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D.a. Schisler - One of the best experts on this subject based on the ideXlab platform.
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soil bacteria selected for suppression of rhizoctonia solani and growth promotion in Bedding Plants
Soil Biology & Biochemistry, 1994Co-Authors: A.r. Harris, D.a. Schisler, Raymond L Correll, M.h. RyderAbstract:Abstract Over 5000 bacterial isolates were obtained by dilution plating of potting media that were suppressive to damping-off disease caused by Rhizoctonia solani AG 8 in seedlings of Celosia argentea . These isolates were screened for inhibition ofAG 8 in vitro , then 91 selected isolates were screened further for their ability to suppress the effects of R. solani AG 8 in seedlings of Capsicum annuum and Celosia argentea grown in pasteurized potting medium in a glasshouse. Fourteen isolates selected from the above screenings then were screened similarly for suppression of damping-off caused by R. solani AG 4 in seedlings of Capsicum, Celosia, Petunia and Viola . Three isolates reduced disease more consistently than the others. B. subtilis A13, an isolate previously reported to control R. solani in Bedding Plants, did not reduce damping-off in any host plant species. These three isolates were compared in two experiments over a range of doses for growth promotion, and suppression of AG 4, in Capsicum . Although there were few dose responses, when data for all dose rates were combined, all isolates increased dry weights of Capsicum shoots in the absence of R. solani . In one of the experiments, all but one isolate also increased seedling survival in the absence of R. solani . Two bacterial isolates and the fungicide quintozene reduced damping-off caused by AG 4. The selected bacterial isolates exhibit potential for biological suppression of damping-off in Bedding Plants in nursery potting media.
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Suppression of damping-off caused by Rhizoctonia solani, and growth promotion, in Bedding Plants by binucleate Rhizoctonia spp
Soil Biology & Biochemistry, 1994Co-Authors: A.r. Harris, D.a. Schisler, S.m. Neate, M.h. RyderAbstract:Abstract Nine isolates of binucleate Rhizoctonia spp, from potting media and nursery Plants, were screened for their ability to control damping-off disease caused by Rhizoctonia solani Kuhn AG 4 and AG 8. Seedlings of Capsicum annuum L. were grown in a pasteurized potting medium in growth chambers. All isolates prevented damping-off caused by R. solani AG 4, and most isolates increased shoot weights in the presence of either AG 4 or AG 8. Two isolates were tested further on seedlings grown in pasteurized potting medium in a glasshouse. In two experiments, both isolates controlled damping-off in Capsicum caused by AG 4. In another experiment, both isolates reduced damping-off caused by AG 4 in Capsicum, Celosia and Viola seedlings, and increased shoot weights of Capsicum and Celosia. One isolate also reduced damping-off in Petunia. Each isolate promoted shoot growth of seedlings in two of four experiments when no pathogen was added. As these binucleate Rhizoctonia isolates also control Pythium, they have potential for use as biological control agents in plant nurseries.
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Bacteria suppress damping-off caused by Pythium ultimumvar. Sporangiiferum, and promote growth, in Bedding Plants
Soil Biology and Biochemistry, 1994Co-Authors: A.r. Harris, D.a. Schisler, M.h. Ryder, P.g. AdkinsAbstract:Abstract Fifteen isolates of bacteria, from potting media collected from South Australian plant nurseries and potting mix suppliers, were screened for ability to control damping-off disease caused by Pythium ultimum var. sporangiiferum. The screening was by two bioassays on seedlings of Capsicum annuum grown in a pasteurized potting medium in a glasshouse or controlled environment growth chamber. Ten isolates reduced damping-off and increased shoot weights, at least as well as the fungicide propamocarb, in both experiments. Eight isolates also reduced damping-off in seedlings of Celosia argentea in another glasshouse experiment, and all 14 isolates tested increased shoot weights, but propamocarb had no significant effect on damping-off or shoot weight. In another glasshouse experiment, four bacterial isolates were applied at five different doses to pasteurized potting medium with or without P. u. sporangiiferum. Capsicum seedlings were assayed for shoot growth and suppression of damping-off. In the presence of Pythium, only one bacterial isolate showed a dose-response in seedling survival and shoot weights, but another isolate reduced damping-off equally at all doses. In the absence of Pythium, all bacterial isolates increased shoot dry weights, but there were no responses to increased doses of bacteria. Bacillus subtilis A13 suppressed damping-off in only one of four experiments.
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Characteristics of some Rhizoctonia spp. from South Australian plant nurseries
Mycological Research, 1994Co-Authors: G. Masuhara, S.m. Neate, D.a. SchislerAbstract:Forty-nine Rhizoctonia isolates were obtained from nursery Plants, potting mix, vegetable seedlings and Bedding Plants in South Australia. Of these isolates, 75% were binucleate Rhizoctonia and 25% were multinucleate. Anastomosis tests showed that all of the multinucleate isolates were either Rhizoctonia solani AG-2-1 or AG-4 and that the binucleate Rhizoctonia belonged to either AG-F, AG-I, AG-K and CAG-5 or to four other groups of isolates which did not anastomose with the known isolates tested. Teleomorphs of 14 isolates were induced and were identified as Thanatephorus cucumeris, Ceratobasidium cornigerum, C. pseudocornigerum and two unknown species Ceratobasidium . Extracellular pectic enzyme patterns were not useful in determining likely anastomosis groups for the binucleate Rhizoctonia .
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the occurrence and pathogenicity of rhizoctonia fungi in south australian plant nurseries
Fungal Biology, 1994Co-Authors: D.a. Schisler, S.m. Neate, G. MasuharaAbstract:Potting mixes and Plants exhibiting symptoms of root disease were collected from 30 nurseries or potting mix suppliers in South Australia. Thirty-nine isolates of Rhizoctonia were obtained from 11 sampling locations by isolating from diseased Plants, planting media, or by isolating from the roots of bait seedlings (zinnia, brussels sprouts, radish, bell pepper, wheat and ornamental lupin) grown in the planting media. Thirty-five isolates were binucleate and four were multinucleate. Binucleate isolates anastomosed with known groups AG-A, AG-I, AG-K or CAG 5 and 10 were not able to be placed in any known group. Multinucleate isolates belonged to AG-2-1 and AG-4. Certain AG-4 multinucleate isolates reduced the growth of wheat or bell pepper while certain binucleate isolates decreased the growth of wheat or increased the growth of bell pepper. Although multinucleate Rhizoctonia fungi can cause severe disease of Bedding Plants, it is difficult to predict such damage due to the influence of potting mix edaphic factors and variability in pathogenicity of the isolates present.
M.h. Ryder - One of the best experts on this subject based on the ideXlab platform.
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soil bacteria selected for suppression of rhizoctonia solani and growth promotion in Bedding Plants
Soil Biology & Biochemistry, 1994Co-Authors: A.r. Harris, D.a. Schisler, Raymond L Correll, M.h. RyderAbstract:Abstract Over 5000 bacterial isolates were obtained by dilution plating of potting media that were suppressive to damping-off disease caused by Rhizoctonia solani AG 8 in seedlings of Celosia argentea . These isolates were screened for inhibition ofAG 8 in vitro , then 91 selected isolates were screened further for their ability to suppress the effects of R. solani AG 8 in seedlings of Capsicum annuum and Celosia argentea grown in pasteurized potting medium in a glasshouse. Fourteen isolates selected from the above screenings then were screened similarly for suppression of damping-off caused by R. solani AG 4 in seedlings of Capsicum, Celosia, Petunia and Viola . Three isolates reduced disease more consistently than the others. B. subtilis A13, an isolate previously reported to control R. solani in Bedding Plants, did not reduce damping-off in any host plant species. These three isolates were compared in two experiments over a range of doses for growth promotion, and suppression of AG 4, in Capsicum . Although there were few dose responses, when data for all dose rates were combined, all isolates increased dry weights of Capsicum shoots in the absence of R. solani . In one of the experiments, all but one isolate also increased seedling survival in the absence of R. solani . Two bacterial isolates and the fungicide quintozene reduced damping-off caused by AG 4. The selected bacterial isolates exhibit potential for biological suppression of damping-off in Bedding Plants in nursery potting media.
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Suppression of damping-off caused by Rhizoctonia solani, and growth promotion, in Bedding Plants by binucleate Rhizoctonia spp
Soil Biology & Biochemistry, 1994Co-Authors: A.r. Harris, D.a. Schisler, S.m. Neate, M.h. RyderAbstract:Abstract Nine isolates of binucleate Rhizoctonia spp, from potting media and nursery Plants, were screened for their ability to control damping-off disease caused by Rhizoctonia solani Kuhn AG 4 and AG 8. Seedlings of Capsicum annuum L. were grown in a pasteurized potting medium in growth chambers. All isolates prevented damping-off caused by R. solani AG 4, and most isolates increased shoot weights in the presence of either AG 4 or AG 8. Two isolates were tested further on seedlings grown in pasteurized potting medium in a glasshouse. In two experiments, both isolates controlled damping-off in Capsicum caused by AG 4. In another experiment, both isolates reduced damping-off caused by AG 4 in Capsicum, Celosia and Viola seedlings, and increased shoot weights of Capsicum and Celosia. One isolate also reduced damping-off in Petunia. Each isolate promoted shoot growth of seedlings in two of four experiments when no pathogen was added. As these binucleate Rhizoctonia isolates also control Pythium, they have potential for use as biological control agents in plant nurseries.
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Bacteria suppress damping-off caused by Pythium ultimumvar. Sporangiiferum, and promote growth, in Bedding Plants
Soil Biology and Biochemistry, 1994Co-Authors: A.r. Harris, D.a. Schisler, M.h. Ryder, P.g. AdkinsAbstract:Abstract Fifteen isolates of bacteria, from potting media collected from South Australian plant nurseries and potting mix suppliers, were screened for ability to control damping-off disease caused by Pythium ultimum var. sporangiiferum. The screening was by two bioassays on seedlings of Capsicum annuum grown in a pasteurized potting medium in a glasshouse or controlled environment growth chamber. Ten isolates reduced damping-off and increased shoot weights, at least as well as the fungicide propamocarb, in both experiments. Eight isolates also reduced damping-off in seedlings of Celosia argentea in another glasshouse experiment, and all 14 isolates tested increased shoot weights, but propamocarb had no significant effect on damping-off or shoot weight. In another glasshouse experiment, four bacterial isolates were applied at five different doses to pasteurized potting medium with or without P. u. sporangiiferum. Capsicum seedlings were assayed for shoot growth and suppression of damping-off. In the presence of Pythium, only one bacterial isolate showed a dose-response in seedling survival and shoot weights, but another isolate reduced damping-off equally at all doses. In the absence of Pythium, all bacterial isolates increased shoot dry weights, but there were no responses to increased doses of bacteria. Bacillus subtilis A13 suppressed damping-off in only one of four experiments.
A.r. Harris - One of the best experts on this subject based on the ideXlab platform.
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soil bacteria selected for suppression of rhizoctonia solani and growth promotion in Bedding Plants
Soil Biology & Biochemistry, 1994Co-Authors: A.r. Harris, D.a. Schisler, Raymond L Correll, M.h. RyderAbstract:Abstract Over 5000 bacterial isolates were obtained by dilution plating of potting media that were suppressive to damping-off disease caused by Rhizoctonia solani AG 8 in seedlings of Celosia argentea . These isolates were screened for inhibition ofAG 8 in vitro , then 91 selected isolates were screened further for their ability to suppress the effects of R. solani AG 8 in seedlings of Capsicum annuum and Celosia argentea grown in pasteurized potting medium in a glasshouse. Fourteen isolates selected from the above screenings then were screened similarly for suppression of damping-off caused by R. solani AG 4 in seedlings of Capsicum, Celosia, Petunia and Viola . Three isolates reduced disease more consistently than the others. B. subtilis A13, an isolate previously reported to control R. solani in Bedding Plants, did not reduce damping-off in any host plant species. These three isolates were compared in two experiments over a range of doses for growth promotion, and suppression of AG 4, in Capsicum . Although there were few dose responses, when data for all dose rates were combined, all isolates increased dry weights of Capsicum shoots in the absence of R. solani . In one of the experiments, all but one isolate also increased seedling survival in the absence of R. solani . Two bacterial isolates and the fungicide quintozene reduced damping-off caused by AG 4. The selected bacterial isolates exhibit potential for biological suppression of damping-off in Bedding Plants in nursery potting media.
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Suppression of damping-off caused by Rhizoctonia solani, and growth promotion, in Bedding Plants by binucleate Rhizoctonia spp
Soil Biology & Biochemistry, 1994Co-Authors: A.r. Harris, D.a. Schisler, S.m. Neate, M.h. RyderAbstract:Abstract Nine isolates of binucleate Rhizoctonia spp, from potting media and nursery Plants, were screened for their ability to control damping-off disease caused by Rhizoctonia solani Kuhn AG 4 and AG 8. Seedlings of Capsicum annuum L. were grown in a pasteurized potting medium in growth chambers. All isolates prevented damping-off caused by R. solani AG 4, and most isolates increased shoot weights in the presence of either AG 4 or AG 8. Two isolates were tested further on seedlings grown in pasteurized potting medium in a glasshouse. In two experiments, both isolates controlled damping-off in Capsicum caused by AG 4. In another experiment, both isolates reduced damping-off caused by AG 4 in Capsicum, Celosia and Viola seedlings, and increased shoot weights of Capsicum and Celosia. One isolate also reduced damping-off in Petunia. Each isolate promoted shoot growth of seedlings in two of four experiments when no pathogen was added. As these binucleate Rhizoctonia isolates also control Pythium, they have potential for use as biological control agents in plant nurseries.
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Bacteria suppress damping-off caused by Pythium ultimumvar. Sporangiiferum, and promote growth, in Bedding Plants
Soil Biology and Biochemistry, 1994Co-Authors: A.r. Harris, D.a. Schisler, M.h. Ryder, P.g. AdkinsAbstract:Abstract Fifteen isolates of bacteria, from potting media collected from South Australian plant nurseries and potting mix suppliers, were screened for ability to control damping-off disease caused by Pythium ultimum var. sporangiiferum. The screening was by two bioassays on seedlings of Capsicum annuum grown in a pasteurized potting medium in a glasshouse or controlled environment growth chamber. Ten isolates reduced damping-off and increased shoot weights, at least as well as the fungicide propamocarb, in both experiments. Eight isolates also reduced damping-off in seedlings of Celosia argentea in another glasshouse experiment, and all 14 isolates tested increased shoot weights, but propamocarb had no significant effect on damping-off or shoot weight. In another glasshouse experiment, four bacterial isolates were applied at five different doses to pasteurized potting medium with or without P. u. sporangiiferum. Capsicum seedlings were assayed for shoot growth and suppression of damping-off. In the presence of Pythium, only one bacterial isolate showed a dose-response in seedling survival and shoot weights, but another isolate reduced damping-off equally at all doses. In the absence of Pythium, all bacterial isolates increased shoot dry weights, but there were no responses to increased doses of bacteria. Bacillus subtilis A13 suppressed damping-off in only one of four experiments.
Erik S. Runkle - One of the best experts on this subject based on the ideXlab platform.
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ethephon substrate drenches inhibit stem extension of floriculture crops
Hortscience, 2012Co-Authors: William B. Miller, Danghui Xu, Christopher J Currey, Kasey L Clemens, Michael Olrich, Neil S Mattson, Roberto G. Lopez, Erik S. RunkleAbstract:Ethephon ((2-chloroethyl) phosphonic acid) is a plant growth regulator that releases ethylene on application and can abort flowers, stimulate branching, and inhibit stem elongation. Although ethephon is used as a foliar spray during the commercial production of many ornamental crops, its effectiveness as a drench has not been widely investigated. We performed experiments to quantify the effects of an ethephon drench on growth and flowering of a range of Bedding plant and Narcissus cultivars and to assess the effect of lime on ethylene release from a peat substrate. A substrate drench of 0, 100, 250, or 500 mg·L L1 ethephon was applied to 12 potted Narcissus cultivars at one location, and up to 200 mg·L L1 was applied to 24 cultivars of Bedding Plants at three locations. Compared with untreated controls, ethephon generally reduced plant height atflowering and the effect increased with increased concentration. For example, Narcissus treated with a 250 mg·L L1 ethephon drench had stems that were 20% to 40% shorter at the end of flowering than control Plants. However, ethephon drenches generally caused a 2- to 3-day flowering delay, and two cultivars had a phytotoxic response. Among the Bedding Plants studied, a 100-mg·L L1 ethephon drench suppressed plant height at flowering by greater than 30% in Catharanthus, Celosia, Dianthus, and Verbena, but by only 10% to 15% in Lobelia, Lycopersicon, and Tagetes. The drenches also delayed flowering in 10 of the 16 crops measured and decreased dry mass accumulation in all of the crops measured. Ethephon release from peat substrate became maximal '120 h after application and was dramatically increased by incorporation of dolomitic lime up to a rate of 9.5 kg lime per m 3 of peat. Collectively, these studies show that ethephon substrate drenches inhibit stem elongation in a broad range offloriculture crops, but can also delay flowering and reduce biomass accumulation.
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the influence of day and night temperature fluctuations on growth and flowering of annual Bedding Plants and greenhouse heating cost predictions
Hortscience, 2011Co-Authors: Matthew G Blanchard, Erik S. RunkleAbstract:Volatile energy costs and lower profit margins have motivated many greenhouse growers in temperate climates to improve the energy efficiency of crop production. We performed experiments with dahlia (Dahlia xhybrida Cav. 'Figaro Mix'), French marigold (Tagetes patula L. 'Janie Flame'), and zinnia (Zinuia elegans Jacq. 'Magellan Pink') to quantify the effects of constant and fluctuating temperatures on growth and flowering during the finish stage. Plants were grown in glass-glazed greenhouses with a day/night (16 h/8 h) temperature of 20/14, 18/18, 16/22 (means of 18 °C), 24/18, 22/22, or 20/26 °C (means of 22 °C) with a 16-h photoperiod and under a photosynthetic daily light integral of 11 to 19 mol·m ―2 ·d ―1 . Flowering times of dahlia, French marigold, and zinnia (Year 2 only) were similar among treatments with the same mean daily air temperature (MDT). All species grown at 20/14 °C were 10% to 41% taller than those grown at 16/ 22 °C. Crop timing data and computer software that estimates energy consumption for heating (Virtual Grower) were then used to estimate energy consumption for greenhouse heating on a per-crop basis. Energy costs to produce these crops in Charlotte, NC, Grand Rapids, MI, and Minneapolis, MN, for a finish date of 15 Apr. or 15 May and grown at the same MDT were estimated to be 3% to 42% lower at a +6 °C day/night temperature difference (DIF) compared with a 0 °C DIF and 2% to 90% higher at a -6 °C DIF versus a 0 °C DIF. This information could be used by greenhouse growers to reduce energy inputs for heating on a per-crop basis.
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quantifying the thermal flowering rates of eighteen species of annual Bedding Plants
Scientia Horticulturae, 2011Co-Authors: Matthew G Blanchard, Erik S. RunkleAbstract:Abstract The effect of mean daily air temperature (MDT) on flowering rate (the reciprocal of days to flower) was quantified for 18 species of annual Bedding Plants. Plants were grown in environmental growth chambers at constant air temperature set points of 5, 7.5, 10, 15, 25, or 30 °C and under an irradiance of 160–180 μmol m –2 s –1 , with a 16-h photoperiod. Nonlinear mathematical equations were developed to predict the effect of MDT on flowering rate and to estimate the base, optimum, and maximum temperatures ( T min , T opt , and T max ), which are the temperatures at which flowering rates are zero (low temperature), maximal, and zero once again (high temperature), respectively. The estimated T min varied among species and ranged from 1.1 °C in French marigold ( Tagetes patula L.) to 9.9 °C in angelonia ( Angelonia angustifolia Benth.). T opt and T max were only observed for 8–10 species with the temperature range tested. T opt ranged from 19.1 °C in dahlia ( Dahlia × hybrida Cav.) to 28.0 °C in blue salvia ( Salvia farinacea Benth.), whereas T max ranged from 30.3 °C in snapdragon ( Antirrhinum majus L.) to 31.7 °C in moss rose ( Portulaca grandiflora Hook.). Angelonia, browallia ( Browallia speciosa Hook.), cosmos ( Cosmos sulphureus Cav.), dahlia, and snapdragon grown at 25 or 30 °C developed a mean of two to seven more nodes before flowering compared with Plants grown at ≤15 °C. The results indicate that in many species, flowering rate in response to MDT is asymmetrical around T opt and the temperature range between T min and T opt is wider than that between T opt and T max . This information could be used to improve the predictability of flowering time of these ornamental crops and to assist growers in determining energy-efficient production temperatures.
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influence of nir reflecting shading paint on greenhouse environment plant temperature and growth and flowering of Bedding Plants
Transactions of the ASABE, 2010Co-Authors: Matthew G Blanchard, Erik S. RunkleAbstract:During greenhouse production, growers often utilize shading strategies to reflect shortwave radiation (SWR; 300 to 2,700 nm) and reduce the thermal load inside a greenhouse. Greenhouse glazing or shading materials that photoselectively filter more near-infrared radiation (NIR; 770 to 2,700 nm) than photosynthetically active radiation (PAR; 400 to 700 nm) can be used to reduce thermal energy transmission. We quantified environmental conditions and Bedding plant growth and flowering inside a glass-glazed greenhouse (lat. 42.7° N) that received an application of either a commercially available NIR-reflecting (NIR-R) or neutral (N) shading paint. During two summer seasons, shading paints were applied to the glazing exterior of different greenhouses so that the mean daily transmission of PAR was similar. Poinsettia (Euphorbia pulcherrima Willd. ex Klotz) or Bedding Plants were grown inside each greenhouse. The NIR-R paint transmitted 67%, 8%, 24%, 30%, and 29% less ultraviolet-A (315 to 380 nm), red (R; 600 to 700 nm), far-red (FR; 700 to 800 nm), NIR, and SWR, respectively, than the N paint. Transmission of blue (400 to 500 nm) and green (500 to 600 nm) light was 4.7% and 4.5% greater, respectively, under the NIR-R versus N paint. The ratio of transmitted PAR per unit of SWR under the N and NIR-R paints was 1.8 and 2.6 µmol W-1 s-1, respectively. During the day (1100 to 1800 h), mean greenhouse air, shoot-tip, and leaf temperatures were 0.4°C to 1.5°C, 0.4°C to 1.2°C, and 0.7°C to 1.5°C higher, respectively, under the N paint compared with the NIR-R paint. From 0900 to 1700 h, the ratio of R to FR light under the NIR-R paint ranged from 1.44 to 1.79, whereas the N paint and outside the greenhouse had an R:FR ratio of 1.11 to 1.22. Blue salvia (Salvia farinacea Benth.), pansy (Viola × wittrockiana Hook.), and petunia (Petunia ×hybrida Vilm.-Andr.) flowered a mean of 1 to 3 d earlier under the N versus NIR-R paint, but plant heights were similar.
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photosynthetic daily light integral during the seedling stage influences subsequent growth and flowering of celosia impatiens salvia tagetes and viola
Hortscience, 2005Co-Authors: Lee Ann Pramuk, Erik S. RunkleAbstract:Additional index words. Bedding Plants, marigold, pansy Abstract. The photosynthetic daily light integral (DLI) dramatically increases during the spring when the majority of Bedding Plants are commercially produced. However, the effects of DLI on seedling growth and development have not been well characterized for most Bedding plant species. Our objectives were to quantify the effects of DLI on growth and development of Celosia, Impatiens, Salvia, Tagetes, and Viola during the seedling stage and determine whether there were any residual effects of DLI on subsequent growth and development after transplant. Seedlings were grown in growth chambers for 18 to 26 days at 21 °C with a DLI ranging from 4.1 to 14.2 mol·m -2 ·d -1 . Average seedling shoot dry weight per internode (a measure of quality) increased linearly 64%, 47%, 64%, and 68% within this DLI range in Celosia, Impatiens, Tagetes, and Viola, respectively. Seedlings were then transplanted to 10-cm containers and grown in a common environment (average daily temperature of 22 °C and DLI of 8.5 mol·m -2 ·d -1 ) to determine subsequent effects on plant growth and development. Flowering of Celosia, Impatiens, Salvia, Tagetes, and Viola occurred 10, 12, 11, 4, and 12 days earlier, respectively, when seedlings were previously grown under the highest DLI compared with the lowest. Except for Viola, earlier fl ower- ing corresponded with the development of fewer nodes below the fi rst fl ower. Flower bud number and plant shoot dry weight at fi rst fl owering (plant quality parameters) decreased as the seedling DLI increased in all species except for fl ower number of Tagetes. Therefore, seedlings grown under a greater DLI fl owered earlier, but plant quality at fi rst fl owering was generally reduced compared with that of seedlings grown under a lower DLI.
S.m. Neate - One of the best experts on this subject based on the ideXlab platform.
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Suppression of damping-off caused by Rhizoctonia solani, and growth promotion, in Bedding Plants by binucleate Rhizoctonia spp
Soil Biology & Biochemistry, 1994Co-Authors: A.r. Harris, D.a. Schisler, S.m. Neate, M.h. RyderAbstract:Abstract Nine isolates of binucleate Rhizoctonia spp, from potting media and nursery Plants, were screened for their ability to control damping-off disease caused by Rhizoctonia solani Kuhn AG 4 and AG 8. Seedlings of Capsicum annuum L. were grown in a pasteurized potting medium in growth chambers. All isolates prevented damping-off caused by R. solani AG 4, and most isolates increased shoot weights in the presence of either AG 4 or AG 8. Two isolates were tested further on seedlings grown in pasteurized potting medium in a glasshouse. In two experiments, both isolates controlled damping-off in Capsicum caused by AG 4. In another experiment, both isolates reduced damping-off caused by AG 4 in Capsicum, Celosia and Viola seedlings, and increased shoot weights of Capsicum and Celosia. One isolate also reduced damping-off in Petunia. Each isolate promoted shoot growth of seedlings in two of four experiments when no pathogen was added. As these binucleate Rhizoctonia isolates also control Pythium, they have potential for use as biological control agents in plant nurseries.
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Characteristics of some Rhizoctonia spp. from South Australian plant nurseries
Mycological Research, 1994Co-Authors: G. Masuhara, S.m. Neate, D.a. SchislerAbstract:Forty-nine Rhizoctonia isolates were obtained from nursery Plants, potting mix, vegetable seedlings and Bedding Plants in South Australia. Of these isolates, 75% were binucleate Rhizoctonia and 25% were multinucleate. Anastomosis tests showed that all of the multinucleate isolates were either Rhizoctonia solani AG-2-1 or AG-4 and that the binucleate Rhizoctonia belonged to either AG-F, AG-I, AG-K and CAG-5 or to four other groups of isolates which did not anastomose with the known isolates tested. Teleomorphs of 14 isolates were induced and were identified as Thanatephorus cucumeris, Ceratobasidium cornigerum, C. pseudocornigerum and two unknown species Ceratobasidium . Extracellular pectic enzyme patterns were not useful in determining likely anastomosis groups for the binucleate Rhizoctonia .
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the occurrence and pathogenicity of rhizoctonia fungi in south australian plant nurseries
Fungal Biology, 1994Co-Authors: D.a. Schisler, S.m. Neate, G. MasuharaAbstract:Potting mixes and Plants exhibiting symptoms of root disease were collected from 30 nurseries or potting mix suppliers in South Australia. Thirty-nine isolates of Rhizoctonia were obtained from 11 sampling locations by isolating from diseased Plants, planting media, or by isolating from the roots of bait seedlings (zinnia, brussels sprouts, radish, bell pepper, wheat and ornamental lupin) grown in the planting media. Thirty-five isolates were binucleate and four were multinucleate. Binucleate isolates anastomosed with known groups AG-A, AG-I, AG-K or CAG 5 and 10 were not able to be placed in any known group. Multinucleate isolates belonged to AG-2-1 and AG-4. Certain AG-4 multinucleate isolates reduced the growth of wheat or bell pepper while certain binucleate isolates decreased the growth of wheat or increased the growth of bell pepper. Although multinucleate Rhizoctonia fungi can cause severe disease of Bedding Plants, it is difficult to predict such damage due to the influence of potting mix edaphic factors and variability in pathogenicity of the isolates present.