Defoliated Plots Research Articles

Effects of Soybean Plant Population on Yield Loss From Defoliation.

Plant densities in Mid-South U.S. soybean, Glycine max (L.) Merr., fields can vary greatly due to a wide range of factors, although soybean yields are generally insensitive to variations in density. Currently, it is unknown if yield loss from insect-related defoliation varies across different soybean stand densities. Soybean was planted in Starkville and Stoneville, MS, in 2016 and 2017 at five seeding rates ranging from 123,500 to 420,070 seed/ha in 74,130 seed/ha increments. Each seeding rate contained a nondefoliated plot and a plot that was defoliated 67% at the R1 growth stage. Defoliated plants had a greater leaf expansion rate from R1 to R3 than nondefoliated plants. Defoliation reduced yield where plant densities were <192,800 plants/ha, but greater densities were not affected. Reduced yield in defoliated plots when compared with nondefoliated plots at equivalent R3 leaf area index values indicated that some resources were used to replace the removed leaf area instead of seed production. These results suggest that fields with substandard plant densities might benefit from a reduced treatment threshold for defoliating pests.

Low canopy cover in a sown Digitaria eriantha Steud. pasture improves establishment of Trifolium subterraneum L.

ABSTRACTIn the summer-dominant rainfall zone of inland northern New South Wales and southern Queensland, tropical grass-temperate legume mixed pastures can provide forage for grazing livestock for most of the year; however, the effect of canopy cover and its interaction with ground cover for regeneration of Trifolium subterraneum (subterranean clover) are not known. An experiment was conducted using established Digitaria eriantha with two levels of canopy cover (defoliated to 0.1 m and undefoliated) and four levels of ground cover (ranging from bare to 75%). Plots were oversown with subterranean clover seed in May–June, and legume establishment and spring herbage production were assessed. Low rainfall throughout the experiment resulted in poor clover establishment and production but seedling densities were significantly higher in the defoliated treatments (14 cf. 6 seedlings/m2). Herbage production was also significantly higher in the defoliated plots (530 cf. 302 kg DM/ha). There was no effect of ground cover. These findings indicate that management strategies that remove excess forage and reduce canopy cover of tropical grass pastures in late summer will maximise regeneration of subterranean clover in autumn.

Slowed Biogeochemical Cycling in Sub-arctic Birch Forest Linked to Reduced Mycorrhizal Growth and Community Change after a Defoliation Event

Sub-arctic birch forests (Betula pubescens Ehrh. ssp. czerepanovii) periodically suffer large-scale defoliation events caused by the caterpillars of the geometrid moths Epirrita autumnata and Operophtera brumata. Despite their obvious influence on ecosystem primary productivity, little is known about how the associated reduction in belowground C allocation affects soil processes. We quantified the soil response following a natural defoliation event in sub-arctic Sweden by measuring soil respiration, nitrogen availability and ectomycorrhizal fungi (EMF) hyphal production and root tip community composition. There was a reduction in soil respiration and an accumulation of soil inorganic N in defoliated plots, symptomatic of a slowdown of soil processes. This coincided with a reduction of EMF hyphal production and a shift in the EMF community to lower autotrophic C-demanding lineages (for example, /russula-lactarius). We show that microbial and nutrient cycling processes shift to a slower, less C-demanding state in response to canopy defoliation. We speculate that, amongst other factors, a reduction in the potential of EMF biomass to immobilise excess mineral nitrogen resulted in its build-up in the soil. These defoliation events are becoming more geographically widespread with climate warming, and could result in a fundamental shift in sub-arctic ecosystem processes and properties. EMF fungi may be important in mediating the response of soil cycles to defoliation and their role merits further investigation.

Effect of forest structure and health on the relative surface temperature captured by airborne thermal imagery – Case study in Norway Spruce-dominated stands in Southern Finland

ABSTRACTThe effect of forest structure and health on the relative surface temperature captured by airborne thermal imagery was investigated in Norway Spruce-dominated stands in Southern Finland. Airborne thermal imagery, airborne scanning light detection and ranging (LiDAR) data and 92 field-measured sample plots were acquired at the area of interest. The surface temperature correlated most negatively with the logarithm of stem volume, Lorey’s height and the logarithm of basal area at a resolution of 254 m2 (9 m radius). LiDAR-derived metrics: the standard deviations of the canopy heights, canopy height (upper percentiles and maximum height) and canopy cover percentage were most strongly negatively correlated with the surface temperature. Although forest structure has an effect on the detected surface temperature, higher temperatures were detected in severely defoliated canopies and the difference was statistically significant. We also found that the surface temperature differences between the segmented canopy and the entire plot were greater in the defoliated plots, indicating that thermal images may also provide some additional information for classifying forests health status. Based on our results, the effects of forest structure on the surface temperature captured by airborne thermal imagery should be taken into account when developing forest health mapping applications using thermal imagery.

Defoliation and Soil Compaction Jointly Drive Large-Herbivore Grazing Effects on Plants and Soil Arthropods on Clay Soil

In addition to the well-studied impacts of defecation and defoliation, large herbivores also affect plant and arthropod communities through trampling, and the associated soil compaction. Soil compaction can be expected to be particularly important on wet, fine-textured soils. Therefore, we established a full factorial experiment of defoliation (monthly mowing) and soil compaction (using a rammer, annually) on a clay-rich salt marsh at the Dutch coast, aiming to disentangle the importance of these two factors. Additionally, we compared the effects on soil physical properties, plants, and arthropods to those at a nearby cattle-grazed marsh under dry and under waterlogged conditions. Soil physical conditions of the compacted plots were similar to the conditions at cattle-grazed plots, showing decreased soil aeration and increased waterlogging. Soil salinity was doubled by defoliation and quadrupled by combined defoliation and compaction. Cover of the dominant tall grass Elytrigia atherica was decreased by 80% in the defoliated plots, but cover of halophytes only increased under combined defoliation and compaction. Effects on soil micro-arthropods were most severe under waterlogging, showing a fourfold decrease in abundance and a smaller mean body size under compaction. Although the combined treatment of defoliation and trampling indeed proved most similar to the grazed marsh, large discrepancies remained for both plant and soil fauna communities, presumably because of colonization time lags. We conclude that soil compaction and defoliation differently affect plant and arthropod communities in grazed ecosystems, and that the magnitude of their effects depends on herbivore density, productivity, and soil physical properties.

Influence of defoliation on CO 2 efflux from soil and microbial activity in a Mediterranean grassland

Defoliation of grasses affects carbon (C) input from plants into the rhizosphere and so may affect C turnover in soil. We examined the effect of grassland's defoliation on root-derived CO 2 efflux and microbial activity in Mediterranean Phaeozem. In situ partitioning of total CO 2 efflux into root-derived and microbial-derived CO 2 fluxes was performed by mesh-exclusion technique. Microbial basal respiration, N mineralization and the activity of enzymes involved in the cycling of C, N, P and S (also used to calculate microbial functional diversity) were measured in soils of defoliated and control plots. Cumulative CO 2 efflux in defoliated plots was 18% lower in 2006 and equal to control plots in 2007. The contribution of microbial CO 2 to total CO 2 efflux from soil ranged from 71% to 86% without significant differences between defoliated and non-defoliated plots. The lack of correlation between root-derived CO 2 and soil temperature after defoliation indicates that photoassimilate supply is the major determinant for root-derived CO 2. Microbial-derived CO 2 efflux was 20% lower in defoliated plots after accounting for temperature and humidity differences between the two treatments. Defoliation suppressed the activity of enzymes involved in the cycling of C, S and P and decreased basal respiration rates of soil microorganisms by 19%. In turn, defoliation stimulated activity of enzymes involved in the cycling of N, as indicated by the increase of potential nitrification rates and of leucine-aminopeptidase activity. Stimulation of N mineralization promotes a fast regeneration of defoliated plants. We confirm the presence of strong links between plant and microbial activity in a grassland community, as well as close coupling of aboveground photosynthetic activity with root-derived CO 2.

Resilience of mycorrhizal fungi on defoliated and fertilized hybrid poplars

We examined the effects of fertilization and gypsy moth defoliation of hybrid poplar (Populus ×canadensis Moench 'Eugenei') on ectomycorrhizal (ECM) and arbuscular mycorrhizal (AM) fungal colonization, ECM richness, and ECM composition in the summers of 1997 and 1998. The factorial experiment included two levels of defoliation (defoliated and control) and fertilization (100 kg N·ha–1and control). Gypsy moth (Lymantria dispar L.) populations were manipulated to obtain defoliation in the summer of 1996, 1997, and 1998; fertilization subplots were fertilized with NH4NO3(100 kg N·ha–1) in the spring of these years. There were no significant effects of defoliation on ECM or AM colonization in either year; there was a significant (p ≤ 0.05) decline in AM colonization in fertilized plots in 1997 and a significant interaction between defoliation and fertilization effects on ECM colonization in 1997. In the nondefoliated plots, ECM fungal colonization increased, whereas AM colonization decreased because of fertilization. In the defoliated plots, neither ECM nor AM colonization was affected by fertilization. ECM community composition and richness were unchanged by any treatment. The small and transient effects of defoliation and fertilization on poplar AMs and ECMs demonstrate the tolerance of these early-successional trees to defoliation and their ability to rapidly use high levels of available nitrogen.Key words: Populus, nitrogen, ectomycorrhizas, arbuscular mycorrhizas, ectomycorrhizas, Lymantria dispar (gypsy moth), defoliation.

Spruce budworm defoliation and growth loss in young balsam fir: relationships between volume growth and foliage weight in spaced and unspaced, defoliated and protected stands

Foliage weight (FW) and tree volume, volume increment (VI), and specific volume increment (SVI) were examined throughout a spruce budworm ( Choristoneura fumiferana (Clem.)) outbreak cycle from 1976 to 1984, for young balsam fir ( Abies balsamea (L.) Mill.). Treatments were spaced and unspaced, defoliated and protected (annual insecticide spraying to prevent defoliation). Six years into the outbreak, FW in defoliated plots reached its minimum levels, representing a reduction of 83.3 and 84.3% for spaced and unspaced stands, respectively, compared with the protected stand. For surviving trees, FW recovery was rapid and substantial (threefold to fivefold over 3 years), due to the release of suppressed buds. Still, at the end of the outbreak, FW was reduced by 37.5 and 68.5% for spaced and unspaced stands, respectively. VI was reduced by 92.5 and 91.1% and SVI by 92.0 and 89.3% for spaced and unspaced stands, respectively, compared with the protected stand. This severe budworm outbreak reduced growth rates by about the same level, regardless of initial differences in growth rates and density. By the end of the outbreak, volume was reduced by 32.6 and 54.1 m 3/ha for spaced and unspaced stands, respectively, or a decrease of 51.7 and 35.7% compared with the protected stand. Relationships between VI and FW were, in general, linear for spaced trees and a mixture of linear and non-linear for unspaced trees. On an individual-tree basis, VI: FW relationships were strong at the beginning and end of the spruce budworm outbreak, but weaker in the middle. Combining all years, on a per hectare basis, the relationships between VI and FW were strong ( r 2=0.78 for spaced and 0.80 for unspaced stands), and still held despite defoliation.

Susceptibility of northern British Columbia forests to spruce budworm defoliation

Stand susceptibility to defoliation by spruce budworm, Choristoneura fumiferana (Clem.), was examined in the Fort Nelson area of the Prince George Forest Region of British Columbia. In a retrospective study, defoliation maps of the study area were overlaid onto British Columbia Ministry of Forests cover type maps using a geographic information system. Analysis of the combined data identified forest characteristics associated with increased susceptibility to defoliation by spruce budworm. These were stands where the leading species was white spruce ( Picea glauca (Moench) Voss), or where spruce was associated with aspen ( Populus tremuloides Michx. and P. balsamifera L.) in mixed stands. Susceptibility to defoliation also was related to site quality, level of crown closure and stand age. Spruce stands on medium quality sites (site index 15 to 25 m, at reference breast height age 50 years) were more susceptible than stands on both poor- and high-quality sites. When spruce was mixed with aspen, stands on higher quality sites were more susceptible to budworm attack than poor sites. Open stands, where crown closure was <50%, were more susceptible to attack by spruce budworm than closed canopy stands. Older stands (120–199 years) were more susceptible to budworm attack than younger stands (40–110 years). In defoliated plots monitored for 6 years, tree mortality and top-kill reached a maximum of 30.4 and 47.2%, respectively. The losses varied with level of defoliation and were reduced by applications of the biological pesticide Bacillus thuringiensis.

Defoliation of a Northern Wheatgrass Community: Above- and Belowground Phytomass Productivity

A defoliation study was conducted on a fair condition, clayey range site that is potentially dominated by northern wheatgrass (Agropyron dasystachyum (Hook.) Scribn.) in south-central Saskatchewan. Vegetation was subjected to a factorial experiment with an initial defoliation in early-May, June, July, or August and repeated at 2- or 6-week intervals until mid-September in the same plots for 3 years. An undefoliated control was also included. Herbage removed, residual live, dead, total and root phytomass were measured. Defoliation reduced all yield components, with the exception of herbage removed. Residual live grass was reduced 37, 57, and 46%, respectively, in first second, and third years; the sedge and forb components of live residual phytomass generally were not affected by defoliation. Compared to control, dead phytomass was reduced 77% in the first year, 67% in the second, and 52% in the third year across treatments. Total herbage yield across defoliation treatments ranged from 68 to 93% of control Total live phytomass (herbage removed + residual live phytomass) in defoliated plots equaled control Herbage removal was greatest when initially defoliated in early July and thereafter at 2-week intervals. When defoliated at 6-week intervals residual live and dead phytomass were generally greater than when herbage was removed biweekly. Yields were higher when the first defoliation was delayed and repeated at 6-week intervals. Generally, root phytomass was not different among defoliation treatments, but total belowground phytomass was reduced 30% in the 0-30-cm depth after 3 year of defoliation. This northern mixed prairie ecosystem is sensitive to herbage removal. Maximum forage yield can be obtained if grazing is deferred until after peak growth in July.

Rooting dynamics of Medicago sativa seedlings growing in association with Bothriochloa caucasica.

Medicago sativa was seeded into an established sward of Bothriochloa caucasica. Two frequencies of sward defoliation were compared to a nondefoliated control. Although 84 to 92% of the root mass at 0-20 cm belonged to B. caucasica during the spring and summer samplings, defoliation generally reduced the root mass of B. caucasica. During the summer, aboverground mass of B. caucasica ranged from 735 to 1220 g m-2 and 295 to 410 g m-2 for control and defoliation treatments, respectively. Defoliation apparently reduced the competitive effects of B. caucasica on M. sativa, as taproot and lateral root mass of M. sativa was much higher in defoliated than in control plots by the end of the growing season. Predawn xylem potential of M. sativa was 0.4 to 0.8 MPa more negative in control than in defoliated plots from mid-summer to fall. Thus, we suggest that the transpirational demand of undefoliated B. caucasica reduced soil moisture available to M. sativa, thereby reducing its growth and survival during late summer and fall, compared to defoliated treatments.

Responses to defoliation of species-rich and monospecific tropical plant communities.

Floristically rich and monospecific tropical plant communities both responded to partial defoliation with increases in rates of production of new leaf area. Even after 50% of the leaf area had been removed three times, the leaf area increments were still higher in defoliated plots than in controls. Mean leaf area increment after defoliation, on a leaf area per unit ground area basis, was 905 cm2 m-2 d-1 in diverse successional vegetation and 536 cm2 m-2 d-1 in a cassava monoculture. Although defoliation stimulated leaf area development, on a per unit ground area basis, in both the cassava monoculture and the successional vegetation, the effect was more pronounced in the successional vegetation. On a per unit leaf area basis, leaf area increments following defoliation in both the diverse successional vegetation and the monoculture were approximately five times those of controls. The diverse plant community continued to respond vigorously after repeated defoliation, while the amount of stimulation of leaf are development in the monoculture declined. Because of their ability to respond even after repeated defoliation, diverse communities may in the long term be more homeostatic with respect to leaf area than are monocultures. The enhanced responsiveness of the species-rich community was due to changes in plant species abundance and very rapid leaf area development by some species.

Persistence of a Lolium perenne-Trifolium subterraneum Pasture under Differing Defoliation Treatments

Effects of defoliation frequency and intensity on persistence of a perennial ryegrass (Loliumperenne)-subclover (TrYohm subterraneum) pasture were studied near Corvallis, Ore., during 1980 to 1983. While canopy cover of individual plant species did not differ between defoliation frequency or intensity treatments (p6.05) within years, all defoliated plots differed from the undefoliated control plots. Canopy cover of perennial ryegrass declined from its initial value of 43% in 1980 to an average of 30% and 1% in defoliated and undefoliated plots in 1983, respectively. Perennial ryegrass in defoliated plots was apparently replaced by subclover, whose canopy cover increased by 33% during the j-year period. On undefoliated plots, however, both perennial ryegrass and subclover were replaced by annual grasses, whose canopy increased from approximately 2% in 1980 to 48% in 1983. Density of perennial ryegrass plants at the end of the trial in 1983 was highest when plots were defoliated once every 21 or 35 days compared to those defoliated every 7 days, 49 days, or the undefoliated control plots. Root biomass per plant, however, increased linearly as defoliation interval increased from 7 to 49 days between defoliation events. Viewed together, these data suggest that underutilization of grass-clover pastures may be potentially as damaging to pasture persistance as overutilization.

Attacks of Neodiprion sertifer on Pinus contorta1

Neodiprion sertifer, the European pine sawfly, has in the past attacked mainly Pinus sylvestris. Afforestation of areas in northern Scotland with P. contorta in the early 1960s and subsequently has led to widespread outbreaks of N. sertifer on this species, attacks being most severe on trees 5 to 12 years old. The most serious damage is removal of the 1‐year and older needles. Complete loss of this foliage often occurs at the peak of an outbreak. Also, at high population densities, larvae may consume patches of bark, leading to weakening and stem breakage in high winds. Field studies comparing protected (undefoliated) randomized plots of P. contorta with defoliated plots in Shin Forest (Sutherland) were carried out over the 1982–1983 growing seasons. Comparison of leaf/sapwood basal areas in undefoliated and defoliated plots indicated losses of up to 27% of total leaf area, both removal of old foliage by larvae and a reduction in current‐year foliage being involved. Further, there were significant reductions in sapwood basal area and height increment between control plots and some of the defoliated plots. The impact of such defoliation is to prolong the rotation by approximately 2 years.

The Influence of Gypsy Moth on the Composition and Nutrient Content of Litter Fall in a Pennsylvania Oak Forest

Abstract Litter fall was studied on gypsy moth (Lymantria dispar (L.))-defoliated plots and undefoliated plots in a Pennsylvania oak forest. Litter, collected throughout the year, was separated by plant and insect component and analyzed for dry weight and five major nutrients. Total biomass of litter falling on the defoliated and the undefoliated areas was not significantly different. Within the undefoliated plots, 90% of the litter was deposited during the autumn, and tree leaves were the major litter component. Major litter components within the defoliated plots included insect frass, leaf fragments, and tree leaves; 56% of the litter was deposited during the growing season. The nutrient content of litter totaled 73.1 kg/ha on the undefoliated plots, and tree leaves contributed 85% of all nutrients. The nutrient content of litter on the defoliated plots amounted to 94.6 kg/ha; leaf fragments, insect frass, and tree leaves contributed 34, 25, and 29% of all nutrients. Gypsy moth defoliation caused a statistically significant increase in the quantities of N, P, and K and a significant decrease in the quantity of Ca contained in litter fall. These differences are attributed to the gypsy moth altering the composition and seasonal distribution of litter fall. The significance of this nutrient shift is viewed as a further detriment to the health and vigor of host trees. Forest Sci. 32:855-870.

Effects of Defoliating Pests on Soybean Canopy CO2 Exchange and Reproductive Growth1

Defoliation during reproductive growth of soybean [Glycine max (L.) Merr.] may significantly reduce yields. The objective of this study was to elucidate the relationships among organism‐induced defoliation, CO2 exchange rates, and reproductive growth in fieldgrown soybean. Soybean (‘Bragg’) plots were sprayed a factorial design with diflubenzuron (0.035 kg a.i./ha) and a benomyl‐maneb mixture (1.12 a.i./ha) on two dates, first at early flowering (5 August) and again at early pod set (19 August). Diflubenzuron application prevented defoliation by velvetbean caterpillar (Anticarsia gemmatalis Hubner). By 12 September, LAI was reduced from 5.5 to 2.8, leaf dry weight from 185 to 110 g/m2, and midday light interception from 94 to 72% in defoliated as compared to non‐defoliated plots. While canopy specific leaf weight (SLW) increased in all treatments during the experimental period, SLW was 1.0 mg/cm2 higher in defoliated than non‐defoliated plots. On 4 September defoliated plots were sprayed with diflubenzuron (0.035 kg a.i./ha) and carbaryl (0.56 kg a.i./ha) prevent further leaf loss.Canopy CO2 exchange was measured at various photosynthetic photon flux densities (PPFD) to develop photosynthesis light response curves. Net canopy photosynthesis at 1,500 μE·m−2·sec−1 PPFD (PN1500) declined steadily in all treatments during seed growth. PN1500 and plant dark respiration, respectively, were reduced by 6.8 and 3.3 mg CO2·dm−2·hour−1 in defoliated compared to non‐defoliated plots. Soil CO2 efflux rates did not differ significantly (P &lt; 0.05) between treatments. Differences in pod growth rates (7.6 and 9.21 g·m−2·day−1 and yields (434 and 502 g·m−2) between defoliated and non‐defoliated plots, respectively, were attributed to differences in canopy photosynthetic capacity. There was no apparent effect of defoliation on seed growth duration or seed abortion. Rather, yield reduction in defoliated plots was related primarily to slowing of the individual seed growth rate. Balance of carbon flux to seeds showed relationships between instantaneous canopy CO2 exchange measurements and sequential harvest data.

Effect of partial defoliation during the vegetative phase on subsequent growth and grain yield of maize

SUMMARYMaize was grown in two densities, 2–47 or 4–94 plants m‐2, and the following treatments imposed: untreated, plants partly defoliated 51 days after sowing, and alternate plants in a row partly defoliated 44 days after sowing. Plants flowered about 82 days after sowing. Leaf area was decreased by 60–64% by defoliation on day 51.Defoliation resulted in decreases in grain yield and grain number of 6–17%, though when alternate plants were defoliated in the higher density there was a substantial decrease in yield and number of grains in defoliated plants, which was largely offset by an increase in adjacent intact plants.When plants were defoliated on day 51 subsequent growth in leaf area was similar to, and that in leaf weight nearly as large as that in untreated plants, while increase in stem weight was substantially less than in untreated plants. By the time of flowering untreated and defoliated plots differed by c. 30% in leaf area. Increments of dry matter after flowering differed by c. 15% between untreated and defoliated plots. The fraction of these increments which entered the grain was c. 90% in both untreated and defoliated plots.When alternate plants in the row were partly defoliated on day 44 their subsequent increase in leaf area was probably 5–16% less than that of the adjacent intact plants. Increments of dry matter after flowering of plots with alternate plants defoliated were 93–95 % of those of untreated plots; leaf efficiency after flowering was slightly greater than in untreated plots. The fraction of the dry matter increment after flowering which entered the grain was c. 88 % in both intact and defoliated plants of the small density, but was 94% in intact plants and 86% in defoliated plants of the large density.

Studies on the Ferreous Coating Formation in Roots of Rice Plants : (V) Ferreous coating formation in plants grown under abnormal conditions

As is previously reported, we have made clear that; (1) Ferreous coating formation (F. C. F.) in roots of rice plants proceeded parallely with nutrients absorption (N, P, and K) and production of the whole dry weigtht, (2) F. C. F. was closely correlated with the oxidation and sorption of Fe++ in media by roots, (3) Ferreous coating was mainly made with Fe++ oxidized and sorbed by roots and (4) The okidation and sorption of Fe++ were also influenced by Fe++ concentration in media. So far as it was concerned, physiological activities conducted by plant from the begining to a certain period of the growth may be proportionally recorded by F. C. F. measured at that period. This paper dealt with how F. C. F. is affected when plants are grown under abnormal conditions. Experiments are consisted of those mentioned below; (A) Effects of defoliation, (B) the same of leaf-blast infection, (C) the same of different soil temperatures, (D) the same of soils artificially deoxidized and (E) the same of nutrient deficiencies upon F. C. F., Fe++ oxidation and sorption in roots. F. C. F. in roots were washed away by 0.5 N-HCl and then colorimetrically determined by O-phenanthroline method. Fe++ oxidation and sorption by roots were estimated by determining concentration of Fe++ remained in FeSO4 solution, in which roots to be tested were soaked for 24 hrs. In addition, Fe++ concentrations in soils were also colorimetrically measured in filtrates, after soils were shaken with 1M CH3COONa solution. Main results obtained are as follows: (A) According to the grades of defoliation, F. C. F. in roots were either increased or decreased against non-defoliated (Fig. 1). The same resulted in Fe++ oxidation and sorption by roots (Fig. 2). In testing these physiological changes (Fig. 3), a temporaly rise of activities was found in defoliated plots. (B) When plants were infected by leafblast, F. C. F. in roots was also increased (Fig. 4). (C) The higher the soil temperature, the more F. C. F. in roots and Fe++ in soils were produced (Fig. 5). From this fact, F. C. F. in roots may be determined by amounts of Fe++ in soils. But as illustrated in Fig. 6, when Fe++ oxidation and sorption were measured, the higher temperature plot indicated higher physiological activities in contrast to the lower temperature and then activities decreased up to nearly equal values. From these it is clear that not only Fe++ amounts in soils but also the temperature affected F. C. F. in roots. (D) In artificially deoxidized soils, F. C. F. in roots of two varieties were similarly increased, notwithstanding the reduced plant growth (Fig. 7). (E) Nutrient deficiencies such as -N and -P made Fe++ oxidation and sorption in roots more active, but -K plot less active against complete nutrients plot (Fig. 8). This fact was obtained by using 30 days old seedling, but it was quite reverse when younger plants were used (Fig. 9). When abnormal conditions as mentioned above were given to plants, certain kinds of physiological activation or retardation may occur in infected or damaged parts, from where those effects may reach other parts, for instance, from top to roots. These facts were already recognized by some workers, just as activated or inactivated respiration in roots due to defoliation and others. From our results we can make an assumption again that such physiological changes happened in top or roots due to treatments may be recorded in the form of ferreous coating.