Root Boxes Research Articles

炭施用がカンキツの樹体生長およびVA菌根形成に及ぼす影響

Effects of several kinds of charcoal applied to soil on citrus growth and vesiculararbuscular mycorrhizal (VAM) development were investigated. Satsuma mandarin (Citrus unshiu Marc.) trees on trifoliate orange (Poncirus trifoliata Raf.) rootstocks were transplanted to root boxes using the soil mixed with charcoal derived from rice husk, citrus juice sediment or western spruce bark. The trees were inoculated with the spores of Glomus fasciculatum (Thaxter) Gerdemann and Trappe emend. Walker and Koske. Elongation of the roots in the charcoal treatments was more vigorous than that in the charcoal-free control. The fresh weigths of the root, shoot and the whole tree increased in response to charcoal application. The intensity of VAM infection in any charcoal treatment was higher than that in the control. In particular, the percentage of the infection in the rice husk charcoal plot was 41.5 and P concentration in the leaf exceeded that of the control.In a Citrus iyo orchard, the percentage of VAM infection was 52% in the rice husk charcoal plot, the highest among plots. The intensity in the Bahia grass (Paspalum notatum Flugge.) plot was next, followed by the third highest rate found in the abandoned plot which had not been cultivated in recent years. The lowest percentage of VAM infection was in a clean-culture plot. A microscopic observation also revealed that in a charcoal-treated plot there were many sites where VAM fungi infected the root.

Root growth ofRumexandPlantagospecies in compacted and waterlogged soils

SUMMARY The root patterns of Rumex palustris (Sm.), Rumex acetosa (L.) and Plantago major (L.) ssp. major, three species occurring in the river forelands, were studied in experimentally waterlogged or drained compacted soils and compared with specimens growing in drained loosely packed-soils as a control. A modified method for endoscopy in root boxes was developed. The species studied showed different patterns of root development as a result of soil waterlogging or compaction. R. palustris was the least sensitive to waterlogged soils, as shown by the formation of new, morphologically distinctive roots; R. acetosa was the most sensitive and P. major had an intermediate response. With respect to soil compaction P. major was the least affected species, followed by R. acetosa and R. palustris, respectively. The fractional root porosity of these species was studied by using a flow-through system to create hypoxia, a small soil-pore diameter or a combination of both. Hypoxia resulted in a higher root porosity. In both Rumex species small soil-pores inhibited this increase. Contrasting results were found for the porosity of Plantago roots. Results are discussed in relation to the distribution of these species in the field.

Cortical Sclerenchyma Development in Axile Roots of Cereal Crops.

A cereal root system consists of different axile roots that develop sequentially, i.e. (a) seminal root(s) (SR), mesocotylar roots (MR), nodal roots which originate from coleoptilar node (coleoptilar nodal root (CNR)), those from the 1st node (1 NR) and so on. The main objective of this study was to examine the histological features of basal parts of these roots with special reference to the occurrence of heterorhizy in cortical sclerenchyma development. Job's tears, Japanese barnyard millet, and pearl millet were planted in root boxes and grown in a growth chamber, with air temperature maintained at 25°C. The root systems were sampled at the 7th leaf expansion stage. In SRs and MRs, cortical sclerenchyma development was not observed among the three species. Some of the MRs in Japanese barnyard millet and pearl millet lacked the central metaxylem vessel. In all the species examined, it was CNR that first developed cortical sclerenchyma in the process of root system formation. In half of the CNRs observed for pearl millet, however, cortical sclerenchyma development was absent, suggesting that its development is quite plastic. Subsequently, its development was also recognized in 1 NRs and 2 NRs. Histological characteristics of this tissue were less distinct in the CNRs, while they were most distinct in the 2 NR. This result suggests that cortical sclerenchyma development in the axile roots of the species proceeded with the progress of ontogeny.

Acropetal Lignification in Protective Tissues of Cereal Nodal Root Axes as Affected by Different Soil Moisture Conditions.

This study aimed to examine the effects of different soil moisture conditions (waterlogging, moderate, drought) on acropetal lignification in protective tissues (hypodermis, cortical sclerenchyma, endodermis) in the 1st nodal roots of Job's tears (waterlogging tolerant, drought susceptible), Japanese barnyard millet (walerlogging and drought tolerant), and pearl millet (drought tolerant, waterlogging susceptible). They were grown in root boxes for 41 days. For Job's tears, lignification in the hypodermis and the cortical sclerenchyma tended to be promoted as the soil moisture conditions became drier, and the reduction in shoot dry weight by drought was not very serious. For Japanese barnyard millet, lignification in the hypodermis tended to be promoted by wetter conditions, while in the cortical sclerenchyma, drought also tended to promote lignification. The shoot dry weight was only slightly reduced under both coditions. Conversely, in pearl millet, the waterlogging drastically inhibited not only the lignification in the hypodermis but even the differentiation of the cortical sclerenchyma itself. Accordingly, shoot as well as root system growth was severely restricted under the same conditions. In contrast, for pearl millet grown under drought, the lignification was promoted in all the three protective tissues, and the shoot growth reduction was relatively slight. These results strongly suggest that the acropetal lignification in these tissues, especially that of the cortical sclerenchyma, may be closely related to waterlogging and drought tolerances of the crops.

Interspecific Differences of the Root System Structures of Four Cereal Species as Affected by Soil Compaction

Comparison of the root system structures of four cereal species as affected by soil compaction was conducted morphometrically. Plants were grown under two different soil bulk densities of 1.33g/cm3 (control)and 1.50g/cm3 (compact) for two weeks in the root box, and measurements were made on the number, length and diameter of all the roots from every component of the root system. Promoted or less restricted growth was recognized in the mean length and number of higher order laterals in every species under compact treatments. The increased occurrence of L-type lateral roots in the compact treatment contributed to the promoted growth of higher order laterals. Compared to upland rice and Job's tears, sorghum and maize showed higher restriction in both shoot and root growth. As for the occurrence ratio of L-type laterals in the compact treatment, the former two species had 1.5 to 3 times that of the latter two species. Regardless of root diameter, the species with longer root length showed higher restriction of total root length in both 1st and 2nd order laterals. It was suggested that the ability to produce L-type laterals and extension rate of each order lateral roots were closely related to root growth responses under mechanically impeded soil conditions.

In situ visualization of the biocontrol rhizobacterium Enterobacter cloacae with bioluminescence

Plasmid pUCD607 was mobilized into the biocontrol agent Enterobacter cloacae strain E6 by conjugation and the resultant strain, E6(pUCD607), was bioluminescent. Biocontrol of Pythium ultimum by E6(pUCD607) was similar to that of the parent strain, E6. The location of E6(pUCD607) in the soil and in the rhizosphere of lettuce was readily determined by pressing agar medium against plant roots in a root box, allowing the bacteria to grow overnight on the medium, and detecting the presence of bioluminescence by autophotography. There was a positive, linear correlation between population sizes determined by dilution plating and the quantity of light emitted due to bioluminescence. However, both the intercept and slope of this line varied among experiments possibly due to the differing physiological states of cells recovered from soils. The amount of light emitted by the bioluminescent strain E6(pUCD607) was not quantitative. This technique is useful for qualitative determinations of populations and for photographically locating bacteria.

Development of a device for estimating penetration resistance of the soil in the root box.

A device to measure soil penetration resistance in a root box (24cm×2cm×40cm) was developed, and its validity was examined for the revised root box method. The device was constructed with the metal probe (2.3 mm diameter and 50 cm length piano wire), strain gauge, linear displacement transducer, reversible motor and X-Y recorder. The main characteristic of this device is to push the needle type probe into the soil continuously about 40 cm downward at a constant rate to measure the penetration resistance easily and quickly as a function of soil depth.Edge effect was examined using probes with different diameters ranging from 0.95 to 2.3 mm. Edge effect was found to be negligible for any measured soil resistance value. Comparing spot resistance and continuous resistance, the skin friction was almost statistically constant (meaning it did not accumulate) under around 10 cm soil layer. The trend of the variation of both resistances as a function of soil depth was similar especially in the pattern of their peaks. Thus, the measured values were considered to be valid and therefore practical to use in determining penetration resistance as a function of soil depth, as a relative value.Age hardening process of the soil in the root box as a function of soil depth was examined under submerged condition. Penetration resistance tended to get bigger as soil depth increased.

Mutual relationship between patterns of soil penetration resistance and root radial expansion growth of upland rice.

The root boxes (24cm×2cm×40cm) filled with soil at two different soil bulk densities of 1.33 g/cm3 (control) and 1.50 g/cm3 (compact), were prepared for studying mutual relationship between the variation of penetration resistance as a function of soil depth and radial expansion growth of root axis. Upland rice was grown under both soil conditions for two weeks, and the root systems were sampled by pinboard method. Penetration resistance determined by a developed penetrometer showed several peaks of resistance throughout the entire depth of the root boxes caused by the presence of soil boundary layers resulting from the procedure of soil filling up. There were also found variations of root diameter of seminal axis and lst order lateral roots emerged from the seminal axis as a function of soil depth. In the compact plot, patterns of the penetration resistance corresponded well with those of root diameter. However, in the control, the correspondence of both patterns was not as clear as in the compact. These results indicated that patterns of soil mechanical impedance along the entire depth of the root box could be recorded in root axes as the history of radial expansion growth when root tips were exposed to higher mechanical impedance. The result obtained in this experiment suggested the necessity of considering the patterns of soil mechanical impedance in the growth media for the study of root-soil interaction.

Urban Nature Conservation in Britain

This study was conducted to identify chemicals in root exudates and their effect on Rhizoctonia solani in potato cropping systems. Root exudates were collected from the fields with 5 years of continuous potato cropping in comparison with rotational cropping of potato and other crops, using in-house made root boxes at the seedling and squaring stages. Chemicals in the root exudates were identified using the GC-MS method. The results showed that glucide concentration was the highest in the root exudates, followed by organic acids. Compared with the rotational cropping, the continuous cropping significantly decreased the glucide content and increased the content of organic acids in the root exudates. The contents of almitic acid in root exudates under continuous cropping was 0.94% at seedling stage and 1.4% at squaring stage, the dibutyl phthalate was 0.15%, whereas under rotational cropping, those values were decreased to 0.15%, 0.2%, and being negligible, respectively. The root exudates promoted the growth of R. solani, especially under continuous potato cropping. The simulation test showed that the palmitic acid and dibutyl phthalate in root exudates could promote the growth of R. solani.

ウンシュウミカンの幼樹の生長と養分吸収の温度条件

One-year-old satsuma trees (cv. Okitsu Wase) on trifoliate orange were grown in a growth chamber where day and night temperature were kept constant at 15, 20, 25 and 30°C for 7 or 9 months. The effects of temperature on vegetative growth and nutrient absorption were investigated.1. Potted trees were transferred into the growth chamber in April and grown until late October of 1979. Budbreak occurred considerably earlier at higher temperatures. Trees at 15 and 20°C sprouted flushes only in spring and these shoots produced some flower buds during September through October. Trees at 25°C flushed spring, summer and autumn shoots, and those at 30°C had an additional cycle of flush. Total shoot length of the trees at 30°C was the greatest. Fresh and dry matter increased in both tops and roots with rising temperatures, but at 30°C they slightly decreased. The leaves of trees at 20°C contained the highest amount of nitrogen and phosphorus. Calcium and potassium contents increased as temperature rose. Other mineral contents examined were lowest at 15°C. Total amount of mineral elements absorbed by the trees increased with rising temperature from 15 to 25°C, but slightly decreased at 30°C2. Root growth was observed using root boxes (30×20×25cm) for 9 months from April through December, 1982. High temperature stimulated root growth. At 30°C trees grew rapidly and had five growth cycles for shoots and three for roots. In contrast, root growth of trees at 15°C was severely restricted. In all cases, root growth always followed shoot growth. The rate of root growth increased just after spring and summer flushes, and had two clear peaks, excepting in trees at 15°C. Root growth showed the same pattern at all temperatures above 20°C. At 15°C, however, roots grew slowly but continuously without any peaks. The higher the temperature. the greater the total root length obtained by the end of the experiment.

Visualisation of oxidizing power of rice roots and of possible participation of bacteria in iron deposition

AbstractThe oxidizing power of rice roots was observed in narrow transparent root boxes containing different media. Plants precultivated in nutrient solution were embedded in semisolid agar medium to observe oxidation of ferrous iron cations and leuco methylene blue as well as solubilization of ferrous sulfide. In the presence of ferrous sulfate reddish brown coloration due to formation of ferric oxide/hydroxide was observed around the roots and on the root surface during one day of incubation. When agar medium blackened by ferrous sulfide was used, the root zone became transparent. Within a few hours leuco methylene blue was oxidized to methylene blue on and near the roots. Furthermore, seedlings were grown in agar medium containing ferrous sulfide inoculated with soil filtrate. Besides diffuse ferric iron precipitation, iron was also deposited on spherically shaped structures in the rhizosphere and near the agar surface as well as in slimy layers appearing on the root surface. The spherical structures and slimy layers were obviously bacterial colonies extending with time. As the roots grew old, parts of them turned black. In the rhizosphere, black spots occurred resembling colonies of sulfate‐reducing bacteria. Rice was also grown in sand supplemented with nutrients and iron sulfide. While root growth was straight in agar, it was twisted in the sand medium. Again, heavy ferric iron deposition occurred on the root surface. On older root parts the lateral roots became blackish. The results suggest participation of bacteria in ferric iron deposition in the rhizosphere of rice.

Variation in Seed and Seedling Size in Anthoxanthum odoratum

Success at the juvenile stage of the life cycle may have important consequences for the size-hierarchies and distribution patterns of adult plants. This study was designed to evaluate the factors contributing to variation in seed and seedling size in Anthoxanthum ordoratum. In experiments in the greenhouse and within the natural habitat of this species, significant differences in seed weight were found among inflorescences and maternal half-sib families, and marginal differences were found among populations. Larger seeds had a higher probability of germinating and individuals from them had a longer leaf length as juveniles. Covariate analysis showed that differences among populations in leaf length were caused by population differences in seed weight. Root growth was studied using plexiglass root boxes. Individuals from larger seeds tended to produce longer roots, and there were no differences among populations, maternal families, or inflorescences for root length.

A revised experimental system of root-soil interaction for laboratory work.

A set of experimental system for the study on the root system-soil interaction for laboratory work was presented. This system consisted of the following apparatuses and associating techniques for operation; (1) a handy-type root box covered with a mirror sheet, (2) a pinboard which enabled sampling of the root system in the root box soil as it stood in the soil, (3) a piece of holed polyethylene sheet for handling during the sampling of the root system and preserving the root system without impairment and disarrangement after sampling, (4) a transmitted light box for taking photograph of the root system. Techniques associating with those apparatuses consisted of the soil filling up into the root box, supplying water to the root box, washing out the root system from soil, and staining the sampled root system.Distribution patterns of soil porosity and moisture, and daily changes of soil temperature in the root box soil, were determined. Our soil filling-up technique gave high reproducibility as well as uniform porosity distribution in the root box soil with small difference among the root boxes. No significant differences were found in the soil moisture content at a given depth of horizontal soil layer. When the root box was put into the trench, the soil temperature in the root box was closer to that of a natural soil profile than when it was placed on the ground. Upland rice and maize were grown in the root box placed in the trench. Root systems sampled showed considerably uniform profiles among triplicated plants for both species. These results demonstrate the significance of preparation and control techniques of soil environments for the study on root system-soil interaction.

A Plastic-faced Root Box Culture for the Distribution Research of Nodule Formation and Nitrogen Fixing Activity on Leguminous Root Systems

A Plastic-faced Root Box Culture for the Distribution Research of Nodule Formation and Nitrogen Fixing Activity on Leguminous Root Systems

Root Development of Sericea Lespedeza and Alfalfa in Acid Soils1

AbstractA more thorough understanding of sericea lespedeza [Lespedeza cuneata (Dum.) G. Don] root system development is needed to improve management of seedling stands during establishment, especially in acid subsoils, which often limit root development of legumes. A greenhouse experiment was conducted using glass‐front root boxes to quantify seedling root system development of five lines of sericea lespedeza and ‘Apollo’ alfalfa (Medicago sativa L.) in acid (high AI and Mn) and limed soil layers underlying limed surface soil. The root boxes were partitioned into six 12.5 cm by 12.5 cm by 80 cm deep sections and each section was packed with Bradson clay loam (clayey, oxidic mesic Typic Hapludults) topsoil. Root growth rate (GR) and rooting intensity (cm cm−2 viewing surface) were monitored by tracing daily root growth on mylar sheets covering the glass front of the boxes. Measurements of root GR in limed subsurface soil indicated that alfalfa taproots elongated at twice the rate of the sericea entries evaluated. Alfalfa root GR was reduced by 69% in unamended soil, whereas root GR was not reduced in three sericea lines in the unamended treatment. Rooting intensity of 0.79 in alfalfa was twice that of sericea; however, in acid soil, abnormally branched and swollen secondary roots represented a large portion of the alfalfa root system. In addition, secondary taproot growth (thickening) in alfalfa was reduced 30% in both the surface and subsurface soil of the unlimed treatment. Root/shoot ratios based on root length in limed subsoil indicated that sericea produces more root growth per unit shoot than alfalfa.

Field Resistance in Three Native Monocotyledon Species That Colonize Indigenous Sclerophyll Forest After Invasion by Phytophthora cinnamomi

Lepidosperma laterale (Cyperaceae), Gahnia radula (Cyperaceae) and Poa sieberana (Poaceae) colonize bare ground of dry sclerophyll forest after disease due to P. cinnamomi. To determine their resistance, plants grown in divided root boxes were inoculated with 150-200 zoospores of the pathogen. Infected roots ceased growth. In the small necrotic lesions produced, the pathogen remained viable and capable of providing a source of inoculum for disease extension. Fungal growth was usually limited to the lesion but in some cases a few hyphae were observed in adjacent tissue. Away from the lesion there was a rapid reduction of fungal material and of the associated cellular disintegration. Rates of root production and root growth were not stimulated by infection but uninfected lateral roots replaced the root tip in some plants; in others, a new root tip emerged from the necrotic zone, enabling the plant to outgrow the fungal attack.

Relationship between plant type and root growth in rice

Abstract The relationship between plant type and root growth was examined using the root box technique. Correlation studies on 1,081 varieties or lines indicated that the deep root system is correlated with taU plant stature and low tiller number; it is not closely correlated with Iong growth duration. Subsequent studies on two isogenic lines of early Peta with different plant heights, however, indicated that plant height is not related to rooting depth. The same conclusion was reached from a comparison of three sorghum varieties with different plant heights. The shortest of the three varieties had the deepest root system. Examination of tillering habit and root growth of individual shoots (tiller or main culm) c1early showed that earIy tillers have more and longer roots than do Iate tillers regardless of the tiller order and the position of the node from which they emerge. Thus, a high tiUering plant tends to have a short root system. The advantages and disadvantages of low- or high-tillering varieties i...

Assessment of Acetylene Reduction by Sainfoin and Alfalfa over Three Growing Seasons1

Sainfoin (Onobrychis viciifolia Scop.) has many positive characteristics as a forage legume, but frequently exhibits poor stand persistence. Insufficient nitrogen (N2) fixation has been suspected contributing to the stand persistence problem in sainfoin. Nitrogen fixation (acetylene reduction) rates of sainfoin have been reported for seedling plants, however, there is no information on fixation rates for established stands.A root box technique which allowed for the measurement of acetylene reduction on intact perennial plants for several growing seasons was used. Acetylene reduction of sainfoln and alfalfa (Medicago sativa L.) grown in soils collected from six existing sainfoin fields was measured at various stages of plant growth over three growing seasons. Sainfoin acetylene reduction rates were 36 to 75 % greater than alfalfa with the difference increasing with plant age.Percent non‐structural carbohydrates (NSC) were 10 % higher alfalfa taproots compared to sainfoin after the third growing season. Total NSC of sainfoin and alfalfa taproots was 1.8 and 6.9 g, respectively. Visual observation indicated that root and crown diseases resulted in significant mortality of sainfoin.Results indicated that acetylene reduction of sainfoin was superior to alfalfa while a consistent trend favoring a particular soil was not found. Carbohydrate storage and disease susceptibility may contribute more to the stand persistence problem of sainfoin than poor N2 fixation.

Studies of Nitrogen Fertilizer Placement in Soybean by Use of Root Boxes

Studies of Nitrogen Fertilizer Placement in Soybean by Use of Root Boxes

SPROUTING AND DEVELOPMENT OF YELLOW NUT SEDGE TUBERS

Tubers of yellow nut sedge (Cyperus esculentus L.) were collected from four farm fields representing three soil types in southern Ontario in November of 1974 or 1975. These fields contained from 760 to 8,484 tubers/m2 in the top 40 cm of soil. Tubers extracted from these soils failed to sprout following 6 wk of storage under dry conditions, but sprouting approached 100% if previously stored under cool, moist conditions. Cool temperatures during dry storage for 90 wk reduced subsequent sprouting. Tubers sprouted as well in the greenhouse as in petri plates in a germination chamber. Root growth averaged 2 cm/day in glass-lined root boxes and tuber initiation commenced 90 days after planting. Tuber production was greatest under a short day length of 12 h or less, while shoot and root growth was stimulated by a long photoperiod.