Crown Tissue Research Articles

Persistence and effects of apple mosaic virus on cultured normal and crown gall apple tissue and in cucumber tissue

Persistence and effects of apple mosaic virus on cultured normal and crown gall apple tissue and in cucumber tissue

EVALUATION OF FACTORS AFFECTING YIELD REDUCTION IN MATURE ALFALFA (Medicago sativa L.)

Alfalfa (Medicago sativa L.) stand longevity continues to be a problem even though progressive management practices are followed. The following parameters were evaluated on mature alfalfa stands to determine what factors were responsible for stand thinning: forage production, stand density, foliar and crown-root diseases, root and crown tissue weights, and total nonstructural carbohydrate levels. Foliar diseases did not affect stand density; however, three of five anthracnose-resistant cultivars had denser stands than susceptible parents. Fusarium infection was quite high but did not appear to be related to stand density. Individual root weight, root mass, and total nonstructural carbohydrates were not good indicators of stand density.Key words: Alfalfa stand longevity, foliar diseases, crown and root rot, root and crown tissue weight, total nonstructural carbohydrates, forage production

Cultivar and Management Effects on Stand Persistence of Birdsfoot Trefoil1

AbstractInteractions between growth habit and management of birdsfoot trefoil (Lotus corniculatusL.) are reported by other researchers to affect stand persistence. Stand persistence dependent on the longevity of plants within the stand can be confused with the persistence of stand resulting from natural reseeding in this crop. A field test of 10 birdsfoot trefoil cultivars differing in growth habit was planted in May 1979 on Mexico silt loam (Fine, montmorillinitic, mesic Udollic Ocharqualf) near Columbia, Mo. Commencing April 1980, effects of four management treatments on stand persistence were studied to determine the degree of emphasis to be given to growth habit in a program of genetic improvement for trefoil persistence. Volunteer seedling establishment was controlled with simazine [2‐chloro‐4,6‐bis(ethylamino)‐s‐triazine]. Significantly lower herbage yields in stockpiled and unharvested managements were attributed to foliar blight caused by Rhizoctonia solaniKeuhn. Stand persistence, based on plant counts, was observed to be independent of management since plants within stands behaved more like biennials than perennials regardless of management. Cultivar by management effects on stand persistence were not significant (P>0.05). An average stand reduction of 90% was observed from April 1980 to 1982. Greatest reductions in stand counts were observed each year between April and October. An average disease score of 2.4, where 0 indicated root and crown tissues visibly free of decay and 5 indicated extensive decay, was obtained from 939 surviving plants examined in April 1982. Poor stand persistence could be explained in part by the foliar, crown, and root diseases found at the study site. Lack of differences in stand persistence and tolerance to disease may reflect the close ancestry of the entries tested. Emphasis on growth habit in a genetic improvement program for persistence in the Southern Corn Belt appeared less important than an examination of genetic resources for lowered susceptibility to disease.

An Adaptive Response of Rye to Freezing1

An increase in intercellular solute of crown tissue was induced by keeping hardened plants frozen at −3°C for 24 h. This environmental condition commonly occurs because of temperature stabilization from latent heat released as soil water freezes. The amount of intercellular solute in crown tissues was estimated from the concentration of liquid that, when perfused through the plant crown at 1°C, was found, by successive approximations, to be isotonic with the intercellular liquid. The intercellular content of ‘Rosen’ rye (Secale cereale L.) increased by factor of 3.0 to 3.5 when frozen 24 h at −3°C; then at 1°C, the concentration gradually decreased to that of nonfrozen plants. Recovery occurred in less than 1 h at 25°C. The increase of intercellular solute content occurred as a function of time at −3°C. ‘Hudson’ barley (Hordeum vulgare L.) which contains less intercellular solute than Rosen rye after freezing at −3°C, and Rosen rye in which the intercellular solute was reduced by flushing, were less hardy than Rosen rye tested with the normal 24‐h prefreeze at −3°C.

Effect of Seedborne Fusarium moniliforme and Irrigation Scheduling on Colonization of Root and Stalk Tissue, Stalk Rot Incidence, and Grain Yields1

Eighty percent of the 486 000 ha of corn production in Kansas is irrigated and Fusarium stalk and root rots (primarily incited by Fusarium moniliforme Sheld.) is the most damaging diseases of irrigated corn with estimated annual statewide losses ranging from 5 to 10%. The purpose of this study was to investigate the effects of seedborne, airborne, and soilborne F. moniliforme inoculum and irrigation scheduling on F. moniliforme colonized root and crown tissue, grain yields and stalk rot incidence. Parameters included four levels (0, 12.5, 25, and 50%) of F. moniliforme infested seed lots and four irrigation schedules: 1) non‐irrigated; 2) irrigating when the available soil moisture was 50% depleted as determined by a neutron probe; 3) 50% depleted as determined by a computer model; and 4) 35% depletion until tasseling, then 65% until harvest as determined by a computer model. Colonization of the root and crown tissue by F. moniliforme increased nearly three‐fold during the growing season as the fungus was detected in 23.1% of the corn plants in May and 62.5% in August. Fungal colonization of plant tissue could not be correlated to infested seed lots or irrigation schedules. Stalk rot incidence and grain production were not significantly influenced by the various levels of infested seed lots. Yields were increased nearly 85% with a concomitant decrease (59.8%) stalk rot incidence in the irrigated plots. The highest levels of soilborne inoculum (210 propagules/g of soil) and airborne inoculum (0.3 propagule/L of air) were found near the end of the growing season.

Effects of allelopathic substances produced by asparagus on incidence and severity of asparagus decline due toFusarium crown rot

The effects of toxic components isolated from asparagus tissue onFusarium spp. and other soil microorganisms and their effects on the susceptibility of asparagus toFusarium crown rot was investigated to determine what role allelopathic substances may play in the asparagus ecosystem and in asparagus crown rot decline. Dried sterilized asparagus crown and root tissues were incorporated into pots of 3-month-old asparagus seedlings with and withoutFusarium inoculum. Root tissue alone and treatments in which crown and root tissues were combined with theFusarium inoculum showed significant reduction of plant growth over nontreated controls. Root and crown tissues were partitioned with polar and nonpolar solvents and bioassayed on pregerminated asparagus and cress seeds. Inhibition of radicle growth was confined to the polar fractions. Further separation with paper chromatography gave several fractions that were inhibitory to radish, cress, tomato seed germination as well as inhibitory to growth of pregerminated asparagus seeds. Crude extracts from roots and crown residues were bioassayed on many different fungal isolates on Petri plates and were found to inhibit the growth of oomycetous fungi. Extracts from the roots were found to be more active than extracts from other portions of the asparagus plants.

Interactions among Flooding, Freezing, and Ice Encasement in Winter Wheat

Exposure of winter wheat (Triticum aestivum L.) to various combinations of flooding and freezing stresses induces much greater damage than the individual stresses. Cold-hardened plants flooded for 1 week or exposed to -6 degrees C for 1 week show 100% survival, while survival of plants exposed to both stresses simultaneously is reduced by 20 to 30%, and cold hardiness decreases by several degrees. The level of nonstructural carbohydrates increases in crown tissue during cold acclimation, but decreases when the plants are exposed to flooding or to -6 degrees C for 1 week. The respiratory capacity of crown tissue segments declines when the plants are stressed. Uptake of (86)Rb by the roots of intact seedlings declines after exposure to either freezing or flooding, whereas passive efflux of amino acids is observed after freezing but not following flooding. This study has shown that detectable stress-induced metabolic changes occur in winter wheat before the applied stress is severe enough to reduce survival.

Factors influencing the effectiveness of Trichosirocalus horridus (Panzer) in the control of Carduus thistles

Trichosirocalus horridus (Panzer) (Coleoptera: Curcilionidae), a European weevil introduced for the biological control of Carduus thistles, was initially released in 1974 and has become established in Virginia, USA. Studies were conducted to examine the impact of the weevil on Carduus thistles in the field in spring and winter, and in the laboratory. Variables included two thistle species, two thistle sizes and three larval densities. Response of the thistle to larval infestation was influenced by thistle growth, thistle size and larval density. Thistle rosettes grown in the laboratory had the greatest percentage of plants developing necrosis (99%) with none recovering fully; the plant centre died in 89%, and 31% died completely, whereas no field-grown plants died. Spring rosettes developed the next largest percentage of necrosis (85%) and of death of centre (28%), but had the highest percentage of plants recovering (80%). Overwintering thistles developed the least amount of necrosis (43%) and of dead centres (2%), but had a lower recovery rate (61%) than spring thistle rosettes. Neither spring nor overwintering rosettes died even at the highest infestation level (50 larvae). Appearance of symptoms of infestation in overwintering thistle rosettes was influenced by plant species, plant size and rate of larval infestation. Thistle species was not a factor determining when laboratory rosettes manifested symptoms of infestation, and larval density did not influence spring rosettes. Small laboratory thistle rosettes were killed by infestations of 30 larvae (42%) and 50 larvae (100%). Although T. horridus larvae do not kill the majority of the thistles that they infest, they do weaken them by destroying crown tissues. The effectiveness of T. horridus may be greatly enhanced by the joint use of other stress factors.

Freezing Resistance and Cold Acclimation in Turfgrasses1

Abstract The freezing resistance of leaf, crown, and root tissues was determined for nonhardened and cold-hardened cultivars of perennial rye (Lolium perenne L.), Kentucky bluegrass (Poa pratensis L.), and red and chewings fescues (Festuca rubra L. and F. rubra var. commutata Gaud.). The nonhardened leaf and crown tissues of all the cultivars studied survived temperatures below –9.8°C. After acclimating at 5° under short days for 6 weeks or longer, the maximum increase in hardiness was in ‘Wintergreen’ (chewings fescue) which survived –27°. The cold-acclimation behavior of ‘Wintergreen’ was studied at acclimating temperatures of 0° and 5°. Both the leaf and crown tissues had at least 2 stages of acclimation, in which an acclimating temperature of 5° was conducive to the initial stage, followed by a lower acclimating temperature (0°) for the second stage.

A comparative study of membrane related phenomena in normal and crown gall tissues of red beet (Beta vulgaris L.)

Divalent metal ions have been found to protect membranes of red beet crown gall tissue more than their adjacent normal regions from thermal or gamma radiation stress, suggesting the possibility of an alteration on the surface charge accompanying tumor formation in plants. Further, tumor tissue has been observed to possess enhanced membrane ATPase activity, a higher tissue sulfhydryl content and increased protein levels, thus suggesting a model of ‘source’ (normal tissue) and ‘sink’ (tumor tissue) relationship.

Changes in carbohydrate levels during ice encasement and flooding of winter cereals

Carbohydrate levels and production of ethanol and malic acid were followed in the acclimated crown tissue of four cereal cultivars during ice-encasement and low-temperature-flooding treatments. Tolerance to both anaerobic stresses ranked as 'Lutescens 230' wheat > 'OAC Wintri' triticale > 'Fredrick' wheat > 'Siete Cerros' wheat. All cultivars produced more ethanol during flooding than icing treatments. The winter cereal cultivars, 'Lutescens 230,' 'OAC Wintri,' and 'Fredrick,' produced significantly more ethanol than the spring wheat, 'Siete Cerros,' but consistent differences among the winter cultivars were not observed. Malic acid was not accumulated after 7 days icing or 14 days flooding. The quantity of total available carbohydrate, total ethanol-soluble carbohydrate, and reducing sugars in the crown tissue was highest in those cultivars with high icing and flooding tolerance. In addition, the most tolerant cultivar, 'Lutescens 230,' had a greater rate of carbohydrate utilization during stress treatment than the other cultivars. Nevertheless, the loss of plant viability after ice encasement of flooding was not associated with the depletion of carbohydrate reserves. Icing was a more severe stress than flooding, and differences are indicated in the utilization of carbohydrate reserves and production of ethanol during the two stresses.

Crested Wheatgrass Vigor as Affected by Black Grass Bug and Cattle Grazing

Crested Wheatgrass Vigor as Affected by Black Grass Bug and Cattle Grazing

Starch-enhanced synthesis and release of amylolytic enzymes from normal and crown gall tumor tobacco tissue culture cells

The response of tobacco crown gall tumor cells growing in tissue culture to a substitution of starch for sucrose as the carbon source in the medium was compared with the response of normal tobacco tissue culture cells. In both cases amylolytic activity was secreted into the medium. The increase in extracellular amylolytic activity was preceded by an increase in intracellular activity. The increase in intracellular amylolytic enzymes was sensitive to cycloheximide and to actinomycin D indicating that enzyme induction at the level of mRNA synthesis was required. No significant difference between the responses of normal and tumor cells was observed. Thus crown gall tumor cells were as capable as normal cells of sensing and responding to an alteration in the carbon source in the external medium.

Combined Nitrogen and Vegetative Regrowth of Symbiotically‐grown Alfalfa1

AbstractFew studies clearly compare N source effects on herbage yield of alfalfa (Medicago sativa L.) grown with Rhizobium over several harvest cycles. Therefore, the effects of combined N on nodulation, growth, N accumulation, and development of alfalfa were studied over four harvest/regrowth cycles with a genotype cloned from the nondormant cv. ‘Dohfari.’ Ramets inoculated with Rhizobium meliloti Dang. strain 102F28 and irrigated with 0,2,8, or 16 mM N provided as NH4NO3, NO3‐, or NH4+ were grown in vermiculite in a naturally illuminated greenhouse in two replicate experiments from March through June and July through October. All combined N treatments enhanced herbage dry weight and total crude protein above the nil N control during the first growth period. The promotive effect of combined N decreased with each harvest until during the fourth regrowth, plants totally dependent on Rhizobium for reduced N produced herbage and crude protein yields equivalent to plants supplied 8 or 16 mM N as NH4NO3. Plants grown with 2mM N, a more reasonable N concentration for the soil solution, were more productive than nil N plants during the first two growth cycles but had no advantage during the third and fourth cycles regardless of the form of combined N used. Nitrate suppressed nodule development more than either NH4NO3 or NH4+. Greater availability of combined N increased the soluble sugar:starch ratio in the root and crown tissues. No significant differences were observed between the two experiments except that plants grown later in the year (July to October) took longer to flower during each regrowth cycle.The data indicate that the Rhizobium symbiosis cannot produce sufficient reduced N for optimum alfalfa growth during the first few harvest/regrowth cycles. During subsequent regrowth cycles, however, plants totally dependent on Rhizobium for N compounds had overcome the period of N‐limited growth and produced as much herbage and crude protein as plants grown with levels of combined N that might be expected under normal field conditions.

FALL GROWTH AND COLD ACCLIMATION OF WINTER WHEAT AND RYE ON SALINE SOILS

The effect of salt stress during the period of cold acclimation for winter wheat (Triticum aestivum L.) and rye (Secale cereale L.) was studied in field trials on saline soils north of the Quill Lakes in the northeastern corner of the agricultural area of Saskatchewan. Shoot and crown dry weights and crown moisture, sodium, magnesium and sulfur contents were all strongly influenced by variables related to soil conductivity. Increased levels of soil sodium and magnesium salts were reflected by increased concentrations of sodium, magnesium and sulfur in the crown tissue. In contrast, crown calcium content decreased significantly with increased soil salinity. Soil salinity had a variable effect on cold hardiness. Although the general trend was towards reduced cold tolerance of plants with increased salt stress, reductions were not large enough to be of practical concern.

Trace element levels in red spruce and the effect of age, crown and seasonal changes

Abstract The trace element content of red spruce foliage exhibits seasonal changes which vary with the crown position, tree and tissue age and the particular element considered. Tree age has a significant effect on trace element content while crown position has a less striking influence. New foliage growth, when compared to year old needles, also exhibits differences. The mean levels of trace elements contained in red spruce foliage ranged from 1231–1915 ppm manganese, 32.8–50.8 ppm iron, 14.5–18.4 ppm boron, 5.5–6.6 ppm copper, 52–88 ppm aluminum, 19.0–26.6 ppm zinc and 0.023–0.030 ppm molybdenum.

A Method for Rating Freezing Inhibitor Activity of Barley Genotypes Using Seed and Crown Tissue Mucilages1

An infrared assay is described for rating activity of cell wall mucilages as inhibitors of freezing kinetics. It requires 1% of the sample needed for the flow freeze assay previously used to rate mucilages extracted from wheat seed (Triticum aestivum L.). The reduction of sample size makes it feasible to assay polymers from crown tissue in genetic and plant breeding research. This is especially important for barley (Hordeum vulgare L.) because assay of seed extracts does not reliably indicate inhibitor activity in crown tissue for this species.Mucilages from both seed and crown tissues of eight Ethiopian barleys, Introduced into the USDA World Collection as possible sources of genetic diversity, were compared with those from a commercial barley. The introductions did produce more mucilage in their seed than did the commercial barley but did not produce effective inhibitors of freezing kinetics in their crowns.

Response of Several Sugarbeet Cultivars to N Fertilization: Yield and Crown Tissue Production1

AbstractThe level of plant available N greatly affects sugarbeet (Beta vulgaris L.) quality, sucrose production, and the amount of lower quality crown ussue produced. The response of several sugarbeet cultivars to N fertilization was studied in 1977 and 1978 to determine: i) what level of available N was needed by each cultivar to maximize sucrose production; ii) if each cultivar would respond similarly to N fertilization; and iii) if crown tissue production varies with cultivar. Nitrogen rates from 0 to 448 kg/ha were used as main plots with three to five commercially‐grown sugarbeet cultivars as subplots in the study. Root and sucrose yield, sucrose content, clear juice purity, and crown tissue production were determined for each treatment. All sugarbeet cultivars tested responded similarly to increasing levels of available N with crown tissue growth increasing linearly, sucrose content and clear juice purity decreasing linearly, and whole root yield increasing curvilinearly. Addition of some N fertilizer was needed to maximize sucrose production; however, as the level of N fertilization increased above the N level needed for maximum sucrose production, sucrose production decreased. Root tissue growth and sucrose production were maximum at the same N level, but maximum sucrose production did not coincide with maximum whole root yield. Sucrose production was maximum at the same N level for all cultivars. Thus, sugarbeet producers need not vary N fertilizer rates for each sugarbeet cultivar grown. However, total amount of sucrose production per unit area and crown growth did vary with cultivar. At optimum N fertilization, crown tissue accounted for 12 to 17% of the whole root yield, depending on year and cultivar grown. Results of this study indicate that N fertilization influences sugarbeet quality, crown tissue production, and level of sucrose production more than does sugarbeet cultivar.

Sclerophthora macrospora: The Incitant of Yellow Tuft Disease of Turf Grasses

JACKSON, N., and P. H. DERNOEDEN. 1980. Sclerophthora macrospora: The incitant of yellow tuft disease of turf grasses. Plant Disease 64:915-916. were used. Two soil pH levels were included because of a report that pH may affect zoospore germination (5). Cylinders containing five seeds of each species were placed on both soils in sufficient number to allow three replications of each of four inoculum treatments designated 0, X, 2X, and 3X using zoospores from Agropyron repens. Inoculum comprising 0.5 ml of zoospore suspension (about 10,000 spores) was withheld (0), applied once (X), twice (2X), or three times (3X) over a 3-day period to the appropriate cylinders. The water level in the soil containers (and hence in the cylinders) was held just above the level of the seeds during this period, and the temperature was maintained at 15 C. After 3 days, excess water was drawn off, and the seedlings were placed under diffuse light on a window bench at prevailing laboratory temperatures. Infection of the plants was determined after 2-3 wk by inspecting leaf and/or crown tissue with a microscope for the presence of the distinctive S. macrospora mycelium (4). Tissues were cleared in boiling 5% potassium hydroxide solution,

Influence of Nitrogen Fertility Level and Topping Method on Yield, Quality, and Storage Losses in Sugarbeets1

AbstractThe recovery of sucrose from sugarbeets (Beta vulgaris L) has decreased in recent years while root yield has increased. Our objective was to determine the effect of N application rate and topping method on root yield and on the factors affecting recovery of sucrose‐sucrose content, purity, and storage loss.The effect of five N fertility levels (0, 67, 134, 202, and 269 kg/ha) on sugarbeet root yield, quality (percent sucrose and percent purity) and crown tissue size was investigated from 1975‐1977 in 10 field experiments in Colorado, Kansas, and Nebraska. Crown tissue, the portion of the sugarbeet above the lowest leaf scar, increased from 10.64 to 16.03% of the total root weight as the N application rate increased from 0 to 260 kg/ha. Total root yield increased from 45.2 to 54.4 metric tons/ha over the same N range, but much of the yield increase was due to increase in crown size. Sucrose content and clarified juice purity (CJP) decreased 1.42 and 1.97% units, respectivdy, as the N application went from 0 to 269 kg/ha. The decrease in quality offset the increase in yield so that increasing rates of N had no significant effect upon yield of recoverable sucrose per ha. The extractable sucrose per metric ton of beets was reduced from 144.5 kg/ton for the 67 kg N/ha application to 128.6 kg/ton for the 269 kg N/ha application. Crown removal significantly reduced yield of recoverable sucrose per hectare but only increased extractable sucrose per ton from 136.7 to 140.0 kg/ton.Quality (sucrose and CJP) was improved both by proper topping and by N management, however, N management has a more dramatic effect upon quality. Total sucrose yield is reduced by topping, but not significantly affected by N application rate.Three N fertility levels (0, 134, and 269 kg/ha) and three topping methods (flailed, half‐topped, and topped) were evaluated for their effect on sucrose and quality changes in sugarbeet roots during storage in nine experiments. Failed beets had 27.4 and 25.5% less gross sucrose and recoverable sucrose losses than regular topped beets and 17.3 and 15.7% less gross suaose and recoverable sucrose lass than half‐topped beets. Method of topping had a significant effect upon sucrose losses in beets grown in all Iri levels. Nitrogen application rate had no significant effect upon gross sucrose or recoverable sucrose losses.Beet quality (extractable sucrose per metric ton) was higher in topped beets than flailed beets at harvest, but no difference existed between topping treatments after storage. Sucrose production per acre and beet quality was maximized with the low fertility, flailed treatments before and after storage.