The position of localized soil compaction determines root and subsequent shoot growth responses

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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Biological studies of soils in paired old and new land sites growing sugarcane

Australian Journal of Experimental Agriculture ◽

10.1071/ea96137 ◽

1997 ◽

Vol 37 (4) ◽

pp. 451 ◽

Cited By ~ 11

Author(s):

B. L. Blair ◽

R. C. Magarey ◽

J. I. Bull ◽

E. J. Johnson

Keyword(s):

Root Growth ◽

Shoot Growth ◽

Major Contributor ◽

Growth Responses ◽

Biological Community ◽

Root Pathogens ◽

Biological Studies ◽

Growth Constraints ◽

Growth Differences

Summary. The growth of sugarcane in soils from land monocultured with sugarcane, and from land which had either never been cropped with sugarcane, or just recently cropped, was compared under glasshouse conditions. In general, cane growth in new land soils was greater than in monocultured soil (shoot growth 7.4%, root growth 21.4%). Responses to soil pasteurisation were investigated in some soils and were greater in monocultured soils suggesting that root growth constraints were larger in the monocultured soil (210% response in monocultured soils v. 64% in new land soils). Assays for sugarcane root pathogens suggested that Pachymetra chaunorhiza was a major contributor to the old/new land growth responses, but it is unlikely that Pythium spp. were factors in the growth differences. Monitoring of other groups of organisms in soil from one site suggested that sugarcane monoculture may affect populations in the broader biological community.

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Low temperature effects on growth and physiology specific to a "grass-clump" dwarf wheat hybrid

Canadian Journal of Botany ◽

10.1139/b72-035 ◽

1972 ◽

Vol 50 (2) ◽

pp. 253-261 ◽

Cited By ~ 4

Author(s):

J. D. Mahon ◽

D. T. Canvin

Keyword(s):

Low Temperature ◽

Shoot Growth ◽

Growth Habit ◽

Temperature Response ◽

Dry Weight ◽

Growth Responses ◽

Meristematic Region ◽

Meristematic Activity ◽

Dwarf Wheat ◽

Induced Changes

The growth habit of "grass-clump" dwarf wheat plants can be affected by extremely short 16° treatments if given repeatedly. To localize the earliest growth responses in plants of one such hybrid (Mql × KF 1), the temperature sensitivity of plants of different ages, and the earliest temperature-induced changes in growth, development, and shoot physiology were investigated and compared with the responses of normal wheat plants.Mql × KF 1 plants growing at 26° responded to progressively shorter 16° treatments as they aged and plants exposed to 16° after 10 days growth at 26° were unable to recover from low temperature treatments of 3–5 days duration. Although shoot growth (as dry weight) of Mql × KF 1 stopped abruptly after 7 days at 16°, root growth (as dry weight) continued for at least 15 days. The rates of CO2 and water vapor exchange in individual leaves responded to low temperature similarly in both the dwarf and normal plants and did not markedly decrease until after 4 days at 16°. The most rapid low temperature response specific to Mql × KF 1 plants was cessation in primary tiller development immediately after the beginning of 16° exposure. It is proposed that the primary 16° effect is on the shoot meristematic region and that other changes in growth and physiology result from the lack of meristematic activity in the young growing region.

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Interaction with ethylene: changing views on the role of abscisic acid in root and shoot growth responses to water stress

Plant Cell & Environment ◽

10.1046/j.1365-3040.2002.00798.x ◽

2002 ◽

Vol 25 (2) ◽

pp. 211-222 ◽

Cited By ~ 260

Author(s):

R. E. Sharp

Keyword(s):

Abscisic Acid ◽

Water Stress ◽

Shoot Growth ◽

Growth Responses ◽

Root And Shoot Growth

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Root and shoot growth in safflower as affected by soil compaction

Australian Journal of Crop Science ◽

10.21475/ajcs.20.14.09.p2466 ◽

2020 ◽

pp. 1443-1448

Author(s):

Caroline Beal Montiel ◽

Deonir Secco ◽

Araceli Ciotti Marins ◽

Luiz Antônio Zanão Junior ◽

Jeikson Rafael Deggerone ◽

...

Keyword(s):

Root Growth ◽

Crop Yield ◽

Soil Compaction ◽

Shoot Growth ◽

Soil Bulk Density ◽

Carthamus Tinctorius ◽

Field Conditions ◽

Compacted Soils ◽

Tillage Practices ◽

Root And Shoot Growth

Soil compaction, induced by no-tillage practices, can negatively impact soil properties important for plant growth. Compacted soils can restrict root growth depth, resulting in reduced crop yield. Although safflower (Carthamus tinctorius) has a deep root system, yield may still be affected by soil compaction. Therefore, this study aimed to evaluate safflower root and shoot growth when submitted to soil compaction in an Oxisol soil under controlled (greenhouse) and field conditions. Five soil bulk density measures were performed in a greenhouse (1.1, 1.2, 1.3, 1.4 and 1.5 Mg m–3). Four compaction levels (established by the number of passes of a farm tractor: 0, 1, 3, and 5 passes consecutively) were performed to evaluate the effect of soil compaction in the field. Root and shoot growth were measured after harvesting the plants. Safflower root growth was reduced when soil compaction increased from 1.1 to 1.5 Mg m–3 under controlled (greenhouse) conditions. In field conditions, we observed a decrease in root length, and fresh and dry matter in roots and shoots of safflower as the soil compaction increased to 5P (1.28 Mg m–3). The results of our study suggest safflower root and shoot growth can be impacted by soil compaction which could affect crop yield.

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EFFECTS OF IRRIGATION FREQUENCY ON PLANT GROWTH AND NUTRIENT LEVELS OF PINE BARK MEDIA

HortScience ◽

10.21273/hortsci.25.8.849c ◽

1990 ◽

Vol 25 (8) ◽

pp. 849c-849

Author(s):

T.E. Bilderback

Keyword(s):

Plant Growth ◽

Shoot Growth ◽

Chemical Properties ◽

Dry Weight ◽

Pine Bark ◽

Growth Responses ◽

Irrigation Frequency ◽

Foliar Tissue ◽

Physical And Chemical ◽

And Chemical Properties

Ilex × `Nellie R. Stevens' holly, Rhododendron sp. `Hinodegeri' azalea and Pyracantha coccinea, scarlet firethorn rooted cuttings were potted in • 3.81 containers. Irrigation was applied by Dram rings daily, or every 2,4,or 6 days. Approximately 1000 ml of water were applied at each irrigation. Three container media, including pine bark, and pine bark amended with either Terra-Sorb AG synthetic moisture extender incorporated at 1.2 kg/m3 or Aqua-Gro G wetting agent incorporated at 0.9 kg/m3 plus monthly drenches of 700 ml of 2500 ppm Aqua-Gro L were compared for physical and chemical properties and plant growth responses. Decreasing irrigation decreased pH, increased nutrient leachate levels, and increased foliar tissue levels of N,P,K,Ca,and Fe in holly and azalea. Pyracantha top and root dry weight was reduced at 4 and 6 day irrigation intervals, holly top growth was reduced by 6 day and azalea had greatest shoot growth at 2 day irrigation and was reduced by other irrigation frequencies. Top growth of all 3 species and root growth of pyracantha was reduced in the pine bark treatment.

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Physiological and Growth Responses to Irrigation of a Newly Established Hedgerow Olive Orchard

HortScience ◽

10.21273/hortsci.45.5.809 ◽

2010 ◽

Vol 45 (5) ◽

pp. 809-814 ◽

Cited By ~ 9

Author(s):

Maria Gomez-del-Campo

Keyword(s):

Shoot Growth ◽

Irrigation Management ◽

Irrigation Treatment ◽

Maximum Growth ◽

Growth Responses ◽

Canopy Development ◽

Olive Orchard ◽

The Third ◽

Canopy Volume ◽

Second Year

Olive production in the first few years after planting depends on how the canopy covers the hedgerow and develops flowers. Therefore, optimum irrigation management should look for the minimum amount of water required for maximum growth and bud initiation. The response of a young hedgerow olive orchard to different irrigation strategies was recorded for 3 years after planting in 2003. Observations included stem water potential (Ψstem), leaf conductance (gl), shoot and trunk growth, canopy development, and flowering. During the first year, olives received 74 mm of irrigation. During the second and third years, three irrigation treatments (T2, T3, and T4) were scaled back from a control (T1) that was irrigated to maintain soil close to water-holding capacity. T1 received 56 and 106 mm of irrigation in the second and third years, respectively. Treatments T2, T3, and T4 received 82%, 64%, and 46% of the water applied to T1 in the second year and 76%, 72%, and 29% in the third year of growth, respectively. Trees in T1 displayed different physiological and growth behaviors between years. Ψstem, gl, and shoot growth were 131%, 31%, and 56% lower in the third than in the second year, respectively. Irrigation treatment had no significant effect on evaluated parameters in the second year, except on Ψstem in T4 that fell below that of the other treatments in late September. In the third year, shoot growth, trunk diameter, and leaf area density in T4 decreased 52%, 13%, and 31% compared with T1, respectively. Nevertheless, external surface area and canopy volume were not significantly affected by irrigation treatment. The start of flowering, recorded in the third and fourth years, was not significantly affected by the irrigation received in previous years. Because water stress did not advance flowering, maximum growth should be the main objective in irrigation management of young olive orchards. No differences were observed between T3 and T1 in any of the vegetative, canopy development, or inflorescence parameters recorded, although Ψstem and gl were significantly lower in T3. During the second and third years, T3 can be considered the most efficient irrigation treatment with 36 and 76 mm of irrigation for each year, respectively.

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