CU Structural Soil® is a viable medium for tree growth and stormwater capture when paved with porous asphalt.

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Napropamide Uptake, Transport, and Metabolism in Corn (Zea mays) and Tomato (Lycopersicon esculentum)

Weed Science ◽

10.1017/s0043174500040297 ◽

1981 ◽

Vol 29 (6) ◽

pp. 697-703 ◽

Cited By ~ 10

Author(s):

Michael Barrett ◽

Floyd M. Ashton

Keyword(s):

Zea Mays ◽

Lycopersicon Esculentum ◽

Root Growth ◽

Shoot Growth ◽

Root Tissue ◽

Tomato Root ◽

Corn Roots ◽

Tomato Roots ◽

Absorption Studies ◽

Root And Shoot Growth

Napropamide [2-(α-napthoxy)-N,N-diethylpropionamide] inhibited root and shoot growth in corn (Zea maysL. ‘NC+ 59’) and tomato (Lycopersicon esculentumMill. ‘Niagara VF315’) seedlings. Shoot growth was reduced less than root growth in both species. Corn roots were approximately 10 times more sensitive to napropamide than were tomato roots. Translocation of napropamide from the roots to the shoot of tomato occurred within 0.5 h and followed an apoplastic pattern. Little movement of napropamide from the roots to the shoots occurred in corn. Metabolism of napropamide was not evident in either species during an 8-h exposure. Absorption studies showed that total napropamide levels were 60% higher in corn root tissue than in tomato root tissue. The greater napropamide content in the corn roots was associated with a tightly bound fraction of the total napropamide influx.

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