Maintaining postharvest quality of the tomato fruit by employing methyl jasmonate and ethanol vapor treatment

The postharvest quality of tomato fruit (Lycopersicon esculentum L.) was evaluated after treatment with natural volatile compounds (methyl jasmonate [MJ] or ethanol) and storage at 13C during or following vapor exposure. The fruit treated with natural volatiles did not differ on fruit decay during vapor exposure, but following exposure and transfer to ambient air, the fruit had less decay at storage temperature. Volatile-treated fruit tended to maintain firmness during exposure, and the effects were significant for ethanol-treated fruit, following storage to ambient air. Sugar (i.e., fructose and glucose) concentration was stimulated in ethanol-treated fruit following exposure and transfer to ambient air. Ascorbic acid concentration was stimulated in MJ-treated fruit during exposure and persisted (including ethanol treatment) following transfer to ambient air. Total phenolics declined during vapor exposure and increased for MJ-treated fruit after transfer to ambient air. Lycopene concentration did not differ during MJ exposure but increased following volatile exposure. The fruit samples treated with vapors had accelerated percentage weight loss compared with untreated fruit during ripening but without commercial interest, whereas citric acid content did not differ among the treatments. The results suggest that MJ and ethanol vapor may improve fruit quality-related attributes on top of the well-documented antimicrobial protection during fresh produce storage and transit. The data presented in this work suggest that the use of natural volatiles is an innovative and useful tool as an alternative to the use of synthetic fungicides or other sanitation techniques in storage/packaging. Vapor enrichment may reduce disease development with a major contribution to limiting the spread of the pathogen by lowering the spore load (spore production) in the storage/transit atmospheres as well as the use of natural volatiles as an alternative food preservative. In addition to these, the improvement of fruit quality observed in the present work is of great market importance. The effects of natural compounds on individual microorganisms (fungi and bacteria), both responsible for spoilage and foodborne pathogens, as well as the minimum concentration to gain effectiveness without affecting fresh produce quality and storage deserve further research. © 2007, Blackwell Publishing

Shredded maize stems as an alternative substrate medium

There is increased interest in the use of mixes of inorganic and organic materials as substrates in soilless culture in greenhouses, especially in parts of the world where the mixtures have not been commonly used. The potential of different ratios of shredded maize (Zea mays L.) stems as organic media on nutrient uptake, and the performance of tomato (Lycopersicon esculentum Mill.), in soilless culture, were studied. Tomato plants, cv. Belladona, were grown over a five-month period in a closed soilless culture system on four different substrates (pumice alone, shredded maize stems alone, pumice mixed with 25% or 50% maize shredded stems) and in Nutrient Film Technique, in an un-heated glasshouse. The amount of nutrient solution absorbed increased in proportion to days following transplanting, and was in part dependent on the strength of radiation and night temperature after the middle stage of growth. Plants grown on pumice + 50% maize and maize alone had similar distributions of elemental nutrient uptake. Elemental content in fruit was different only for Mn, Cu, B and Na among substrates. The ratio of number of leaves/fruit produced, favored plants grown in pumice + 50% maize, but plants grown in maize produced the greater number of fruit and the least number of leaves. No regression was observed between numbers of fruit and mean fruit weight. As nutrient uptake increased so did water uptake, with plants grown on pumice having the greater water use efficiency. The addition of maize in different ratios (25-50%) in pumice may improve its properties as a substrate for tomato soilless culture. The ratio of 50% shredded maize stems mixed with pumice could be the optimum mix for protected tomato production under the prevailing local conditions

Maintaining postharvest quality of the tomato fruit by employing methyl jasmonate and ethanol vapor treatment

The postharvest quality of tomato fruit (Lycopersicon esculentum L.) was evaluated after treatment with natural volatile compounds (methyl jasmonate [MJ] or ethanol) and storage at 13C during or following vapor exposure. The fruit treated with natural volatiles did not differ on fruit decay during vapor exposure, but following exposure and transfer to ambient air, the fruit had less decay at storage temperature. Volatile-treated fruit tended to maintain firmness during exposure, and the effects were significant for ethanol-treated fruit, following storage to ambient air. Sugar (i.e., fructose and glucose) concentration was stimulated in ethanol-treated fruit following exposure and transfer to ambient air. Ascorbic acid concentration was stimulated in MJ-treated fruit during exposure and persisted (including ethanol treatment) following transfer to ambient air. Total phenolics declined during vapor exposure and increased for MJ-treated fruit after transfer to ambient air. Lycopene concentration did not differ during MJ exposure but increased following volatile exposure. The fruit samples treated with vapors had accelerated percentage weight loss compared with untreated fruit during ripening but without commercial interest, whereas citric acid content did not differ among the treatments. The results suggest that MJ and ethanol vapor may improve fruit quality-related attributes on top of the well-documented antimicrobial protection during fresh produce storage and transit. The data presented in this work suggest that the use of natural volatiles is an innovative and useful tool as an alternative to the use of synthetic fungicides or other sanitation techniques in storage/packaging. Vapor enrichment may reduce disease development with a major contribution to limiting the spread of the pathogen by lowering the spore load (spore production) in the storage/transit atmospheres as well as the use of natural volatiles as an alternative food preservative. In addition to these, the improvement of fruit quality observed in the present work is of great market importance. The effects of natural compounds on individual microorganisms (fungi and bacteria), both responsible for spoilage and foodborne pathogens, as well as the minimum concentration to gain effectiveness without affecting fresh produce quality and storage deserve further research. © 2007, Blackwell Publishing

Antifungal activity of lemongrass (Cympopogon citratus L.) essential oil against key postharvest pathogens

Lemongrass (Cympopogon citratus L.) oil (ranging between 25 and 500 ppm) was tested for antifungal activity against Colletotrichum coccodes, Botrytis cinerea, Cladosporium herbarum, Rhizopus stolonifer and Aspergillus niger in vitro. Oil-enrichment resulted in significant (P < 0.05) reduction on subsequent colony development for the examined pathogens. Fungal spore production inhibited up to 70% at 25 ppm of lemongrass oil concentration when compared with equivalent plates stored in ambient air. In the highest oil concentration (500 ppm) employed, fungal sporulation was completely retarded. Lemongrass oil reduced spore germination and germ tube length in C. coccodes, B. cinerea, C. herbarum and R. stolonifer with the effects dependent on oil concentration. However, lemongrass oil (up to 100 ppm) accelerated spore germination for A. niger. Work is currently focussing on the mechanisms underlying the impacts of essential oil volatiles on disease development with a major contribution to limiting the spread of the pathogen by lowering the spore load in the storage/transit atmospheres as well as the use of essential oil as an alternative food preservative. Industrial relevance: The present study suggests that the use of pure lemongrass essential oil is an innovative and useful tool as alternative to the use of synthetic fungicides or other sanitation techniques in storage/packaging. Oil enrichment may reduce disease development with a major contribution to limiting the spread of the pathogen by lowering the spore load (spore production) in the storage/transit atmospheres as well as the use of essential oil as an alternative food preservative. The effectiveness (oil concentration) of the oil depends on the target pathogen. The effects of natural compounds on individual microorganisms (fungi and bacteria), both responsible for spoilage and food-borne pathogens, as well as the minimum concentration to gain effectiveness without affecting fresh produce quality and storage deserve further research. © 2007 Elsevier Ltd. All rights reserved

Antifungal activity of lemongrass (Cympopogon citratus L.) essential oil against key postharvest pathogens

Lemongrass (Cympopogon citratus L.) oil (ranging between 25 and 500 ppm) was tested for antifungal activity against Colletotrichum coccodes, Botrytis cinerea, Cladosporium herbarum, Rhizopus stolonifer and Aspergillus niger in vitro. Oil-enrichment resulted in significant (P < 0.05) reduction on subsequent colony development for the examined pathogens. Fungal spore production inhibited up to 70% at 25 ppm of lemongrass oil concentration when compared with equivalent plates stored in ambient air. In the highest oil concentration (500 ppm) employed, fungal sporulation was completely retarded. Lemongrass oil reduced spore germination and germ tube length in C. coccodes, B. cinerea, C. herbarum and R. stolonifer with the effects dependent on oil concentration. However, lemongrass oil (up to 100 ppm) accelerated spore germination for A. niger. Work is currently focussing on the mechanisms underlying the impacts of essential oil volatiles on disease development with a major contribution to limiting the spread of the pathogen by lowering the spore load in the storage/transit atmospheres as well as the use of essential oil as an alternative food preservative. Industrial relevance: The present study suggests that the use of pure lemongrass essential oil is an innovative and useful tool as alternative to the use of synthetic fungicides or other sanitation techniques in storage/packaging. Oil enrichment may reduce disease development with a major contribution to limiting the spread of the pathogen by lowering the spore load (spore production) in the storage/transit atmospheres as well as the use of essential oil as an alternative food preservative. The effectiveness (oil concentration) of the oil depends on the target pathogen. The effects of natural compounds on individual microorganisms (fungi and bacteria), both responsible for spoilage and food-borne pathogens, as well as the minimum concentration to gain effectiveness without affecting fresh produce quality and storage deserve further research. © 2007 Elsevier Ltd. All rights reserved

Shredded maize stems as an alternative substrate medium

There is increased interest in the use of mixes of inorganic and organic materials as substrates in soilless culture in greenhouses, especially in parts of the world where the mixtures have not been commonly used. The potential of different ratios of shredded maize (Zea mays L.) stems as organic media on nutrient uptake, and the performance of tomato (Lycopersicon esculentum Mill.), in soilless culture, were studied. Tomato plants, cv. Belladona, were grown over a five-month period in a closed soilless culture system on four different substrates (pumice alone, shredded maize stems alone, pumice mixed with 25% or 50% maize shredded stems) and in Nutrient Film Technique, in an un-heated glasshouse. The amount of nutrient solution absorbed increased in proportion to days following transplanting, and was in part dependent on the strength of radiation and night temperature after the middle stage of growth. Plants grown on pumice + 50% maize and maize alone had similar distributions of elemental nutrient uptake. Elemental content in fruit was different only for Mn, Cu, B and Na among substrates. The ratio of number of leaves/fruit produced, favored plants grown in pumice + 50% maize, but plants grown in maize produced the greater number of fruit and the least number of leaves. No regression was observed between numbers of fruit and mean fruit weight. As nutrient uptake increased so did water uptake, with plants grown on pumice having the greater water use efficiency. The addition of maize in different ratios (25-50%) in pumice may improve its properties as a substrate for tomato soilless culture. The ratio of 50% shredded maize stems mixed with pumice could be the optimum mix for protected tomato production under the prevailing local conditions

Life cycle assessment for the determination of key environmental impact indicators in soilless tomato culture and mitigation potential

The interest in the use of mixtures of inorganic and organic materials as substrate media in soilless culture in greenhouses is increasing in parts of the world where the mixtures have not been used in common practice. Material efficacy can affect the plant yield, water and fertilizer use efficiency, energy consumption, and final cost for the production of 1 kg of produce. In this study, tomato plants (Solanum lycopersicum 'Belladona') were grown over five months in a closed soilless culture system on seven different substrates (perlite or pumice and their mixtures with 25 or 50% shredded maize stems) in an unheated greenhouse. Life cycle assessment was applied to assess the impact of the production system on the environment. As key performance indicators, the carbon footprint, the water footprint and energy efficiency were determined for the seven different substrates. The system boundaries were from cradle to farm gate. Comparisons of the indicators to greenhouse and field tomato production were made as well as suggestions to mitigate the impact of this production method on the environment

Life cycle assessment for the determination of key environmental impact indicators in soilless tomato culture and mitigation potential

The interest in the use of mixtures of inorganic and organic materials as substrate media in soilless culture in greenhouses is increasing in parts of the world where the mixtures have not been used in common practice. Material efficacy can affect the plant yield, water and fertilizer use efficiency, energy consumption, and final cost for the production of 1 kg of produce. In this study, tomato plants (Solanum lycopersicum 'Belladona') were grown over five months in a closed soilless culture system on seven different substrates (perlite or pumice and their mixtures with 25 or 50% shredded maize stems) in an unheated greenhouse. Life cycle assessment was applied to assess the impact of the production system on the environment. As key performance indicators, the carbon footprint, the water footprint and energy efficiency were determined for the seven different substrates. The system boundaries were from cradle to farm gate. Comparisons of the indicators to greenhouse and field tomato production were made as well as suggestions to mitigate the impact of this production method on the environment

Transcriptome analysis approaches for the isolation of trichome-specific genes from the medicinal plant Cistus creticus subsp. creticus

Cistus creticus subsp. creticus is a plant of intrinsic scientific interest due to the distinctive pharmaceutical properties of its resin. Labdane-type diterpenes, the main constituents of the resin, exhibit considerable antibacterial and cytotoxic activities. In this study chemical analysis of isolated trichomes from different developmental stages revealed that young leaves of 1–2 cm length displayed the highest content of labdane-type diterpenes (80 mg/g fresh weight) whereas trichomes from older leaves (2–3 or 3–4 cm) exhibited gradual decreased concentrations. A cDNA library was constructed enriched in transcripts from trichomes isolated from young leaves, which are characterized by high levels of labdane-type diterpenes. Functional annotation of 2,022 expressed sequence tags (ESTs) from the trichome cDNA library based on homology to A. thaliana genes suggested that 8% of the putative identified sequences were secondary metabolism-related and involved primarily in flavonoid and terpenoid biosynthesis. A significant proportion of the ESTs (38%) displayed no significant similarity to any other DNA deposited in databases, indicating a yet unknown function. Custom DNA microarrays constructed with 1,248 individual clones from the cDNA library facilitated transcriptome comparisons between trichomes and trichome-free tissues. In addition, gene expression studies in various Cistus tissues and organs for one of the genes highlighted as the most differentially expressed by the microarray experiments revealed a putative sesquiterpene synthase with a trichome-specific expression pattern. Full length cDNA isolation and heterologous expression in E. coli followed by biochemical analysis, led to the characterization of the produced protein as germacrene B synthase