Total Root Area Research Articles

Nitrate Uptake of Seedling and Mature Kentucky Bluegrass Plants

Understanding the relationship between seedling nitrate uptake rate (NUR) and mature plant NUR will benefit the selection of turfgrass cultivars for high NUR. Seedling NUR as affected by initial mowing is particularly important during turfgrass establishment. The primary objectives of this study were to determine NUR of individual Kentucky bluegrass (Poa pratensis L.) seedlings, to correlate seedling morphological characteristics with NUR, and to ascertain the relationship between seedling NUR and mature plant NUR. Thirty days after seeding, roots of seedlings were placed individually in a polystyrene cup filled with 2 mL of a nutrient solution containing 0.6 mM nitrate, which was replaced at 24‐h intervals for 20 d. After the total leaf and total root length and area were determined, each seedling was planted in silica sand and maintained as a miniature turf for five additional months before NUR was determined in a 130‐mL growth vessel. Seedling NUR was 10 to 60 nmol h−1 per seedling, decreased sharply to <10 nmol h−1 per seedling following the first clipping to remove 1/3 of the leaf blades by length. One week after the first clipping, NUR gradually increased to levels above 10 nmol h−1 per seedling. After seedlings were placed in deionized water for 24 h, NUR during the subsequent 24 h was stimulated, but the magnitude of stimulation differed among cultivars. We found significant among‐cultivar and within‐cultivar differences in seedling NUR, and significant and positive correlations between seedling NUR and seedling size. At the whole plant level, the correlation between seedling NUR and mature plant NUR was positive but generally not significant at P = 0.05.

Sod establishment and turfgrass growth as affected by urea–formaldehyde resin foam soil amendment

Urea–formaldehyde resin foam (UFRF) has recently been introduced as a soil amendment for turfgrass culture. A field study was performed to evaluate the impact of UFRF on soil physical and chemical properties, sod establishment and turfgrass shoot and root growth. Treatments included a non-amended, sandy loam soil and the same soil amended with UFRF at a rate of 20% (v/v) incorporated into the upper 0.1 m of the substrate. Physical and chemical analyses of the two substrates involved the determination of bulk density, total porosity, air-filled porosity at 0.4 m, moisture release curve, pH and electrical conductivity. Turfgrass growth was determined through several measurements that included shoot growth rate, root growth rate and monitoring of three root architecture parameters namely, total root length, total root area and mean root diameter. Turfgrass establishment was evaluated by measuring the vertical force applied to detach the sod from the substrate. UFRF amendment did not influence pH and EC and provided minimal alterations (non-significant) in soil physical properties by slightly increasing total porosity, easily available water and air-filled porosity, and by reducing bulk density. The impact of UFRF amendment improved cumulative clipping yield in five sampling dates but root growth and sod establishment rate were better than the control only on one sampling date. There appears to be limited benefit in amending soil with UFRF.

Nitrogen nutrition of hedged stock plants of Loblolly Pine. II. Influence of carbohydrate and nitrogen status on adventitious rooting of stem cuttings

Hedged stock plants of four full-sib families [27-2 × 27-5, 27-3× 27-1, 27-2 × 27-1, and 27-6 × 27-1 (designated B, G, R, andW)] of loblolly pine (Pinus taeda L.) were fertilizeddailywith a complete nutrient solution containing N at either 10, 25, 40, 55, or 70mg·L−1. May (spring softwood), July(summersoftwood), and January (winter hardwood) terminal stem cuttings were taken fortissue analysis and rooting studies. Spring cuttings rooted in the highestpercentages (59.5%), followed by winter (40.5%), and summer (34.7%). Maximumrooting for spring (70.0%), summer (48.6%), and winter (55.6%) occurred withcuttings taken from hedges that received N at 55mg·L−1. Genetic differences among familieswere evident as families G and W rooted in greater percentages at lower appliedN rates and family B was the best rooting family at the highest applied N rate.When internal N levels were considered families G and W also rooted best at lowinternal N levels, while family B was the best rooting family at high internalNlevels. Neither total nonstructural carbohydrates (TNC) nor any of severalspecific carbohydrates were correlated with rooting and an optimal TNC : Nratiofor rooting was not found. Root counts generally increased with increases inapplied N. Root number was weakly correlated with TNC (R = 0.29, P ≤0.01) and several specific sugars, but was not correlated with internal N.Totalroot dry weight, total root length, and total root area responded similarly.

Nutrient Requirements for Lettuce Transplants Using a Floatation Irrigation System. I. Phosphorus

Several levels of P were supplied via floatation irrigation to `South Bay' lettuce (Lactuca sativa L.) transplants to determine the optimum P concentration necessary. Plants were propagated by floating flats (ebb and flow system) in a nutrient solution containing P at either 0, 15, 30, 45, or 60 mg·L-1 in summer and fall experiments, and either 0, 15, 30, 60, or 90 mg·L-1 P in a factorial combination with 60 or 100 mg·L-1 N in a winter experiment. Adding more than 15 mg·L-1 P had minimal effect on growth. Transplants produced with 0 P grew poorly, regardless of the level of N applied. Nitrogen at 100 mg·L-1 improved the response of shoot growth to any level of P, but adversely affected root growth compared with N applied at 60 mg·L-1. In general, relative growth rate was improved, while net assimilation rate was reduced at all levels of P. High-quality transplants had a root to shoot ratio of about 0.25, total root lengths between 276 and 306 cm, and total root area between 26 and 30 cm3 in a 10.9-cm3 cell volume. Only 30% of the plants produced without P could be pulled from the transplant flats, whereas 90% could be pulled when P was added. Pretransplant P hastened maturity and increased lettuce head weight at harvest in the field. This work suggested that at least 15 mg·L-1 P, supplied via floatation irrigation to a peat + vermiculite mix, was required to produce a transplant with sufficient roots for ease of pulling, rapid field establishment, and earlier harvest.

Cinética de absorção de amônio e crescimento radicular das cultivares de arroz Agulha e Bico Ganga

Este trabalho teve por objetivo avaliar, em dois estádios de desenvolvimento, o crescimento do sistema radicular e a cinética de absorção de amônio das cultivares de arroz Agulha e Bico Ganga, procedentes do Estado do Maranhão. As plantas (25 e 50 dias de idade) cresceram em casa de vegetação, emsolução nutritiva, com quatro níveis de N (20, 40, 60 e 80 mg L-1). Os valores de Vmáx, K M e Cmín foram determinados empregando-se um processo gráfico-matemático. A cultivar Bico Ganga apre-sentou maiores valores de Vmáx e menores de Cmín, aos 25 e 50 dias de idade, nos níveis de 20 e 40 mg L-1 de N, enquanto em altos níveis de N (60 e 80 mg L-1), os maiores valores de Vmáx e menores de Cmín ocorreram na cultivar Agulha. Tanto aos 25 quanto aos 50 dias, a Bico Ganga apresentou maior área radicular, maior produção de matéria fresca e seca de raiz e parte aérea, e maior eficiência de acumulação de N e síntese de proteína na parte aérea. Esses resultados sugerem que a Bico Ganga, por ser uma cultivar local mais antiga que a Agulha, estaria melhor adaptada ao estresse nutricional em ambientes tropicais.

Quantification of common root rot symptoms in resistant and susceptible barley by image analysis

A series of tests were carried out to determine the effect of common root rot, caused by Cochliobolus sativus, on root growth and discolouration in the moderately resistant cv. Bonanza and the susceptible cv. Gateway of barley. An image analyser was used to quantify the growth and discolouration (mean intensity) of the roots and the subcrown internode (SCI) of individual plants. The plants were also visually rated for root rot severity and their root dry weight was determined. In the absence of disease, no differences in root discolouration or growth were observed between the two barley cultivars. In plants grown in naturally infested soil, visual root rot ratings and mean intensity values indicated that the SCls of Bonanza were less discoloured than those of cv. Gateway. In cv. Gateway, higher levels of disease were usually associated with a smaller root system than in cv. Bonanza, but the effect was significant (P < 0.01) only in the first experiment. The root system of cv. Gateway had lower (P > 0.05) mean intensity values (i.e., darker) than those of cv. Bonanza in the first experiment. Seedling emergence of cv. Gateway was lower in naturally infested soil than in fumigated soil, but this was not evident in cv. Bonanza. There was a strong inverse relationship between the mean intensity and visual rating of the SCI and a positive association between total root area as measured using image analysis and root weight. Image analysis also determined that in the severe root rot category, plants of cv. Gateway had SCIs that were more discoloured than those of cv. Bonanza. Discolouration of the SCI of root rot susceptible barley appeared to adversely influence the growth and discolouration of the root system, but this effect was not always significant.

Effet de la contrainte mécanique sur le système racinaire nodal et séminal du maïs

Hydroponic axenic culture conditions, in which the physical culture support of root growth consists of glass beads, are necessary to study physiological processes such as root exudation or absorption. The effects of the mechanical constraint induced by glass beads on the architectural evolution of the root system of young maize plants were examined. A reduction in length of all roots (seminal and nodal), an increase in seminal root diameter and a modification of order 2 root branching were observed. The root biomass was not affected (except for 16-day-old plants) but the total root area was reduced. The shoot growth was significantly decreased by the mechanical constraint.

Phosphorus Requirements for Lettuce Transplant Growth Using a Flotation Irrigation System

Phosphorus applied at frequent rates via the flotation irrigation system affected growth of both roots and shoots of lettuce transplants grown with a flotation irrigation system. After an initial P addition of 15 mg·L–1, further P additions up to 90 mg·L–1 P resulted in a minimal growth response. Transplants produced with 0 P had similar poor growth, regardless of the amount of N applied. Nitrogen at 100 mg·L–1 improved the response of shoot growth to any level of P, but adversely affected root growth compared to N at 60 mg·L–1. Quality transplants had a root to shoot ratio of ≈0.25, total root lengths between 276 and 306 cm, and total root area between 26 and 30 cm2 in a 10.9-cm3 cell volume. Only 30% of the plants produced with 0 P could be pulled from the transplant flats, compared to ≈90% pulling success with added P. All pretransplant P treatments had a similar effect of increasing head mass at harvest time, and in reducing time to maturity regardless of production season. At transplanting, plants produced with transplant P were larger than those produced with no transplant P. Thus, at least 15 mg·L–1, supplied every 2 days via flotation irrigation, is recommended for production of high quality lettuce transplants in a peat+vermiculite media containing low concentrations of water extractable P.

Nitrogen Nutrition of Containerized Cupressus arizonica var. glabra ‘Carolina Sapphire’

Abstract Rooted stem cuttings of ‘Carolina Sapphire’ smooth Arizona cypress [Cupressus arizonica var. glabra (Sudw.) Little ‘Carolina Sapphire’] grown in calcined clay in 3.8 liter (#1) containers were fertilized daily for 16 weeks with a complete nutrient solution containing 0, 20, 40, 80 or 160 mg N/liter supplied as ammonium nitrate. Plant heights and stem diameters were unaffected by N rate suggesting that a daily nutrient application of 20 mg N/liter was adequate for maximizing growth. Nitrogen fertilization increased heights and stem diameters by 71% and 56%, respectively, compared to the nontreated controls (0 mg N/liter). Even though shoot growth was unaffected by increasing N levels, foliage N concentration was positively correlated (r = 0.75, P &amp;lt; 0.0001) to N levels. As N concentration increased, total root area and total root length increased quadratically. Nitrogen fertilization increased root area and root length 119% and 108%, respectively, compared to the nontreated controls. Phosphorus concentration of shoots increased quadratically with increasing N levels. Nitrogen rate failed to affect K concentration of shoots. Shoot Ca and Mg concentrations decreased with increasing N levels.

Short and Long-Term Effects of Treeshelters on the Root and Stem Growth of Ornamental Trees

Short-term (aerated solution culture and container nursery) and long-term (landscape) experiments were conducted to study the effect of treeshelters on the root and shoot growth of several ornamental trees {Sequoia sempervirens (D. Don) Endl., Quercus lobata Nee, Quercus agrifolia Nee, Lagerstroemia indica L. 'Watermelon Red', Ginkgo biloba L, Platanus racemosa Nutt., Fraxinus latifolia Benth. and Populus euamericana cv. Giacometti). In general, plants grown in treeshelters were taller and some had reduced caliper growth. Treeshelters reduced top dry mass of F. latifolia, P. racemosa, Q. agrifolia, Q. lobata and P. euamericana and also reduced root dry mass, root:shoot ratio, total root length and total root area for all species/cultivars except Q. agrifolia. The results are explained on the basis of the microenvironment in/ around treeshelters, photosynthetic partitioning and immobilization of plants growing in shelters. Management challenges and potential usefulness of treeshelters in landscape transplanting are also discussed.

Marigold Growth in Six-packs following Transplanting from Plugs at Several Stages of Development

Root and shoot development in Marigold `Little Devil Flame' was studied after being grown for varying lengths of time in 392-count plugs before transplanting to six-pack cells. Seedlings were grown for 0, 5, 10, 15, 20, and 25 days before transplanting to six-packs. All plants were measured at day 25. There was no significant difference in total root length, area and dry weight per plant or in leaf area and shoot dry weight per plant for seedlings transplanted from 0 to 15 days. Both total root dry weight and total shoot dry weight of seedlings transplanted on day 20 was reduced by 32% compared to seedlings that were not transplanted. Total root dry weight of seedlings transplanted at day 25 was reduced by 60% while total shoot dry weight of seedlings was reduced by 56% from those not transplanted. In a separate experiment, the growth rate of seedlings grown in plugs was sigmoidal (r2 = 0.98). Growth rate was significantly reduced between 20 and 25 days in the plug. These results suggest that root restriction in the plug may be a factor in the reduction of seedling growth following transplanting.

Effects of Drought and Flooding on Root Anatomy in Four Tropical Forage Grasses

Seasonal drought and flooding severely limit pasture growth in savannas, although tropical grasses show broad variation in their tolerance to these water stresses. In this study we analyzed and compared the responses in morphology and anatomy of the roots of four important perennial C4 forage grass species to short-term flooding and moderate drought under controlled conditions. The plants studied were the dryland bunchgrasses Andropogon gayanus and Hyparrhenia rufa and the wetland stoloniferous Echinochloa polystachya and Brachiaria mutica. The responses to flooding were more conspicuous than those to drought, and all species were able to alter their root form and structure under flooding. The most evident response was the development of aerenchymatous tissue in the root cortex, which was proportionally highest in H. rufa. The wetland grasses already had constitutively high proportions of aerenchyma tissue in the cortex, which changed little with waterlogging, up to 40%-49% of total transverse root area. Andropogon gayanus developed the least aerenchyma space in the cortex and was the most affected by flooding. Other effects of flooding included root dimorphism and suberization of both exodermis and endodermis cells in all grasses.

Rooting `Yoshino' Cryptomeria Stem Cuttings as Influenced by Growth Stage, Branch Order, and IBA Treatment

Stem cuttings of `Yoshino' Japanese cedar [Cryptomeria japonica (L.f.) D. Don `Yoshino'], consisting of tips (terminal 20 cm) of first-order laterals, distal halves (terminal 10 cm) of tips of first-order laterals, and proximal halves (basal 10 cm) of tips of first-order laterals, or tips (terminal 10 cm) of second-order laterals, were taken on four dates that represented four growth stages (softwood, semi-hardwood, hardwood, and pre-budbreak). The cuttings were treated with 0, 3000, 6000, or 9000 mg IBA/liter. Branch order affected all rooting measurements at each growth stage. Regardless of growth stage, tips of and proximal halves of first-order laterals containing lignified wood had the highest percent rooting, root count, total root length, root area, and root dry weight. Hardwood tips of and semi-hardwood proximal halves of first-order laterals exhibited the highest overall rooting (87%), followed by softwood proximal halves of first-order laterals (78%). Rooting of distal halves of first-order laterals and tips of second-order laterals never exceeded 55% and 34%, respectively, at any growth stage. IBA treatment influenced percent rooting, root count, total root length, root area, and root dry weight of semi-hardwood, hardwood, and pre-budbreak cuttings, except for root dry weight of semi-hardwood cuttings. IBA had no affect on softwood cuttings. Chemical name used: 1H-indole-3-butyric acid (IBA).

Effects of Seed Priming on Plug Production of Coreopsis lanceolata and Echinacea purpurea

Abstract Seeds of Coreopsis lanceolata (coreopsis) and Echinacea purpurea (purple coneflower) were primed to determine whether improved plug production of these herbaceous perennials would result. Experiments were conducted at two locations: Texas A&amp;M University (TAMU), College Station, Texas; and Buell's Inc., Cibolo, Texas. Location had a significant effect on emergence, with both species having greater emergence percentages at Buell's Inc. than at TAMU. This effect is attributed mainly to watering systems and plug aeration. Priming significantly increased emergence of only E. purpurea grown at TAMU. Seedlings from seeds primed in 50 mM potassium salts for nine days at 15°C (59°F) had more than twice the emergence percentage (47%) of seedlings from nonprimed seeds (21 %). Priming did have a significant effect on the root development of both species. Echinacea purpurea seedlings from primed seeds had a 44 to 51% increase in total root area compared to nonprimed seeds. Coreopsis lanceolata seedlings from primed seeds had up to an 85% increase in root area compared to seedlings from nonprimed seeds. In plug systems, relatively developed root systems may result in positive growth response after transplanting.

Aging of tissues of the roots of nonfunctional human teeth (impacted canines)

In order to examine the aging of dentin and cementum, seventy-two impacted human canines, nonfunctional and not affected by external factors, such as attrition, abrasion, caries, etc., were surgically extracted. Ground sections were prepared and the areas of sclerotic dentin and cementum were measured with the aid of a planimeter and expressed as a percentage of the total root area. It was found that there is a significant increase in sclerotic dentin and apposition of cementum with an increase in age.

A return to large nonresilient straight arch wires

A return to large nonresilient straight arch wires

A serial cephalometric study of developmental growth patterns of Class I and Class II, Division 1 malocclusions before and after orthodontic treatment utilizing an original method of analysis: By William D. Berg, D.D.S., New York University, New York, N. Y.

A serial cephalometric study of developmental growth patterns of Class I and Class II, Division 1 malocclusions before and after orthodontic treatment utilizing an original method of analysis: By William D. Berg, D.D.S., New York University, New York, N. Y.