Root System Size Research Articles

Effects of Laminated Root Rot on Relationships Between Stem Growth and Root-System Size, Morphology, and Spatial Distribution in Douglas-fir

Abstract Root-system size (length, cross-sectional area, and volume) was measured in 30- to 40-year-old Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) in five stands. Mean root-system size varied widely among stands (length 2,485-5,316 cm; cross-sectional area 4,070-13,520 cm²; volume 72,760-251,020 cm³). Percentage of roots decayed by Phellinus weirii varied among stands and among root orders ranging 22-83 percent by length and 21-84 percent by volume. Root size distribution in P. weirii-infected trees was generally of the same magnitude and pattern as in healthy trees. Diameter at breast height (dbh) was highly correlated with total root-system size in all stands in all three root measures. Height was highly correlated with total root-system size in four stands. Diameter at breast height increment and dbh increment percent and height-dbh ratio were moderately correlated with root-system size in some stands and for some root measures. Height increment percent was poorly correlated with root-system size. Correlations of most stem variables with sizes or percent decay of roots stratified by root orders and by distance and depth zones were significantly stronger than correlations with total root-system size. Healthy and infected trees differed in the root orders and zones that were most strongly correlated with stem-growth variables. Diameter at breast height and height were mostly positively correlated with infected and healthy root sizes whereas increment variables were predominantly inversely correlated with infected root size. Stem radii measured vertically above junctions of infected roots with the stem base were smaller than those measured above junctions of healthy roots. Radial increments above infected roots producing adventitious branches were greater than those above other infected roots or above healthy roots. Forest Sci. 32:202-219.

A Nondestructive Method for Measuring Root System Surface Area

Abstract A method is described for obtaining nondestructive estimates of root system surface area. The technique is based on the assumption that the larger the root system, the more gel of a given viscosity will adhere to it. The correlation between gel adherence and 5 parameters of root system size (root length, root fresh weight, root dry weight, root volume, and root surface area) is established.

Relation between root system size and water inflow capacity of Abiesamabilis growing in a subalpine forest

The water inflow capacity of the root systems of several 15- to 18-year-old Pacific silver fir (Abiesamabilis (Dougl.) Forbes) trees was investigated under field conditions. Severance of as much as one-third of the roots had no effect on xylem pressure potential, leaf conductance, or transpiration throughout the day following this treatment. Severance of more than half of the root system caused a decline in xylem pressure potential and partial stomatal closure. Measurements from trees which had been completely severed from their roots indicated that stored water made only a small contribution to the supply of water to the foliage of these trees. It was concluded that a balance did not exist between the capacity for water inflow and the rate of foliar water loss, at least in periods without drought. One advantage of excess absorptive capacity may be the ability to obtain adequate amounts of water from relatively small portions of the rooting zone.

Soil-nitrogen accumulation in codulated and non-nodulated soybeans: A verification of the difference method by a 15N technique

The difference method of measuring nitrogen fixation in soybeans ( Glycine max (L.) Merr.) relies on the assumption that nodulated and nonnodulated plants utilize equal amounts of soil nitrogen (N). The validity of this assumption has been challenged by reports of differences in root system size for nodulated and nondulated and nondulated genotypes. This field study, using a 15N-tracer technique under conditions with reduced available soil N, was conducted to: (1) evaluate thee assumption that the nodulated and nonnodulated soybean genotypes utilize equal amounts of available soil N, (2) compare the root system mass in the nodulated and nonnodulated genotypes, and (3) determine the relationship between soil-N accumulation in the shoots and root dry-matter accumulation. In 1977 and 1978, one nonnodulated and six nodulated soybean genotypes were grown in replicated field plots labeled with 15N on an Aqualfic Normudult (silt loam) soil. Plantts were sampled at 49, 70, and 91 days after planting and at full maturity in 1977, and at 62 and 112 days after planting in 1978. Shoot and root dry-matter accumulation, seed yield (in 1977 only), total-N concentration, total-N accumulation, soil-derived N accumulation, and fixed-N accumulation were measured. Significant differences were present among genotypes both years for all variables except soil-derived N accumulation in the shoots. Shoot and root weights for the nonnodulated genotype could not be distinguished statistically from the nodulated genotype either year, although the seed yield for the nonoddulated was only 37% of the mean of yields for the nodulating genotype in 1977. Root dry weight was positively correlated with shoot dry weight ( r e = 0.90 for, 1977, r w = 0.86 for 1978), seed yield ( r w = 0.79 for 1977), shoot total-N accumulation ( r w = 0.82 for 1977, r w = 0.68for 1978), soil-derived N accumulation in the shoots ( r w = 0.71 for 1977), and accumulation of fixed-N in the shoots ( r w = 0.84 for 1977, r w = 0.85 for 1978). Results of this study support the assumption of equal utilization of soil-derived N by nodulated and nonnodulated soybean genotypes. The use of the difference method under conditions of low N fertility is appropriate for preliminary studies and in areas where 15N-tracer techniques are not available.

Phosphorus and Potassium Uptake of Field‐Grown Soybean Cultivars Predicted by a Simulation Model

AbstractMathematical models for calculating nutrient uptake by plants grown in soil have been successfully verified in pot experiments. However, few attempts have been made to verify the models for predicting nutrient uptake under field conditions. The Cushman mathematical model was tested for prediction of P and K uptake by soybeans (Glycine max L. Merr.) grown in the field; five cultivars were grown each year for 3 years. Experimental site varied with year. The soils used were Raub silt loam (fine silty, mixed, mesic Aquic Argiudolls) and Chalmers silt loam (fine silty, mixed, mesic Typic Haplaquolls). Observed P and K uptake was obtained from plant analysis. Root system size was obtained by taking soil core samples, washing the soil from the roots, and measuring root length and mean root radius. Root kinetic parameters for P and K influx were measured in solution culture experiments conducted in a controlled climate chamber. Soil nutrient supply parameters were measured in the laboratory on surface and subsoil samples. The model accurately predicted K uptake by the different cultivars grown in both soils and P uptake from the high‐P (52 µM in the soil solution) Chalmers soil. Prediction of P uptake from the low‐P (7.8 µM in the soil solution) Raub soil was 30 to 35% of the observed P uptake, even though predicted uptake by root hairs was included in the calculation. The difference may have been partly due to acidification of the rhizosphere soil by root exudate, which increased P concentration in soil solution and consequently increased P uptake.

Root development of container-reared, nursery-grown, and naturally regenerated pine seedlings

Root systems of 6- to 10-year-old red pine (Pinusresinosa Ait.) and jack pine (Pinusbanksiana Lamb.) trees reared in various containers were excavated from four different sites and studied. Nursery-grown and naturally regenerated trees of similar age and stem size growing on the same sites were used for comparison. Root cross-sectional area (RCSA) taken 5 cm from the stem, a measurement found to be highly correlated (r = 0.94) with root weight (In–In transformation), was used to describe root system size. The average RCSA's of jack pine reared in paper pots, book planters, and nonribbed styroblock-2 containers were smaller than those of naturally regenerated seedlings, but the differences were not statistically significant. Jack pine and red pine reared in Ontario tubes had significantly larger RCSA's than nursery-grown trees. There were some differences in radial distribution of horizontal roots, and the apportionment between horizontal and vertical root components differed between some of the seedling types.

Analysis of the Components of Area Growth of Bean Root Systems1

Root and leaf surface areas were measured on green bean (Phaseolus vulgaris L. cv. Ouray) plants, with light intensity (photosynthetic photon flux density, PPFD) as the major growth variable, to determine how various sizes of roots are related to water transport and growth rates of whole‐root systems. Plants were grown in aerated nutrient solution for 41 days in a greenhouse. Two light intensities were used: 425 and 320 μE m−2 sec−1 Leaf area:root area ratios, distribution of root sizes, and the fraction of the total root surface area of each root class were determined. All of these parameters remained stable for plants with leaf and root areas greater than 1,000 cm2 and they were unchanged by light intensity or growth rate. On the basis of previous data the mean root system hydraulic conductance (Lp) appeared to be keyed to plant size rather than age. The conductance was very low in small plants, increased about sixfold and peaked when the root systems reached approximately 1,000 cm2 surface area. For plants larger than 1,000 cm2, when the root size distributions were stabilized, conductance gradually declined, probably because of suberization or some other growth‐related factor. Plants grown at lower light intensity showed the same pattern of relationships between root system size, root size distribution, and hydraulic conductance except that the overall Lp was consistently lower for plants of similar sizes.

Effects of Infection by Phytophthora megasperma var. sojae on the Water Relations of Soybean

Soybeans infected by Phytophthora megasperma var. sojae had reduced transpiration rates, lower leaf water potentials, smaller leaves, and higher leaf temperatures than noninfected ones. Flow rates of water through infected soybean roots were one‐tenth those through healthy roots. Recovery from water stress by infected plants was slower than that observed among healthy plants. A 20‐fold greater whole root resistance to water flow was observed in excised roots of infected plants compared to controls. The influence of infection on root resistance greatly exceeded the influence of infection on the size of root systems.

I. Pathogenic variation in fungi and bacteria and mycorrhizal compatibility: Intraspecific variation in a mycorrhizal association

ABSTRACTLaboratory studies with combinations of the fly agaric, Amanita muscaria (L. ex Fries) Hooker and birch (Betula pendula (Roth.)) suggest that the genetical control of mycorrhizal formation has features in common with the legume/Rhizobium symbiosis. There are at least four factors that can be genetically controlled by either the host or the fungus: (a) mycorrhizal formation; (b) the extent of mycorrhizal development; (c) the pattern of mycorrhizal branching, and (d) the shape and size of the host root system.

Evaluation of the size of a plant's root system using its electrical capacitance

This paper extends an earlier one5. The relationship between electrical capacitance of a plant root system (C) and size (weight, volume, surface) of the root system (x) can be expressed by equation of the line $$C = a + bx$$ ifa equals size of parasitic capacitance of measurement, i.e. capacitance of soil, wires,etc. andb equals regression coefficient influenced by type of soil plant species, measuring frequency and voltage,etc.

Effects of Initial Establishment Practice on the Subsequent Productivity of Apple Stoolbeds

SummaryProduction of clonal M.9a stool shoots during a five-year period was adversely affected by establishing stoolbeds with plants below the size acceptable as liners for budding (length approximately 60 cm). Allowing plants to establish for two seasons before being cut down for stooling did not improve production. The size of the permanent root systems at the end of the experiment reflected differences in the initial size of planting material. Production from the more prolific clone MM.111 was much less affected by the size of plant used to establish the beds. It is suggested that for the less vigorous M.9a, severe annual pruning and late development of roots each year on the stool shoots prevented resources from accumulating to the benefit of the mother stool.

Methods of Bringing Tea into Bearing in Relation to Water Status During Dry Weather

SUMMARYDespite large visual differences in size and form of shoot and root systems of young clonal plants and of older seedlings, there was no convincing evidence that tea plants, brought into bearing by pegging, are necessarily more susceptible to water stress than similar plants that have been pruned, though the sap tension in pegged plants of one clone was often greater than in similar pruned plants. Further studies are needed to show whether this is the case in drier areas, but differences in responses to dry conditions by individual clones appear to be of greater significance.

The size of the root system of tetraploid red clover and its relation to the chemical composition of the herbage produced

AbstractThe size of the root system was measured by means of electrical capacitance in relation to the soil in field experiments with three varieties of tetraploid red clover over a period of 3 years. The root system was greatest in the first year, smaller in the second year and least in the third year. The plants that gave an above‐average yield in any cut always had above average‐sized root systems in the preceding period, but usually after cutting, the size of their root systems decreased, an effect which was accentuated by plants drying out. The plants that dried out during the experimental period always had below average‐sized root systems in preceding periods. It was found in four cuts that the herbage dry matter of the plants with larger roots contained a smaller proportion of nitrogenous materials and ash, and more fibre, but the yield of all measured nutrients and elements increased. The ash of the herbage DM of these plants contained more potassium, calcium and magnesium. The quantity of mineral materials absorbed per unit of size of root systems was higher in the plants with larger root systems.

Evaluation of Commercial Corn Hybrids for Tolerance to Corn Rootworms12

Commercial corn hybrids were tested to assess several field and greenhouse techniques of evaluating corn rootworm tolerance. Root-system size and secondary root ratings obtained in the field correlated well with percentage root lodging in the field. Rootsystem size ratings obtained in the greenhouse were highly correlated with those ratings obtained in the field. Greenhouse evaluations effective detected differences among hybrids for root-damage rating, a measure of antibiosis, but field evaluations did not. Hybrids did not differ significantly for the amount of yield reduction incurred from rootworm injury.

Effects of Fertilizer on Root Strength of Sherman Big Bluegrass (Poa ampla Merr.)1

AbstractPulling of plants by grazing animals animals has been a common problem on ‘Sherman%’ big bluegrass (Poa ampla Merr.) pastures in Colorado. Fertilizers were applied to individual plants in a greenhouse study to evaluate their influence on plant resistance to pullup. The fertilizer treatments were 56 kg/ha N, 56 kg/ha P, or 56 kg/ha of each element as an N+P combination. Fertilizer treatments were applied to vernalized and nonvernalized plants grown in two soils.Tensions required for pullup in the greenhouse were correlated with total root weight (r = .75**) and significantly increased with N fertilization. Plants fertilized with N produced more vegetative and reproductive shoots, tillers, foliage weight, and root system weight and length. Phosphorus fertilization produced a significant increase in vegetative and reproductive shoots, and a significant interaction between N and P was found for root system size and the amount of roots that were pulled from the soil with the plants.

Water‐Use Efficiency and Its Relation to Crop Canopy Area, Stomatal Regulation, and Root Distribution1

AbstractThe differences in water‐use efficiency between sorghum [Sorghum bicolor (L.) Moench] and soybean [Glycine max (L.) Merrill] were compared in terms of leaf area index (LAI), size of root system, canopy stomatal resistance (R̄c), net assimilation rate (NAR), and evapotranspiration (ET). The field water budget was measured by recording the rainfall, and irrigation water applied in relation to the ET as measured with two weighing lysimeters.The evapotranspiration rates of the two crops began to diverge about August 15. This was the period when the soybean canopy began to close and the soybean LAI increased to about 1.5 times that of sorghum. NAR for sorghum during stalk elongation and heading (Aug. 15) was nearly four times that of soybeans during that time.Divergence of the two evapotranspiration curves coincided with observed differences in canopy stomatal resistance. In August after a stress period, the R̄c for sorghum at 1 and 3 pm was nearly three times the R̄c for soybeans. The increase in R̄c for sorghum was concommitant with an air temperature increase of 3 C above the air temperature near soybeans.Sorghum had approximately twice the weight of roots per volume of soil as soybeans. Even though atmospheric demand for H2O was similar for the two crops, sorghum was able to close its stomata more than soybeans, and thus conserve soil water even with a larger root system and more water in the soil profile resulting from reduced evapotranspiration.Water‐use efficiency of sorghum (gm DM/kg H2O) was approximately three times that of soybeans on dry matter or grain yield bases.

Development of young pear trees with different rootstocks in relation to psylla infestation, pear decline, and leaf curl

Young Bartlett, Winter Nelis, and Hardy pear Pyrus communis L. trees with six different rootstocks were studied during 1961 through 1965. Non-topgrafted trees of each type of rootstock were included. Three treatments were used: (1) saran cages placed around entire trees (caged-control); (2) spray applications (exposed-control); and (3) psylla infestation with Psylla pyricola Foerster confined to branches of trees by means of organdy sleeve cages (psylla-infested). This study confirmed the decline tolerance of trees with Bartlett, Winter Nelis, or Pyrus calleryana Decne. seedling, or own-rooted Old Home P. communis rootstocks. Decline susceptibility was confirmed with trees with either P. serotina Rehd. or P. ussuriensis Maxim. rootstocks. Psylla-tight cages protected decline-susceptible trees—corroborating previous reports that the pear psylla is the pear decline vector. Differences in growth among trees with decline-tolerant stocks were small. Non-topgrafted rootstock trees attained greater size than their topgrafted counterparts; their vigor was correlated with the vigor and decline tolerance each type could impart as a root-stock for P. communis varieties. The size of root systems was correlated with trunk circumference and shoot growth. Tests also indicated that trees without graft unions may succumb to decline. Contrary to previous reports, these experiments showed that girdling from phloem sieve-tube necrosis is not always a prerequisite to the development of red foliage. Also, red foliage may indicate damage from psylla feeding alone or psylla feeding plus pear decline virus for non-topgrafred trees and decline-tolerant scion-stock combinations, as well as decline-susceptible ones. Leaf curl symptoms occurred in a large percentage of the exposed-control and psylla-infesred topgrafred trees, and in non-topgrafted Bartlett and Winter Nelis seedlings, and own-rooted Old Home. Differences in variety, source of scionwood, species or type of rootstock had little effect on incidence of curl. A few of the caged-control trees remained free of curl for more than a year after the cages were removed. This indicated that cages prevented or delayed its transmission by psylla. Psylla strains from New York and other sources, presumably free of pear decline virus, apparently induced curl in young pear trees, suggesting that the two diseases are separate entities. Evidently, complete exclusion of psylla would be required to control curl. The study revealed no outstanding differences among trees of one variety with the different decline-tolerant rootstocks. A mixture of the decline-tolerant rootstocks is recommended over any single rootstock for commercial plantings of the three varieties studied, however, because no one rootstock can be expected to be superior in all orchard situations.

The epidemiology of tomato mosaic

SUMMARYTomato plants (vars. Moneymaker and Minimonk) inoculated at the cotyledon stage with tomato mosaic virus (TMV) developed about half as much root as did healthy plants, by the time the first trusses were flowering. Although infected plants recovered to some extent, their roots remained 10–25% smaller. Infection at the flowering of the first truss reduced the size of root system by about one‐third after 6 weeks, but the plants then recovered. Infection at later stages of growth did not significantly affect root growth. There was no significant relation between the dry weight of the root system and the fresh weight of the top including fruit.Moneymaker and Potentate tomato plants, sown in November, March, June and September, showed similar seasonal changes in the volume of fruit produced weekly, whether or not the plants were healthy or infected with TMV. Infected plants always produced less than healthy ones, but the decrease varied with time of year and age of plant, being greatest in spring and in young plants; the decrease remained fairly steady in older plants. The initial period of acute decrease in volume of fruit production was greater when ovary swelling began early in the year than when it began later. Fewer fruits were produced by infected plants than by healthy ones, except during the winter in var. Moneymaker. During the winter and spring, mean fruit size was decreased by TMV, and was unaffected or increased during the summer and autumn, especially in older plants.