34 research outputs found
Biology and management of freesia flower specking caused by Botrytis cinerea
No full textThere is no published research regarding postharvest infection of freesia flowers
by Botrytis cinerea. Although, infection problems have concerned freesia growers and
wholesalers in recent years. The overall objectives of this study were firstly to evaluate
the factors affecting B. cinerea postharvest disease establishment and secondly to
evaluate a range of novel potential treatments to reduce postharvest freesia infection.
These treatment options include plant activators such as acibenzolar-S-methyl and methyl
jasmonate and biotic (Aureobasidium pullulans) and abiotic (UV-C irradiation)
biological/elicitors agents.
Research was undertaken in an attempt to explain the variation in B. cinerea
incidence on cut freesia flowers as noted by the UK importer Zwetsloots & Sons Ltd. in
2000. Higher monthly rejections of freesia flower stems throughout 2000 due to B.
cinerea infection were recorded during spring (April-May), early summer (June) and
autumn (October). Comparatively higher proportions of rejected freesia stems were
associated with glasshouse temperatures ranging from 13-17°C.
In the presence of B. cinerea inoculum on freesia petal surface, temperature was
not a limiting factor for disease establishment. Incubation of artificially inoculated
freesia flowers at 12°C resulted in overall higher disease severity and lesion numbers
compared to flowers incubated at 5 or 20°C. In contrast, relative humidity was the most
important factor for postharvest infection by B. cinerea.
Elicitor based strategies for IPM using the potent activator acibenzolar provided
limited protection of freesia flowers against B. cinerea when applied postharvest.
Acibenzolar significantly reduced disease severity, lesion numbers and lesion diameters
compared to the untreated control when applied at 0.15 g A. 1. U1.
Methyl jasmonate (MeJA) applied as gas, pulse and spray generally suppressed B.
cinerea disease on cut freesia flowers. Disease severity, lesion numbers and lesion
diameters of flowers gassed with 0.1 μL MeJA L"' were reduced by 56,43 and 37%,
respectively compared to untreated control flowers. Gaseous MeJA treated freesia
flowers at 0.1 μL L"1 increased PPO activity by 57% compared to untreated controls 24h
after MeJA treatment. After 36h of incubation at 20°C, disease severity, lesion numbers and lesion diameters of gaseous MeJA treated flowers were reduced by 68,56 and 50%,
respectively, compared to the untreated controls. However, PAL activity in MeJA treated
freesia flowers did not decrease significantly over time compared to untreated control 12h
post-inoculation and thereafter. These findings suggest that MeJA treatment might
suppress the action of PAL in the phenylpropanoid pathway and consequently block SA
production.
UV-C irradiation might be used in an integrated postharvest disease management
program for freesia flowers. UV-C irradiation after artificial inoculation resulted in
markedly reduced B. cinerea disease severity scores and lesion numbers. In detail, UV-C
irradiation of cut freesia flowers with 0.5,1,2.5 and 5 kJ m''` reduced disease severity by
up to 44,70,74 and 59% and lesion numbers by up to 37,62,68 and 60%, respectively.
UV-C irradiation at 1 kJ M-2 before artificial inoculation slightly reduced disease severity
and lesion numbers possibly by inducing defence responses. However, the limited
disease suppression suggested that apparently B. cinerea could overcome the UV-C
induced effect.
The effect of preharvest treatments on freesia crops with acibenzolar was
investigated in glasshouse trials in view to suppress postharvest B. cinerea infection via
SAR induction. Acibenzolar was effective in selected treatments and conditions.
Disease pressure varied over the 3 years and over varieties tested. However, it was
unclear whether acibenzolar induced systemic and/or local defence responses. The latter
was supported by biochemical investigations in 2001 which suggested that acibenzolar
did not induce PAL activity.
In contrast, preharvest MeJA treatment resulted in markedly systemic protection
of treated flowers compared to untreated ones. MeJA efficacy was dependent on variety
and on postharvest incubation temperatures. Disease severity, lesion numbers and lesion
diameters on MeJA treated freesia var. `Dukaat' flowers incubated at 20°C were reduced
by 56,61, and 49% compared to controls, respectively. Also, disease severity, lesion
numbers and lesion diameters on MeJA treated `Cote d'Azur' flowers incubated at 20°C
were reduced by 36,26, and 49% compared to controls, respectively
Implementation of Sustainable Practices to Ornamental Plant Cultivation Worldwide: A Critical Review
No full textOrnamental production worldwide has changed dramatically in the past 20 years. A globalized scene has shifted production to new countries from Africa, Asia, and South America. Sustainability is the major challenge for ornamental production, and the life cycle assessment (LCA) provides insights on environmental contributions from production to handling and transportation and highlights the problematic issues that need improvement. For example, greenhouse gas (GHG) emissions and the production costs of roses in different parts of the world may vary dramatically between different production processes (e.g., heated or non-heated greenhouses, with or without air transportation, etc.). On the other hand, the production of landscape plants has the lowest environmental impact of all floricultural products. Their long production period offers carbon sequestrations that reduce the total GHG emissions. Sustainability is achieved via critical adjustments on cultivation by minimizing fuel and electricity use, adopting integrated nutrient management (INM) and integrated pest and disease management (IPDM), and using recyclable materials and peat-alternative growing compounds. In this review, two possible scenarios were proposed for ornamental production. Scenario I suggests conventional, protected cultivation under controlled environments (i.e., greenhouses), which can be sustainable after implementing appropriate adjustments to reduce environmental outputs. Scenario II suggests the cultivation of native and specialty ornamental crops, which may serve as eco-friendly alternatives. Combinations between the two scenarios are also possible in view to implement sustainable practices and meet future consumer needs
UV-C irradiation induces defence responses and improves vase-life of cut gerbera flowers
No full textPostharvest UV-C irradiation on cut Freesia hybrida L. inflorescences suppresses petal specking caused by Botrytis cinerea
No full textPostharvest petal specking caused by Botrytis cinerea is a major concern for freesia growers and sellers in Holland and the UK. Germicidal and inducible host defence effects of UV-C irradiation were evaluated. UV-C irradiation of freesia inflorescences after artificial inoculation with B. cinerea (i.e. the germicidal effect) was more effective in reducing petal specking, compared to UV-C treatment before artificial inoculation (i.e. the defence induction effect). Cut freesia inflorescences exposed to 1 kJ m(-2) UV-C after artificial inoculation with 104 B. cinerea conidia mL(-1) displayed reduced disease severity scores, lesion numbers and lesion diameters by 74, 68 and 14%, respectively, compared to non-irradiated control inflorescences. In contrast, UV-C irradiation with I kJ m(-2) before artificial inoculation reduced lesion numbers and lesion diameters by 13 and 24%, compared to the non-irradiated controls. Higher UV-C doses of 2.5 or 5 kJ m(-2) reduced disease severity scores, lesion numbers and lesion diameters when applied after artificial inoculation, but enhanced disease when applied before artificial inoculation. Vase life of cut freesia inflorescences irradiated with 0.5, 1 or 2.5 kJ m(-2) UV-C was maintained equal to non-irradiated controls. However, 5 kJ m(-2) resulted in phytotoxicity evident as petal discoloration and reduced vase life compared to non-irradiated inflorescences. (C) 2009 Elsevier B.V. All rights reserved
Las obras rupestres de Huarimio, Tierra Caliente de Michoacán. 28. Arqueología
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Evaluation and improvement of post-harvest performance of cut Viburnum tinus inflorescence
No full textEffects of Brief UV-C Irradiation Treatments on Rooting Performance of Pelargonium × hortorum (L.H. Bailey) Stem Cuttings
No full textPelargonium × hortorum (L.H. Bailey), is a South African native ornamental plant with worldwide commercial recognition used in gardens and terraces. In the present study, we evaluated the effects of low doses of UV-C irradiation on rooting performance of P. × hortorum stem cuttings. We also tested the hypothesis that UV-C-induced ethylene production directly interacted with rooting process. Over a 40 d evaluation period, the ethylene production of the UV-C-treated stem cuttings was significantly increased. UV-C irradiation positively affected rooting performance. Rooting percentage was increased in the UV-C-irradiated stem cuttings by up to 17%, time to rooting was decreased by 15% (e.g., 5 d) and root weight increased by 17% compared to the nonirradiated controls. UV-C irradiation did not affect net CO2 assimilation (As), but it induced transpiration (E) on the 14, 20, 22 and 24 d of the evaluation period. Positive correlations were found between ethylene production and As, E, stomatal conductance (gs) and root weight, while a negative correlation was recorded between days to rooting and ethylene. UV-C hastened flower production of the cuttings, but it did not affect colour parameters. We suggest that low doses of UV-C may induce endogenous ethylene production, which at low levels, interact with other hormonal mechanisms to activate root development
