VTechWorks Repository :: Browsing by Author "Schmidt, Richard E."

Browsing by Author "Schmidt, Richard E."

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Competitive Effects of Perennial Ryegrass and Chewings Fescue on Bermudagrass Seed Establishment
Gooch, C. Bryan (Virginia Tech, 1998-04-02)
Perennial ryegrass (Lolium perenne L.) is widely used as a fairway turf on golf courses throughout the transition zone. The transition zone represents the geographical areas between the temperate and subtropical climates, where neither warm season nor cool season grasses are well adapted. The late-spring establishment of seeded bermudagrass could potentially enhance summer quality of a perennial ryegrass fairway during periods of extreme summer stress. Studies were conducted over two years on both perennial ryegrass and Chewings fescue (Festuca rubra L. ssp. commutata Gaud.) areas to assess the competitive effects of each species on bermudagrass seed establishment. The use of fungicides, herbicides and a plant growth regulator, as well as cultivation treatment prior to seeding, were evaluated for their effects on bermudagrass establishment, turfgrass quality, disease incidence and summer annual grass control. Turfgrass treated with preventative fungicide applications of propiconazole and chlorothalonil maintained high density and turf quality which inhibited successful establishment of bermudagrass during either year. Bermudagrass establishment in 1996 was moderately successful in plots not treated with fungicides; however, due to disease severity, turfgrass quality was unacceptable. MSMA applications did not influence turfgrass quality or bermudagrass establishment. Crabgrass populations were too low to ascertain the efficacy of either MSMA (1996) or oxadiazon (1997) on summer annual grass control. Oxadiazon followed by activated charcoal prior to bermudagrass seeding did not adversely affect bermudagrass establishment. In 1996, trinexapac-ethyl slightly enhanced bermudagrass seed establishment, but the competitiveness of perennial ryegrass prohibited establishment success. During 1997, glyphosate was evaluated as a means of eliminating competition and increasing bermudagrass establishment. Glyphosate applied in small strips across existing stands of perennial ryegrass and Chewings fescue significantly increased bermudagrass establishment. Preplant aerification and vertical mowing increased bermudagrass establishment, but slightly reduced turfgrass quality. Overall, bermudagrass establishment into existing stands of turfgrass was successful only where glyphosate was strip-treated over plots to eliminate competition or under circumstances where disease pressure reduced competition from the existing turfgrass.
The effect of seaweed concentrate on turfgrass growth, nematode tolerance and protein synthesis under moisture stress conditions
Sun, Hongwei (Virginia Tech, 1994)
A preliminary experiment was conducted to determine the effects of salinity and moisture stress on the pathogenicity of root-knot nematodes (RKN) in turfgrass plants. The results indicated that RKN infection adversely affected both visual and functional parameters of bentgrass. Salinity and moisture stress further exaggerated the damage caused by RKN. Under well-watered conditions, the effects of SWC and RKN infection on bentgrass plants were studied. Applications of Swe at 0.5 liter ha⁻¹ and 1.0 liter ha⁻¹ effectively enhanced bentgrass growth under both RKN-free and RKN-infected condition. It was shown that RKN caused less damage to SWC-treated plants than to non-treated plants. In addition, a soil drench of 0.5 liter ha⁻¹ and 1.0 liter ha⁻¹ at 10 day intervals was required to enhance bentgrass growth under RKN-free and RKN-infected conditions, respectively. The effects of seven SWC treatments on the growth of nematode-free and RKN infected bentgrass plants were tested under three irrigation regimes. Rooting and leaf moisture parameters, quality and clipping yield were all improved to some degree by SWC applications. High dosage SWC treatments, applied as a soil drench at one liter ha⁻¹ every 10 days, were most effective in improving plant growth. Application of SWC was more beneficial to RKN-infected plants than RKN-free plants, and to abiotically stressed plants than to abiotic stress-free plants. In a separate study, seaweed application was also shown to enhance both top growth and root growth of lance nematode (Hoplolaimus galeatus) or RKN infected bentgrass grown under drought or salinity stress condition. With SWC application, almost all of the symptoms caused by nematode infection and the abiotic stress were partially overcome. In addition, root development, leaf water status and clipping yield were all improved. It was apparent that soil drench SWC treatments were more effective in enhancing bentgrass growth than foliar Swc treatments. Application of SWC slightly reduced the number of nematodes per unit of fresh root (for RKN) and per unit weight of soil (for lance nematodes). Protein extracted from SWC-treated or non-treated ryegrass plants under different stress conditions indicated that SWC altered plant protein synthesis, possibly by inducing selective gene expressions.
Environmental and agronomic aspects of municipal solid waste heavy fraction used for turfgrass production
Flanagan, Mark Steven (Virginia Tech, 1991-01-15)
Disposal of municipal solid waste has become a tremendous problem in the United States. To reduce the volume of garbage that requires deposition in landfills, innovative methods of recycling need to be investigated. Several experiments were conducted in Blacksburg, Virginia, to evaluate the use of heavy fraction, a by-product of a solid waste separation process, as a soil amendment for production of turfgrass sod. In a field plot experiment using Kentucky bluegrass (Poa pratensis L.), measurements of sod strength taken 8.5 and 9.5 months after seeding were greater for sod grown in topsoil amended with heavy fraction than for turf grown in topsoil only. These results imply that the use of this by-product for turfgrass production may reduce the time required to produce a harvestable sod. In a container study, physical properties of a loam topsoil were altered 16 months after addition of heavy fraction. Bulk density and particle density were reduced and organic matter content increased by soil incorporation of this by-product. Total porosity and air porosity (macropore space) of the topsoil increased whereas water porosity (micropore space) decreased with increasing amount of applied heavy fraction. Soil fertility was enhanced and soil pH raised by addition of heavy fraction. Concentrations of extractable NH₄ -N, P, K, Ca, Mg, Mn, and Zn in soil were increased by the application of heavy fraction, as were concentrations of K, Ca, S, Mg, and Mn in leachate collected in lysimeter studies. Improved fertility resulted in greater aesthetic quality, clipping yields, and tissue N content for tall fescue (Festuca arundinacea Schreb.). Lysimeter studies indicated that the greatest environmental concern associated with the use of heavy fraction for turfgrass production appears to be the potential for leaching of N0₃-N during turf establishment. With loading rates of 414,747 kg ha⁻¹ or lower, however, the amount of N0₃-N leached from heavy fraction-amended topsoil was no greater than that leached from topsoil containing no heavy fraction. Concentrations of N0₃-N in leachate for all loading rates of heavy fraction decreased to levels well below 10.0 mg L ⁻¹ approximately two months after sodding the lysimeters with tall fescue. Leachate analyses indicated minimum potential for P or heavy metal contamination of groundwater from heavy fraction.
The evaluation of reserve carbohydrates in Midland Bermudagrass (Cynodon dactylon L.)
Burris, Joseph Stephen (Virginia Tech, 1965-05-07)
Examination of use of terminology using "carbohydrates" to describe reserve energy to plants.
Fertilización del Césped en Virginia
Goatley, Michael; Chalmers, David R.; Hall, John R.; Schmidt, Richard E. (Virginia Cooperative Extension, 2009-05-01)
This Spanish language version of Lawn Fertilization in Virginia discusses lawn fertilizers and best choices and practices for optimizing their use.
Influence of Acremonium coenophialum on Festuca arundinacea growth, chemical composition, digestibility and tall fescue toxicosis
Buttrey, Sherri A. (Virginia Polytechnic Institute and State University, 1989)
Infection of tall fescue (Festuca arundinacea Schreb.) with the endophyte fungus (Acremonium coenophialum, Morgan-Jones and Gam) has been associated with toxicity symptoms observed in cattle. The overall objective was to investigate the influence of endophyte infection on growth and chemical composition of tall fescue and the toxicity of endophyte-infected (EI) tall fescue to cattle. In a greenhouse study with pairs of genetically identical EI and non-infected (NI) ‘Kenhy’ tall fescue clones, concentration of N, Ca, Mg, Al, B, Mn and Zn was higher and K and S was lower in NI, compared to EI tall fescue. Insect resistance was higher in EI, compared to NI. Yield and chemical composition of high and low EI tall fescue were measured at four growth stages (stockpiled, prebloom, bloom and regrowth after harvest at bloom), two sites (Glade Spring and Blackstone) and three rates of N fertilization (0, 40 and 80 kg/ha) in a field study. Tall fescue grown at Glade Spring was higher in N, Mg, Al, Cu, Fe and Mn, compared to Blackstone. Nitrogen fertilization increased N, Mg, Ca, B, Cu, Na, Zn and decreased NDF, ADF, cellulose, P and S concentration in tall fescue. Neutral detergent fiber, ADF, cellulose, lignin, Fe and Na were higher in low, compared to high EI tall fescue. Concentrations of Cu, Na and Zn in stockpiled and Ca, Cu, Na and Zn in bloom-cut tall fescue hay were below dietary requirements for 227-kg steers. A disc meter was also evaluated for use in predicting yield of tall fescue. The meter is useful for non-destructive estimation of yield. Three feeding studies were conducted with steers (6/treatment/year). Diets were orchardgrass/alfalfa hay, spring-cut EI tall fescue hay, spring-cut EI tall fescue silage and fall-cut EI tall fescue silage. Serum prolactin and cholesterol were depressed in steers fed fescue hay and silages, compared to steers fed orchardgrass/alfalfa hay. Differences in mineral composition of hay and silage were reflected in serum minerals in steers. Ergopeptine alkaloids in EI tall fescue may have contributed to the depression of serum prolactin. The spring-cut silage contained the highest concentration of ergopeptine alkaloids, compared to other diets. Steers fed the spring-cut tall fescue silage had the lowest basal and thyrotropin-releasing hormone stimulated prolactin compared to steers fed the other diets.
Influence of iron and cytokinin on Cynodon spp. cultured at chilling temperatures
White, Richard Hampton (Virginia Polytechnic Institute and State University, 1985)
Bermudagrass (Cynodon spp.), when cultured at the northern limit of adaptation for semitropical grasses, is exposed seasonally to temperatures low enough to limit growth and turf quality. Research was conducted to investigate the influence of foliar iron and cytokinin applications on bermudagrass growth during fall and spring. The relationship of photosynthesis, respiration, and nonstructural carbohydrate composition to chilling temperatures was also studied. Foliar applications of Fe in late-summer and fall extended bermudagrass performance during low temperature periods of fall. Frequent Fe applications aided the retention of green bermudagrass turf during prolonged exposure to chilling temperatures. Iron applied the previous season stimulated post-dormancy recovery. Benzyladenine (BA) applied alone was not as effective as Fe for promoting green bermudagrass color retention during fall and BA had few effects on spring growth when applied the previous season. Applications of BA in conjunction with Fe were beneficial for retention of green bermudagrass color during late fall when clear plastic covers were used to prevent frost injury. A 6- to 8-week longer bermudagrass growing season occurred when clear plastic covers were used to prevent frost injury. Iron and BA did not significantly affect the total nonstructural carbohydrate (TNC) levels in Midiron bermudagrass rhizomes and stolons at the onset of dormancy in field studies. Midiron bermudagrass had higher photosynthetic and respiration rates than Tifgreen bermudagrass after 4 days exposure to chilling (10/7°C day/night) temperatures in controlled environment studies. Midiron recovered higher photosynthetic rates than Tifgreen when returned to a warm (30°C) environment after exposure to chilling temperatures. The TNC in leaves of Midiron and Tifgreen increased 88 and 160%, respectively, during 5 days at chilling temperatures. The inability to transport carbohydrate from and the subsequent accumulation of high photoassimilate levels in leaves was associated with the inability of bermudagrass to fully recover high photosynthetic rates following chilling. Reduced respiratory activity was apparently responsible for the accumulation of high TNC levels in leaves. In contrast to photosynthesis, respiration was reversibly inhibited by short term exposure of bermudagrass to chilling temperatures. Rapid recovery of high respiratory activity may be important for maintenance of aesthetically pleasing bermudagrass turf following chilling. Foliar applied Fe or BA generally caused darker green Midiron and Tifgreen turf after exposure to chilling temperatures in a controlled environment, although the enhancement of physiological activity differed with chemical applied and cultivar. Iron stimulated recovery of photosynthetic and respiratory activity in both cultivars after exposure to chilling temperatures. However, during chilling Midiron CO₂ exchange was more responsive to Fe applications. Benzyladenine increased photosynthesis in Tifgreen but not in Midiron and did not significantly affect respiration in either cultivar. Neither Fe nor BA had a consistent effect on TNC levels in bermudagrass leaves, rhizomes, or stolons. These investigations indicate that cultivar selection may play a major role in determining turf quality at chilling temperatures. Iron may modify bermudagrass physiology and enhance performance of bermudagrass exposed to chilling temperatures.
Influence of nitrogen, reduced irradience and biostimulants on turfgrass growth, superoxide dismutase content and chlorphyll fluorescence
Doak, Samuel O. (Virginia Tech, 1996-12-01)
Biostimulants (BIOS) are non-mineral substances that, when exogenously applied in very small quantities, stimulate the metabolic activity of plants. Past research with biostimulants has not included differing levels of nitrogen fertility or shade as variables. The research presented was designed to explore some interactions between biostimulants and nitrogen fertility on turfgrass grown under several light conditions.
Influence of Plant Growth Regulators on Turfgrass Growth, Antioxidant Status, and Drought Tolerance
Zhang, Xunzhong (Virginia Tech, 1997-07-01)
A series of studies were conducted to examine the antioxidant status, drought and disease tolerance, and growth response to foliar application of soluble seaweed (Ascophyllum nodosum) extracts (SE) and humic acid (HA; 25% active HA or 2.9% active HA) in tall fescue (Festuca arundinacea Schreb), Kentucky bluegrass (Poa pratensis L.) and creeping bentgrass (Agrostis palusttis Huds.) grown under low (-0.5 MPa) and high (-0.03 MPa) soil moisture environments. Foliar application of humic acid (2.9 % active HA) at 23.7 and 47.4 l/ha improved leaf water status, shoot and root development in tall fescue, Kentucky bluegrass and creeping bentgrass grown under drought. Humic acid (2.9% active HA) at 15.5 l/ha or SE at 326 g/ha significantly reduced dollarspot incidence and improved turf quality in creeping bentgrass. Drought stress induced an increase of antioxidants alpha-tocopherol and ascorbic acid concentrations in the three turfgrass species. In the experiment with Kentucky bluegrass, drought stress increased beta-carotene concentration, but did not significantly influence superoxide dismutase (SOD) activity. Foliar application of humic acid (25% active HA) at 5 l/ha and/or SE at 326 g/ha consistently enhanced alpha-tocopherol and ascorbic acid concentrations, leaf water status, and growth in the three cool-season turfgrass species grown under low and high soil moisture environments. In the experiment with Kentucky bluegrass, application of HA at 5 l/ha plus SE at 326 g/ha also increased beta-carotene content and SOD activity under low and high soil moisture environments. There were close positive correlations between the antioxidant status and shoot or root growth in the three turfgrass species regardless of soil moisture levels. The antioxidant SOD activity, photosynthetic capacity in terms of Fvm690, and chlorophyll content in terms of Fm730/Fm690 exhibited a seasonal fluctuation in endophyte [Neotiphodium coenophialum (Morgan Jones and Gams) Glenn, Bacon, Price and Hanlin] -free and endophyte-infected tall fescue. Application of SE enhanced SOD activity, photosynthetic capacity, and chlorophyll content in tall fescue, especially at 4 weeks after SE treatment. The SOD activity, photosynthetic capacity and chlorophyll content were not significantly influenced by the endophyte infection. A close positive correlation between SOD and photosynthetic capacity during the summer was found in endophyte-free and endophyte-infected tall fescue.
Influence of plant growth regulators on turfgrass polar lipid composition, tolerance to drought and salinity stresses, and nutrient efficiency
Yan, JiYu (Virginia Tech, 1993)
Two groups of plant growth regulators (PGRs), seaweed extract and triazole chemical, have been used in turfgrass management for improving turf quality and strengthening turfgrass tolerance to environmental stress. In order to understand the physiological functions and stress-tolerance mechanisms of the PGRs on turfgrass, a series of studies were conducted with perennial ryegrass (Lolium perenne L.). Ryegrass was treated with or without propiconazole (PPC) (1-( (2-(2,4- dichlorophenyl)-4-propyl-l,3-dioxolan-2yl)methyl) IH-l,2,4-triazole) and a proprietary fortified seaweed extract (FSE), which were combined with or without drought and salinity stress treatment. Total lipids, fatty acid composition of polar lipids, and total free and conjugated sterols were determined by the thin layer chromatograph, gas chromatograph, and scanner densitometer. This study indicates that ppe and FSE affected the unsaturation of polar lipid fatty acids and concentration of free sterols, which are major factors in changing cell membrane fluidity and permeability. The PGR-induced alteration of cell membrane lipid composition could be an adaptive process to protect plant membrane function under drought and salinity stresses. However, the metabolic effects of PPC and FSE may be different. It was found that PPC had a strong inl1uence on unsaturation of polar lipid fatty acids, whereas FSE had a strong effect on free sterol concentration. Furthermore, a radish cotyledon expansion bioassay analysis showed that the FSE had cytokinin or cytokinin-like activity and could stimulate endogenous cytokinins in ryegrass, whereas an inhibition of cell expansion was seen in PPC-treated plants. The possibility of using the PGRs to reduce fertilizer requirements was also studied. A higher uptake efficiency of most essential elements was found in PPC and FSE-treated Kentucky bluegrass (Poa pratensis L.) than in the control (without PGR treatments). This effect was greater at lower than at higher fertilization levels. The utilization efficiency of some major nutrient elements also was higher in PPC and FSE-treated bluegrass than in the control. The possibility of reducing fertilization by PGR application is positive.
Influence of seed and foliar applications of growth regulators on turfgrasses
Luo, Wang-Juan (Virginia Tech, 1991-01-05)
The effects of propiconazole and seaweed extract seed treatments on the germination of Kentucky bluegrass (Poa pratensis L.) under osmotic and temperature stresses were determined in the laboratory. As polyethylene glycol (PEG) 8000 concentrations was increased from 50 to 250 g/L, percent germination was reduced. Propiconazole at 0, 0.5, 0.9, and 1.9 g a.i./kg of seed did not affect total germination, however, germination was delayed with propiconazole seed treatment. Plumule and radicle lengths of seedlings at the termination of experiment 21 days were inhibited with increasing PEG 8000 concentrations and propiconazole treatments. Germination of seed treated with either propiconazole at 1.9 g a.i./kg of seed or seaweed extract at 13 g of product /kg of seed was determined under a range of temperatures from 15 to 40 C on a thermo gradient table. The optimum temperature for Kentucky bluegrass germination was at 25 C. Germination was decreased at temperature below 25 C and no germination was obtained at temperatures above 35 C. Seed treated with propiconazole or seaweed extract did not stimulate seed germination at the different temperatures.
Lawn Fertilization in Virginia
Goatley, Michael; Cataldi, Derik; Chalmers, David R.; Hall, John R.; Schmidt, Richard E. (Virginia Cooperative Extension, 2015-12-11)
Reviews the accurate application and placement of chemicals on lawns.
Lawn fertilization in Virginia
Chalmers, David R.; Hall, John R.; Schmidt, Richard E. (Virginia Cooperative Extension, 2000)
Lawn Fertilization in Virginia
Goatley, Michael; Chalmers, David R.; Hall, John R.; Schmidt, Richard E. (Virginia Cooperative Extension, 2009-05-01)
This publication reviews the accurate application and placement of chemicals on lawns.
Morphological and physiological growth responses of Kentucky bluegrass to foliar applications of iron, a cytokinin, and growth regulator- like chemicals
Goatley, James Michael (Virginia Polytechnic Institute and State University, 1988)
A series of studies were conducted to examine morphological and physiological responses of Kentucky bluegrass (Poa prazensis L.) following foliar applications of chelated iron phosphate citrate (Fe), the synthetic cytokinin benzyladenine (BA), the systemic triazole fungicides propiconazole and triadimefon, and MZ63 cold water seaweed extract. Applications of Fe at 112 mg m⁻², BA at 6 mg m⁻², propiconazole and triadimefon at 42 and 150 mg m⁻², respectively, and MZ63 seaweed extract at 0.32 ml m⁻² enhanced root and shoot growth and development of seedling Kentucky bluegrass. Repeated applications of BA, the triazoles, or MZ63 in late summer or fall and spring tended to slightly increase post-transplant rooting and sod strength of Kentucky bluegrass as compared to single applications. Repeated applications of Fe applied alone in late summer or fall and spring increased Kentucky bluegrass rooting as compared to single applications of Fe. However, the potential for reduced sod strength and post-transplant rooting was also indicated following single summer applications of chelated Fe at 112 mg m⁻². Kentucky bluegrass growth from various combinations of BA, the triazoles, MZ63 seaweed extract and Fe were highly variable. The nature of the responses indicated the possibility of an adverse interaction between the growth promoting activities of chelated Fe and the other materials. Kentucky bluegrass seedlings treated with Fe, BA, the triazoles, or MZ63 seaweed extract had increased photosynthetic rates on a land area basis, but not on a per gram shoot dry weight basis. These results suggested the larger photosynthetic rates were probably in response to an increased leaf area resulting from stimulation of leaf and lateral bud initiation. Benzyladenine was the most active material in delaying the senescence-like response of excised Kentucky bluegrass leaves as measured by carbon dioxide exchange, percent chlorophyll fluorescence decay, and leaf color ratings. Applications of Fe or propiconazole also delayed excision-induced senescence of Kentucky bluegrass leaves, while the anti-senescence activity of triadimefon was highly variable. Combinations of Fe with BA or the triazoles did not further promote a delay in excision-induced senescence.
Overseeded Bermudagrass Fairway Performance and Post Dormancy Transition as Influenced by Winter Overseeding Practices and Trinexapac-ethyl
Wharton, Samuel Matthew (Virginia Tech, 1999-12-03)
Dormant bermudagrass (Cynodon dactylon) fairways become matted down and thinned out from winter traffic. This appears to be more of a problem on the coarser textured, winter hardy, improved varieties (e.g., 'Midiron' and 'Vamont') typically used in the colder regions of the upper transition zone. Winter overseeding with cool-season species can improve dormant bermudagrass winter and spring quality. However, bermudagrass persistence can decline in golf course fairways overseeded with ryegrasses (Lolium sp.) for winter quality if ryegrasses persist due to cool spring temperatures, use of persistent ryegrass varieties, and management practices that favor ryegrasses over bermudagrass. Winter overseeding practices that facilitate a reliable transition from overseeded species to bermudagrass would enable transition zone golf courses to overseed bermudagrass fairways for winter-spring quality while allowing the bermudagrass turf to persist without excessive competition from cool-season overseeded species. Studies were conducted to determine the effects of perennial ryegrass (L. perenne) and annual ryegrass (L. multiflorum) seeding rates on winter-spring quality and subsequent transition to bermudagrass in two transition zone locations. Studies were also conducted to determine the potential influence trinexapac-ethyl (TE), a plant growth regulator used by many professional turfgrass managers to suppress foliar growth, has on encouraging overseeded species to transition to bermudagrass. These studies demonstrated that higher overseeding rates (448 and 896 kg ha-1) can provide greater winter-spring quality but do not enhance transition to bermudagrass over lower overseeding rates (224 kg ha-1). This was especially evident in cooler transition zone climate, where higher overseeding rates delayed transition to bermudagrass. Annual ryegrass transitioned to bermudagrass better than perennial ryegrass, but the overseeded winter-spring quality of annual ryegrass was unacceptable. Perennial ryegrass varieties differed in transition. Some perennial ryegrass varieties were too persistent to fully transition to bermudagrass even with the onset of summer temperatures. Intermediate ryegrasses (L. multiflorum x L. perenne) appeared to be promising alternatives to overseeding perennial ryegrass in areas of the transition zone where summer reliance on bermudagrass turf is strongly preferred. Trinexapac-ethyl, when applied to overseeded perennial ryegrasses, did not enhance overseeded ryegrass transition to bermudagrass. Spring TE applications to overseeded perennial ryegrasses were found to reduce or delay their transition to bermudagrass.
Responses of two grass species to plant growth regulators, fertilizer N, chelated Fe, salinity and water stress
Nabati, Daryoosh A. (Virginia Tech, 1991-11-15)
A series of studies were initiated to investigate growth responses of Kentucky bluegrass (Poa praetensis L.) and creeping bentgrass (Agrostis palustris Huds.) to foliar applications of two plant growth regulators (PGR) and/or chelated Fe (Na Fe diethylene triamine pentaacetate). Environmental variables considered were N levels, soil moisture regimes, and saline irrigations. The two materials investigated for PGR properties were a commercial product called Roots (a cold-water extract of seaweed and peat humus fortified with "intermediate metabolites" and thiamine) and the systemic fungicide propiconazole, trade name: (Banner) and chemical name: [1- {(2-(2,4-dichlorophenyl)-4-propyl-l,3-dioxolan-2yl}methyl-l H-1,2,4-triazole]. Fortified seaweed extract (FSE) was applied at 9.3 L/ha, and propiconazole (PPC) was applied at 0.93 L a.i/ha. Each was applied alone or in conjunction with chelated Fe at 0.11 kg a.i/ha. Kentucky bluegrass foliage height, root and shoot dry weight, and several foliar nutrients increased following PGR treatments when grown under either limited soil moisture or saline irrigation. Foliar applications of PGR and/or chelated Fe to creeping bentgrass reduced wilting and evapotranspiration, and increased leaf water status, root strength, and shoot dry matter at two levels of N during and after drought stress.
Some physiological responses of two grasses as influenced by temperature, light, and nitrogen fertilization
Schmidt, Richard E. (Virginia Polytechnic Institute, 1965)
Two environmental control chamber experiments were conducted to study the effects or temperature, nitrogen, and light intensity on the growth and physiological effects on Tifgreen bermudagrass, Cynodon dactylon (L) Pers., and Cohansey bentgrass, Agrostis palustris Huds. Each of the grasses was included in a field experiment to study the influence of nitrogen rates on carbohydrate reserves at different seasons. Increased temperatures with bentgrass caused decreased carbohydrates, root weights, and final growth of tops, but increased nitrogen content and respiration. NAR in bentgrass was highest at 75 F. The respiration rate, top growth, and carbohydrate content of bermudagrass tended to increase with temperature, but root weights and NAR were highest at medium temperatures. High N generally increased top growth, NAR, respiration, and nitrogen content, but lowered the carbohydrates and root growth for both grasses. Bentgrass, grown at 95 F during the day-, declined in yield, root growth, NAR, and respiration as night temperatures increased from 60 to 90 F. With bermudagrass HAR, top growth, and root growth were highest at 75 F and lowest at 90 F night temperatures. The AEC of bentgrass were highest at the mid-temperature, but the AEC: fer bermudagrass tended to increase with the high night temperature. Low light intensity generally decreased the yield of tops and roots, NAR, respiration, and carbohydrates, but increased the nitrogen content of both grasses. Bentgrass stolons increased in carbohydrate content during the tall and early vinter, and then declined rapidly during the spring. During the summer, the carbohydrates in bentgrass were low. The carbohydrates in bermudagrass stolons decreased during the winter and spring, increased during summer, and reached a maximum by late fall. For all experiments the oligosaccharides and monosaccharides made up a rather large portion of the AEC in bentgrass, polysaccharides being the largest fraction. Polysaccharides in bermudagrass made up the largest fraction of the AEC, the monosaccharides and oligosaccharides being less than 10% of the dry weight.
Tillering and carbohydrate content of orchardgrass as influenced by environmental factors
Auda, Hamid (Virginia Tech, 1964-06-05)
Experiments were conducted in the field, greenhouse, and controlled environment chambers to study the effect of environmental factors on tillering, growth, and carbohydrate content of orchardgrass. Tillers of one genotype were studied with several variable factors (light, temperature, moisture,. nitrogen, and/or defoliation) in each of four experiments. Factorial treatment combinations were used in each of the four experiments to study single factors and interactions. Tillering declined to 73 and 26% of normal light when light intensity was reduced in the greenhouse and field, respectively. In the controlled environment chambers, tillering rates were higher with an 18-hour than for a 9-hour day with 3100 F.C. in both chambers. Soluble carbohydrates in the stubble were associated with tillering. There was a marked increase in water soluble carbohydrates as light energy increased up to normal sunlight. Ory matter production was associated with tillering and carbohydrate contents of orchardgrass, factors which increased tillering augmented clipping dry weights. Tillering and foliage growth were much higher when day temperature was 80*F. as compared with 60°F. There was a sharp increase in soluble carbohydrates with low temperature, but at the high temperature carbohydrates did not accumulate as they were apparently utilized for fast growth and tillering. Carbohydrate accumulation per se was not associated with tillering nor yields when temperatures were sub~-optimum for fast growth. Tillering was increased 30% by irrigation. Tillering of orchardgrass plants, defoliated to 1.5, 3, and 6 inches in combination with other treatments, showed increased tillering and dry matter production as defoliation intensities were relaxed. High tillering rates were associated with the magnitude of carbohydrates in orchardgrass stubble. Root development at the end of the experiment was much poorer for intensive defoliation as compared with lax defoliation. Nitrogen stimulated tillering and retarded soluble carbohydrate accumulation in orchardgrass stubbles, Nitrozen stimulated the production of new tissue and nitrogen compounds at the expense of stored carbohydrates in the stubbles. With slow orchardgrass growth under low nitrogen, soluble carbohydrates in the stubble accumulated. There was good evidence that soluble carbohydrates are directly associated with tillering and growth of orchardgrass when factors such as light, nitrogen, and water do not limit growth. Carbohydrate accumulatpeiro nse is not associated with tillering, if any environment growth factor is sub-optimum for tillering and growth. sub-optimum for tillering and growth.

Browsing by Author "Schmidt, Richard E."

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