Influence Root Growth Research Articles

Leaf level response of planted eastern white pine ( Pinus strobus L.) seven years after intensive silvicultural treatments

The present study examines the impact of intensive silvicultural treatments on environmental conditions, leaf level morphology and physiology, and growth of planted eastern white pine ( Pinus strobus L.) saplings and evaluates how silvicultural treatments and the presence of competing vegetation influence the relationships between leaf nitrogen, leaf morphology, and leaf level photosynthetic capacity of saplings. The six silvicultural treatments evaluated consisted of combinations of scarification (removal of entire humus layer), vegetation control (herbicide), and fertilization (slow release fertilizer). Competing vegetation (mainly Populus tremuloides Michx.) had negative impacts on shoot water potential ( Ψ x), leaf nitrogen, leaf mass per unit leaf area (LMA), height, and basal area of 7-year-old saplings. Net CO 2 assimilation rate at light saturation ( A; both on a mass and area basis) and stomatal conductance for water vapor ( g wv) were not significantly influenced by the presence of competing vegetation. The only significant impact of competition on gas exchange variables was to decrease water-use efficiency (both instantaneous and long-term WUE as expressed by carbon isotope discrimination or Δ). Scarification significantly increased predawn Ψ x, height, and basal area of suppressed saplings, and A area, g wv, and LMA of saplings subject to herbicide application. These positive impacts of scarification were attributed to enhanced root growth due to higher soil temperatures. No positive impact of fertilization was observed in either suppressed or open conditions. Leaf nitrogen and LMA were both driving variables for photosynthetic capacity of saplings across all conditions created by silvicultural treatments, but also within both suppressed and open conditions. This suggests that the dependency of the photosynthetic apparatus on leaf nitrogen and LMA occurs whether there is competing vegetation (and/or shade) or not. However, the gradient of light availability under suppressed conditions was accompanied by a gradient of soil temperature due to scarification. It would be pertinent to investigate more fully the interactions between light availability and soil temperature, both influencing root growth and leaf level morphology and physiology of young eastern white pine.

Soil Heterogeneity and Root Distribution of Mature Loblolly Pine Stands in Piedmont Soils

AbstractFactors that influence rooting patterns in mature forest stands are poorly understood. We examined the distribution of loblolly pine (Pinus taeda L.) roots in trench profiles and related rooting to selected soil physical features along a moisture gradient on the Clemson University Experimental Forest, Clemson, SC. Root density was greater on xeric and subxeric sites than on intermediate sites. Root density declined exponentially with soil depth. Fine roots (<4 mm) accounted for 83 to 95% of all roots and averaged 17 fold higher in root channels than in the soil matrix. Root density was also higher along rock‐soil interfaces than in the soil matrix. Soil morphological and physical features, as well as the relative position of the site in the landscape, influence root growth and survival and markedly affect the distribution of roots in mature loblolly pine stands.

Chemical or Air Root-Pruning Containers Improve Carambola, Longan, and Mango Seedling Root Morphology and Initial Root Growth after Transplanting

Abstract Carambola (Averrhoa carambola L.), longan (Dimocarpus longan Lour.), and mango (Mangifera indica L.) nursery transplants were produced in copper-treated, air-root-pruning (only carambola and mango), or untreated conventional plastic containers during 1990 and 1991. Copper treatments did not influence root growth of carambola or mango; but increased total root growth during container production, the proportion of roots in the upper half of the root system, and new root growth after transplanting for longan. Air-root-pruning containers increased the proportion of roots in the upper half of the rootball and new root growth of carambola and mango following transplanting. Copper-treated containers for longan and air-root-pruning containers for carambola and mango effectively stopped root extension growth at the container wall-medium interface.

Substrate Temperatures Influence Root and Shoot Growth of Southern Highbush and Rabbiteye Blueberries

A greenhouse study was conducted to evaluate the influence of substrate temperatures (16, 27, and 38C) on root and shoot growth of six blueberry (Vaccinium spp.) clones (three clones each of two types). Between types, southern highbush (primarily V. corymbosum L.) produced more roots and total growth than rabbiteye (V. ashei Reade). Comparing clones, `Gulfcoast' (southern highbush) was the most vigorous and `Tifblue' (rabbiteye) the least vigorous. Each clone had a negative linear response to substrate temperatures in all growth characteristics. Root and shoot growth was best at 16C. This study indicates that both rabbiteye and southern highbush blueberries would respond favorably to cultural practices that lower soil temperatures during the summer growing season.

Hairy roots of Brassica napus: I. Applied glutamine overcomes the effect of phosphinothricin treatment

Hairy roots of Brassica napus (rape cv. Giant) were produced by cocultivating leaf and cotyledon explants with Agrobacterium rhizogenes strain A4T. The hairy roots grew prolifically on solid and in liquid media. Incorporation of ammonium sulphate or phosphinothricin (PPT) into the media reduced growth. PPT treatment reduced glutamine synthetase (GS) activity and increased the ammonia content of the hairy roots. We have found that PPT treatment also induces a loss of glutamine from the roots and this may influence root growth. To test this we grew hairy roots in a liquid medium containing 10 mM glutamine. This glutamine treatment overcame the PPT induced suppression of growth but also significantly increased GS activity, reduced ammonia accumulation and increased the levels of glutamate and asparagine.

Factors influencing root growth capacity of spruce seedlings: Report on a statistical analysis

Factors influencing root growth capacity of spruce seedlings: Report on a statistical analysis

Factors influencing root growth capacity of spruce seedlings: Case-study description

Canadian Journal of StatisticsVolume 20, Issue 4 p. 483-487 Article Factors influencing root growth capacity of spruce seedlings: Case-study description Wendy Bergerud, Wendy Bergerud Province of British Columbia Ministry of Forests Research Branch 31 Bastion Square Victoria, B.C. V8W 3E7 Consulting Statistician with the B.C. Ministry of Forests Research Branch. This Branch is involved with a wide variety of research problems associated with forestry: problems such as how to grow trees for restocking logged areas and making sure that they continue to grow once planted, how to control the brush in plantations, and how to integrate forestry practices with wildlife and recreational needs.Search for more papers by this author Wendy Bergerud, Wendy Bergerud Province of British Columbia Ministry of Forests Research Branch 31 Bastion Square Victoria, B.C. V8W 3E7 Consulting Statistician with the B.C. Ministry of Forests Research Branch. This Branch is involved with a wide variety of research problems associated with forestry: problems such as how to grow trees for restocking logged areas and making sure that they continue to grow once planted, how to control the brush in plantations, and how to integrate forestry practices with wildlife and recreational needs.Search for more papers by this author First published: December 1992 https://doi.org/10.2307/3315618 AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Volume20, Issue4December 1992Pages 483-487 RelatedInformation

Pepper Seedling Growth Response to Drought Stress and Exogenous Abscisic Acid

ABA and drought stress were evaluated on growth morphology and dry weight of pepper (Capsicum annuum L.) seedlings subjected to continuous watering (CV) or alternate watering (AW) subflotation irrigation. When ABA (10-4m) was sprayed on to leaves 28, 32, or 37 days after seeding (DAS), leaf growth was limited relative to the controls. Root dry weight, basal root count, and diameter decreased in AW compared with CW-treated seedlings. ABA did not influence root growth of the transplants or subsequent total fruit yield. When ABA was applied to leaves at 20,23, or 29 DAS, there was a transient inhibition of leaf weight increase, but root growth was unaffected. Exogenous ABA may have a practical application as a substitute for drought stress to control transplant growth in the nursery. Chemical name used: abscisic acid (ABA).

Tree Root Growth and Development. II. Response to Culture, Management and Planting

Abstract Cultural factors influencing root growth in the landscape or nursery include soil management, irrigation, fertilization, shoot pruning and root pruning. These affect root density, depth of penetration, spread, vertical distribution in the soil profile and mineral uptake. Root morphology varies widely among genera, species and individuals within a species. The distribution, length and weight of roots within the root ball of transplanted field-grown trees can be modified with cultural management practices. Growth of transplanted trees may be affected by these modifications. Root spread diameter increases at a rate of 0.9–2.4 m (36–96 in)/year following planting. From 1 to 10 years is required to replace the pre-transplant root system for trees transplanted from field nurseries. Root system in urban environments can be modified by cultural techniques which direct their growth.

Physiological disturbances in plants caused by air pollutants

SynopsisThe physiological and biochemical features of plants that are responsible for determining susceptibility or tolerance to air pollutants have often proved hard to identify. In recent years, however, there has been new experimental evidence of responses which may be of critical importance. These include (a) changes in stomatal behaviour, affecting plant-water relations, (b) alterations in carbon and nitrogen assimilation and partitioning which can influence root growth, and (c) interference with the processes of winter hardening. Evidence of these changes to physiological processes, and the ways in which responses to pollutants may become more significant to plant survival in the presence of other environmental stresses, are discussed. The longer-term consequences, or secondary responses, such as effects on associations with other organisms, are also briefly reviewed. We have also examined the possibility that ecosystems may be overloaded with inputs of nitrogen from the atmosphere.

Effect of oxygen supply and temperature at the root on the physiology of kiwifruit vines

SummaryA severe leaf disorder currently affects kiwifruit vines (Actinidia deliciosa var. deliciosa) in New Zealand and a number of other countries. The symptoms, which develop in mid‐summer, include interveinal chlorosis, development of necrolic areas on the leaf and eventual leaf death. Field observations strongly indicated the involvement of the root system. The present study investigated the extent to which temperature and oxygen supply at the root influenced the physiology of kiwifruit vines.Maximum root growth occurred at 20 °C, while temperatures in excess of 25 °C reduced growth. Shoot growth was also reduced by root temperatures above 20 °C. No obvious leaf symptoms developed on the vines affected by the high temperatures. Below 20 °C there was a marked reduction in growth with little or no growth occurring at 10 °C. While soil temperature can be expected to influence root growth per se, it would appear unlikely that it directly controls the seasonal pattern of root growth or greatly influences the physiology of the leaf.This study showed kiwifruit vines are not well adapted to tolerate low concentrations of oxygen in their root zone. Growth was substantially reduced when the supply of oxygen to the roots was reduced. The extent of the reduction was proportional to the number of hours per day the vines were without aeration. Root growth was particularly affected. Distinctive leaf symptoms appeared on all oxygen‐stressed vines and included the sudden appearance of large necrotic areas on the older leaves, sometimes preceded by an interveinal chlorosis. Measurement of the porosity of the roots indicated that the average air space between the tightly packed cells accounted for 2% or less of the total root volume. There was no obvious change in root porosity with decreasing oxygen supply or difference between the solution grown vines and vines from the field.Decreasing the supply of oxygen to the roots resulted in rapid reduction in the stomatal conductance of the leaves and the virtual elimination of the diurnal pattern. Associated with the decrease m the stomatal conductance was a marked increase in the maximum daily temperature of the leaves compared to the control vines. The difference between the two treatments increased with time. An estimate of the rate of consumption of oxygen per unit length of root (9.1 × 10−10 mol m−1 s −1) suggests that a mature kiwifruit vine could deplete the oxygen supply in a well aerated soil to an anoxic condition in about 5 hours. The relatively high consumption of oxygen coupled with the low porosity of the roots ensures that even short periods of low concentrations of oxygen in the root zone will seriously affect the physiology and growth of kiwifruit vines. It was concluded that poor aeration of the root system is likely to be a major factor in the incidence of the leaf disorder currently affecting kiwifruit vines in a number of countries.

Root growth potential and shoot activity of northern and southern provenances of 1–0 eastern white pine seedlings grown in a Virginia nursery

Root growth potential and shoot activity were examined from October until April using northern and southern half-sib families of 1–0 eastern white pine (Pinusstrobus L.) seedlings (grown in a Virginia nursery). There were significant differences in root growth potential between northern and southern provenances and this was apparently due to the larger size of seedlings of southern origin. Heritability estimates indicate that root growth potential is under minimal genetic control in 1–0 eastern white pine seedlings. Southern provenances maintained higher shoot activity at the end of the root growth potential test during the autumn months. By April, northern provenances had surpassed southern provenances in shoot activity. Large differences in shoot activity did not result in large root growth potential differences which may indicate that bud dormancy status does not highly influence root growth potential in 1–0 eastern white pine seedlings.

Corn Seedling Root Growth as Influenced by Soil Physical Properties1

AbstractManagement practices often affect soil physical properties adversely thus reducing root growth. In the field difficulty arises in determining which soil physical property is influencing root growth because the factors are not readily separated. The purpose of this study was to examine the effects of isolated soil physical factors on corn (Zea mays L.) seedling growth under controlled conditions. Corn was grown in A horizon material of Groseclose silt loam (clayey, mixed, mesic Typic Hapludult) at four bulk densities (1.10, 1.22, 1.35, and 1.47 Mg/m3), four lower soil moisture levels (0.24, 0.21, 0.18, and 0.15 m3/m3), four higher soil moisture levels (0.24, 0.27, 0.30, and 0.33 m3/m3), and three temperatures (25, 21, and 17°C) in growth chamber experiments. Optimal conditions as indicated by maximum root elongation for corn in Groseclose silt loam occurred with volumetric moisture contents from 0.24 to 0.27 m3/m3, bulk densities <1.22 Mg/m3, and a temperature of approximately 25°C. High bulk density, oxygen stress, low temperature, and water stress all reduced root elongation to some extent. Low temperature had the most dramatic effect. At 6 days corn root length at 21°C was only about 20% of that at 25°C, whereas root length at 17°C was only about 5% of that at 25°C. As bulk density increased, root length decreased. After 4 days high soil moisture stimulated root growth. Root length was not reduced by low soil moisture except at the lowest level (equivalent to a matric potential of −1090 kPa).

Control of Wheat Root Elongation Growth

Pritchard, J., Tomos, A. D. and Wyn Jones, R. G. 1987. Control of wheat root elongation growth. I. Effects of ions on growth rate, wall rheology and cell water relations.—J. exp. Bot. 38: 948-959. The nature of the ions in the bathing medium of hydroponically grown wheat seedlings strongly influenced root growth rate. In 0-5 mol m ~3 CaS04 the growth rate was 32 mm 24 h ~1 (used as 100% control rate). K+ and SO4 ions (10 mol m3) each inhibited extension growth (to about 40% and 70% of the control value respectively). In the absence of K+, CP greatly reduced the inhibition due to SOj. Measurement of tissue plasticity and elasticity in the expanding zone with an Instron-type tensiometer indicated that both were a function of growth rate although relationship of plasticity to growth rate was the steeper and the more pronounced. Turgor pressure at the proximal end of the expanding zone was not correlated to growth, being approximately 0-65 MPa in all treatments. In mature tissue turgor pressure varied with treatment, but was also not related to growth rate. Cell membrane hydraulic conductivity (5 x 10 7 ± -3 ( 10) m s 1 MPa1) was not influenced by the presence of K + . We propose that K+ and SOj influence root growth rates by modulating the rheological properties of the walls of the expanding cell. The physiological significance of these properties is discussed. Key words—Growth, wall extensibility, turgor pressure, wheat roots. Correspondence to: Adran Biocemeq a Gwyddor Pridd, Colea Prifysqol Goqledd Cymru, Banqor, Gwynedd LL57 2 UW, Wales.

Effect of zinc, cadmium and mercury on root elongation of Picea abies (Karst.) seedlings, and the significance of these metals to forest die-back

Inhibition of root elongation was used to assess the toxicity of Zn, Cd and Hg to Picea abies seedlings. The order of toxicity was found to be Hg > Cd > Zn. A comparison of the levels of these metals, shown to inhibit root elongation in nutrient solution, with those in forest soils under stands showing symptoms of die-back, suggests that metal levels in such soils are sufficiently high to influence root growth.

Influence of Trickle Irrigation and Nitrogen Rates to Acer rubrum L.

Water was applied at flow rates of 0, 3.8 and 7.6 liters per hour (0, 1 and 2 gph) and nitrogen (N) was surface applied at 50, 100, 200, and 300 kg/ha (45, 90, 180 and 270 lbs/A) in 1981 and 1982 to Acer rubrum (L.). Tree height, trunk caliper and root dry weight within an AAN specified size were greater with trees grown with 3.8 l/h (1 gph) compared to non-irrigated trees. Tree height and trunk caliper were not affected by N rate. Nitrogen rate influenced root growth. Roots of red maples grown with 3.8 l/h (1 gph) and 200 kg/ha (180 lbs/A) of N were more concentrated under the tree.

Factors affecting shoot proliferation and root initiation in organ cultures of the apple ‘Northern Spy’

Factors affecting the establishment, proliferation and adventitious root initiation of ‘Northern Spy’ are described. Shoot-tips established best in Linsmaier and Skoog medium with 5 μM BAP and 1 μM IBA supplemented with 1 mM phloroglucinol, but after the fourth sub-culture, proliferation was similar in media without phloroglucinol. Shoot proliferation was influenced by cytokinin type and concentration, light level and ex-plant type. Of the cytokinins tested, BAP was superior to zeatin, kinetin and 2iP. Proliferation was better with 10 μM BAP than with 5 or 1 μM BAP, but at 10 μM shoots were dwarfed. Single nodes and basal mass expiants produced significantly more shoots than did shoot-tips. Shoot proliferation was maximum at photon flux densities of 75 μmolm −2s −1. Roots can be readily induced with IBA, but salt concentration and the physical support on which shoot-tips are grown influence both root initiation and growth. Half-strength salts and 1 μM IBA gave best root initiation. With agar, coarse sand, perlite and rotated liquid medium, 90–100% root initiation occurs, but root growth was poor in agar.

Farm management and the function of field crop root systems

Because most farmer-controlled factors influence the growth and function of plant roots, we need to develop root-centered models to describe below-ground plant behavior. A root-centered water extraction model is described. This model estimates water extraction rates from a soil layer in terms of the length of root present, the permeability of the soil-root system, and the difference in water potential between bulk soil and the root xylem in the mid-plane of the soil layer. Changes in xylem water potential resulting from frictional losses as water passes through small vessels is estimated using the Poiseuille-Hagen equation. These potential changes are used to calculate the root xylem water potential at any depth in the profile from the xylem water potential at the land surface. Field data for cotton ( Gossypium hirsutum L.), soybean ( Glycine max L.) and winter wheat ( Triticum aestivum L. em. Thell.) were used to test the model. Measured values of root length density and soil water content over depth and time, field estimates of root-soil system permeability, measured diurnal changes in plant water potential and assumed values of numbers and radii of root xylem vessels were used to estimate water extraction patterns for these three crops for one time in the growing season. Estimates of the total water extraction and its distribution in the profile were in fair agreement with measured values. Principle uncertainties were absence of measurements for numbers and radii of root xylem vessels, questions of lack of homogeneity in field soils for application of a single water release curve to all sampling points in a large plot, and absence of confirming measurements for assessing changes in xylem water potential brought about by friction. When farm managers make decisions on dryland farms, they impact the root system by changing soil physical and chemical properties, the activities of microbes and other organisms, water and nutrient concentrations and distributions. These may influence root growth and function and have an impact on yield. Before models can be used to help farmers make cost-effective decisions, we must learn more about crop root system phenology, environmental effects on root growth and function, and relationships between roots and shoots and between crop roots and their neighboring crop or weed roots. We must also develop models which deal properly with heterogeneity in the landscape, in the crop, and in the soil profile.

Aluminium Induced Magnesium Deficiency in Oats

AbstractIt was the objective to study the effect of Al on Mg uptake by plants, precluding as far as possible the effect of Al on root growth.Oat plants were grown in a complete standard nutrient solution without any differential treatment, in order to obtain a set of plants which did not differ in the size, the morphology and the physiology of the root system. After the first harvest at the beginning of the stem elongation stage 4 different treatments were introduced: pH 5.5‐6.0, pH 5.5‐6.0 without Mg, pH 3.8‐4.1, pH 3.8‐4.1 + 0.3 mmole Al/l. Apart from these variations the composition of the nutrient solution remained unaltered. After another 10 days 2 vessels of each treatment were harvested. The final harvest was 14 days after the beginning of the differential treatments.The growth (in terms of dry matter yield) of neither the shoots nor the roots was adversely affected by the differential treatments, although the plants in the Al and Mg0 treatments showed distinct symptoms of nutritional disorder. The plants in the low and the high pH treatments differed neither in Mg uptakte nor in Mg concentration in the plants. However, the addition of Al to the nutrient solution reduced Mg uptake in the shoots to about 30% of that in the Al0 treatments, while there was a net loss of Mg in the roots in spite of the fact that dry matter increased. This means that net uptake of Mg was less than was translocated to the shoot during the period of differential treatments. With no Al in the nutrient solution the Mg concentration in the shoots declined by 3–8% between the first and the final harvest, whereas it increased by 22–35% in the roots. If, however, Al was added to the nutrient solution the Mg concentration dropped by 46% in the shoots and 70% in the roots. With the exception of Ca in the roots, the differential treatments had no effect on the uptake and concentration of Ca, K and P in the plants.In terms of dry matter the differential treatments did not influence root growth and it was concluded that Al had a direct effect on Mg uptake by either inactivating or competing for uptake sites or carriers.

Physical Factors Influencing Soil Strength and Root Growth1

AbstractSoil compaction is a major factor which influences root growth and crop yields. Studies were conducted to determine the influence of different factors on mechanical impedance and to determine the influence of mechanical impedance and other soil factors on root growth. Regression models for dependent variables, soil strength and root growth, vs. the independent variables, soil type, soil depth, clay content, bulk density, voids, and water content were computed using the maximum R2 improvement by stepwise regression. The models for soil strength and root growth varied with soil type, soil depth, and/or clay content. The soils used were a Miles fine sandy loam, Udic Paleustalf and an Abilene clay loam, Pachic Argiustoll. Soil strength for both soils studied and at all depths was influenced by bulk density, voids, and clay content. The overall equational models accounted for 75% of the variability in soil strength and 76% of the variability in root growth. Root growth in both soils and at all depths was significantly influenced by soil strength, volumetric water content, voids, and clay content. The critical strength in bars, defined as the probe pressure at which root elongation stopped, was a function of % clay. The critical strength ranged from 60 to 70 bars in coarsetextured to 25 bars in clay soils. These data provide a better understanding of the influence of mechanical impedance on root growth, and a basis for determining the need for use of deep tillage to minimize the adverse effects of excessive soil strength or compaction.