Composting in well-designed systems is a better way of treating organic wastes than incineration ... more Composting in well-designed systems is a better way of treating organic wastes than incineration or landfilling (1, 2, 3). It retrieves waste materials for reuse in greenhouses or on fields in an environmentally acceptable way. The final products can be used as soil improvers or fertilisers and also to suppress plant pathogens (3, 4, 5, 6, 7, 8). The suppressive
ABSTRACT The behaviour of Fusarium oxysporum f.sp. lycopersici (Fol) and the effectiveness of the... more ABSTRACT The behaviour of Fusarium oxysporum f.sp. lycopersici (Fol) and the effectiveness of the microbial control agent Trichoderma asperellum strain T34 were examined in hydroponically grown tomato plants under five ammonium/nitrate ratios. The results showed that disease severity was reduced by the action of T34 under increasing concentrations of ammonia. Furthermore, rhizosphere F.oxysporum populations decreased with T34 application. The presence of T34 augmented leaf nitrogen concentration in treatments infested with Fol. In addition, T34 application reduced iron concentration in tomato leaves at high ammonium/nitrate ratios and reduced the severity of Fusarium wilt at high iron and nitrogen leaf concentrations.
Pepper (Capsicum annuum L.), one of the most widely grown vegetables worldwide, is susceptible to... more Pepper (Capsicum annuum L.), one of the most widely grown vegetables worldwide, is susceptible to root rot caused by Phytophthora capsici. Many biocides have recently been banned in Europe because of human health and environmental concerns. Integrated pest management is a European priority, where biological control together with other agronomic practices should replace pesticide management of plant diseases in the future. Application of different concentrations of the fungus Trichoderma asperellum strain T34 (the in T34 Biocontrol®) on incidence of disease caused by P. capsici in pepper was studied. Different methods of application of the microbial control agent and inoculation of the pathogen were examined. T34 and etridiazole (Terrazole®) were compared for their ability to suppress P. capsici. T34 reduced disease in most of the assayed situations (up to 71% disease reduction), while etridiazole was effective only when applied at the same time as the pathogen. The results obtained ...
Calli of carnation (Dianthus caryophyllus, L.) cv. Pallas resistant and susceptible to Fusarium o... more Calli of carnation (Dianthus caryophyllus, L.) cv. Pallas resistant and susceptible to Fusarium oxysporum f.sp. dianthi races 1 and 8 were exposed to fungal mycelia for 24, 48 and 72 h. The ultrastructure of the cells from carnation calli was studied by transmission electron microscopy. Fungal chitin and plant and fungal callose were detected using coloidal gold complexed to lectin wheat germ agglutinin and commercial monoclonal antibodies, (1 4 3)-β-glucan, and standard electron microscopy and cryoultramicrotomy. This study provides evidence that during the incompatible reaction, proximal and uninvaded Pallas cells delayed fungal growth with newly formed callose barriers that plugged plasmodesmata, coated cells or formed a tylose-like structure. The plant strategy induced by race 8 in Pallas was less successful with the loosening of host cell walls and the earlier penetration of the pathogen. This study showed that Pallas cells did not induce alterations in hyphal cells for either interaction. The combination of fungus-infected carnation calli and gold cytochemistry facilitates the study of race-specific early plant defense reactions.
ABSTRACT ChemInform is a weekly Abstracting Service, delivering concise information at a glance t... more ABSTRACT ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ABSTRACT Fusarium wilts are economically important diseases for which there are no effective chem... more ABSTRACT Fusarium wilts are economically important diseases for which there are no effective chemical control measures. However, biological control and fertility management are becoming efficient alternatives for controlling this disease. Growth media formulated with composts that are able to suppress Fusarium wilt of tomato provide a control system that integrates both strategies. The aim of this study was to predict Fusarium wilt suppression of growth media using abiotic and biotic variables. Grape marc compost was the most effective medium used to suppress Fusarium wilt. Cork compost was intermediate, and light peat and expanded vermiculite were the most conducive growth media. The growth media evaluated were in a pH range of 6.26 to 7.97. Both composts had high beta-glucosidase activity. When pH and beta-glucosidase activity were taken into account as predictive variables, more than 91% of the variation in severity of Fusarium wilt was explained. This relationship illustrates the effect of nutrient availability and the degree of microbiostasis, two key factors in this pathosystem. Microbial populations involved in suppressiveness were cellulolytic and oligotrophic actinomycetes, fungi, and the ratios cellulolytic actinomycetes/cellulolytic bacteria, oligotrophic bacteria/copiotrophic bacteria, and oligotrophic actinomycetes/oligotrophic bacteria. Based on community level physiological profiles, different community structures were evident among growth media evaluated.
ABSTRACT This chapter deals with the interactions established between nonpathogenic fungi/biocont... more ABSTRACT This chapter deals with the interactions established between nonpathogenic fungi/biocontrol agents and plants and their involvement in the reinforcement of plant defenses. Among the nonpathogenic fungi, one can distinguish between the true endophytic and the free-living opportunistic symbiotic fungi. As for the first group, the majority of the literature available corresponds to mycorrhizal fungi. Historically, these studies were focused on the influence of the mycorrhizal symbiosis on plant nutrition and later evolved to studies on plant immunity. Other endophytic fungi that trigger enhanced plant resistance correspond to nonpathogenic binucleate Rhizoctonia spp. and Piriformospora indica. The second group includes fungi that were considered to be free-living microorganisms that reduce plant diseases by direct competition with plant pathogens through different antagonistic mechanisms. More recently, such fungi were proven to opportunistically establish symbiotic relationships with plants and to enhance plant defense by inducing systemic resistance. The most studied genus corresponds to Trichoderma spp., but information is also available on the mode of action of nonpathogenic Fusarium oxysporum, Penicillium spp., Phoma spp., and Pythium oligandrum strains. Information about the mechanisms of action of this broad range of nonpathogenic fungi is summarized, paying special attention to the genes, proteins, and signaling pathways involved, and common patterns of defense mechanisms induced by beneficial fungi in plants are proposed.
The growth of Gardeniajasminoides Ellis plantlets and the development of photoautotrophy during t... more The growth of Gardeniajasminoides Ellis plantlets and the development of photoautotrophy during two successive culture stages (shoot multiplication and root induction) in vitro was analyzed. We examined the effects of changes in growth conditions (type of tube closure, light, and sugar levels) on the development of photoautotrophy and growth during micropropagation and sought to establish whether they affected later acclimation to conditions ex vitro. During the two stages in vitro, plantlets were grown in tubes under two different PPFD (50 and 110/zmol m -2 s -l), in media with three different sucrose concentrations (0, 1.5, and 3.0%, w/v) and with two different CO2 levels inside the tubes (controlled by either tightly closed caps or loosely sealed caps, and with an external CO2 concentration of 750 #mol tool-l). The development of photoautotrophy was assessed by determining the difference between the stable carbon isotope composition (~13C) of sugar cane sucrose used as a heterotrophic carbon source and that of leaflets grown in vitro. Plantlets from the root-induction stage showed a more highly developed photoautotrophy than those from the shoot-multiplication stage. At both stages, utilization of closed caps was the treatment which most stimulated development of photoautotrophy in plantlets. Also, lowering PPFD or sucrose concentration induced a greater degree of photoautotrophic development, the strongest effect being observed in plantlets cultured inside loosely sealed tubes. During acclimation ex vitro, plantlets taken from loosely sealed tubes in vitro performed better than those cultured inside tightly sealed tubes. The former, as well as recording a larger increase in fresh weight during this stage, also showed more negative 613C in the newly developed leaves, which would seem to indicate a better water status during acclimation. Present results validate the usefulness of ~13C analysis of leaflets as a simple technique in assessing the development of photoautotrophy during culture in vitro. In addition, ~13C analysis can be extended to evaluate growth conditions during acclimation to ex vitro conditions.
Suppressive composts are viable alternative growth media for the biological control of plant dise... more Suppressive composts are viable alternative growth media for the biological control of plant diseases. To adapt the physical properties of these composts to growth conditions, formulation is sometimes required and consequently their suppressive capacity is reduced. Green house experiments show that plant growth medium based on grape marc compost (compost:peat 1:1, v/v) amended with the biological control agent Trichoderma asperellum strain T34, restores composts' suppressive capacity against Fusarium wilt of carnation compared with the non-amended medium. Standard chemicals (tocloflos-methyl 50% and captan 85%) used in the cultivation of carnation crops did not improve the suppressive capacity of the growth media or the T34 populations. However, they impaired the stomatal conductance of plants and increased the populations of the pathogen (interaction chemical and T34). Water use measurements of carnation plants, namely stomatal conductance, transpiration and daily water uptake, correlated negatively with Fusarium wilt disease. Plants in T34-amended growth media had higher water demand, regardless of the treatment, which implied their growth could be enhanced by increasing fertirrigation, compared to plants non-amended with T34. In conclusion, the amendment of formulated grape marc compost with T. asperellum T34 improves the suppressive capacity of this growth medium against Fusarium wilt in carnation. It is a better alternative for plant and disease control than the standard chemicals used.
Using composts in agriculture to minimize organic wastes and to reduce the addition of fertilizer... more Using composts in agriculture to minimize organic wastes and to reduce the addition of fertilizers and fungicides in crop production is highly eVective. Our results show that among those tested composts aged 0.5-1 year, cork compost reduced diseases caused by Rhizoctonia solani in cucumber plants (53% of diseased plants) in comparison to peat (up to 89%). However, all composts aged 1.5-3 years (comprised of cork, grape marc, olive marc and spent mushroom) highly suppressed Rhizoctonia disease, measuring 3, 11, 27 and 29% of diseased plants, respectively. Plant growth media enriched with the biological control agent Trichoderma asperellum (strain T-34) reduced the incidence of R. solani disease when amended at 10 3 cfu ml ¡1 . In composts aged 0.5-1 year, T-34 was only eYcient when added to spent mushroom and cork compost, although it remained well established in all of them. The fact that T-34 rendered all composts aged 1.5-3 years highly suppressive is attributed to the low levels of easily biodegradable substances. Rhizoctonia damping-oV in cucumber plants can be reduced by using composts and/or the biological control agent T. asperellum strain T-34. In addition, the extent to which composts suppress this disease depends on the nature of the composted materials, increasing with the composts' maturity level. (M.I. Trillas).
ABSTRACT Carnation plantlets (Dianthus caryophyllus L.) cultured in vitro often develop morpholog... more ABSTRACT Carnation plantlets (Dianthus caryophyllus L.) cultured in vitro often develop morphological and physiological anomalies, a phenomenon called hyperhydricity, which impairs their survival ex vitro. When the agar concentration of the growth medium was increased (from 0 to 12 g dm−3), thereby reducing water availability, the hyperhydricity of those adventitious shoots regenerated from carnation petals decreased. This was accompanied by a progressive fall in the water content of shoots (94.9 to 91.4 %), fresh mass (from 57.2 to 1.8 mg), number of leaf parenchyma cell layers (from 9.3 to 7.7), and the size of these cells (from 968 to 254 µm2). However, the number of regenerated shoots also decreased (17.7 in 2 g dm−3 agar to 4.3 in 12 g dm−3). Similarly, in ventilated tubes, which exhibit a lower relative humidity than tightly closed tubes, shoot organogenesis diminished up to 28 %, in tandem with shoot water content. Thus, relative humidity and water availability in culture vessels do not only influence shoot hyperhydricity in carnations, but also greatly affect adventitious shoot organogenesis.
Two biological control practices are the use of suppressive growing media and the application of ... more Two biological control practices are the use of suppressive growing media and the application of biological control agents (BCAs). The goals of this study were: (i) to screen 584 potential BCAs obtained from Fusarium wilt (FW) suppressive growing media; (ii) to evaluate in greenhouse conditions selected BCAs in three growing media with different degrees of suppressiveness of tomato FW. Two isolates selected after screening were identified as Fusarium solani (305) and Streptomyces sp. (A19). Results showed that tomato FW was reduced and total production was improved when both BCAs were applied to a conducive medium (coir fiber). In highly suppressive growing medium (grape marc compost), A19 and 305 inoculations did not improve suppressiveness. In moderately suppressive growing medium (cork compost), only A19 improved this compost to natural grape marc compost suppressiveness level. Therefore, compost suppressiveness of tomato FW depended on the nature of the compost and on the isolates applied.
The study of the heterogeneous photocatalytlc oxldatlon of phenoxyacetlc acid m presence of near-... more The study of the heterogeneous photocatalytlc oxldatlon of phenoxyacetlc acid m presence of near-W flummated T102 us cemed out The Lxngmmr-Hmshelwo4 kmetwa model fita the expenmental data of phenoxyacetlc dwppeerance, and reaction rate and eqmhbrmm adsorptlon constants are reported The effect of temperature, pH, mtenslty of mcldent hght and mane of catalyst on the reaction rate IS ascertamed Some mtermeduste producta are detected and carbon &ox& wan found to be the final product of the reaction
Samples of iron-doped titania prepared by the wet impregnation method from TiO 2 (Degussa P-25) a... more Samples of iron-doped titania prepared by the wet impregnation method from TiO 2 (Degussa P-25) and two different precursors, Fe(NO 3 ) 3 .9H 2 O and Fe(III) acetylacetonate, were tested as photocatalysts in two reactions: nitrite oxidation and Cr(VI) reduction at pH 6.5. Whereas samples prepared from Fe(NO 3 ) 3 .9H 2 O containing low amounts of iron (less than 2 wt.%) were more ef®cient for nitrite oxidation than pure TiO 2 , specimens obtained from Fe(III) acetylacetonate were less active. In the case of Cr(VI) reduction, all doped samples were less active than TiO 2 with no sensibly differential activity. Different mechanistic pathways and structural and surface properties of the samples are invoked to explain the observed behavior. # 1998 Elsevier Science B.V.
Composting in well-designed systems is a better way of treating organic wastes than incineration ... more Composting in well-designed systems is a better way of treating organic wastes than incineration or landfilling (1, 2, 3). It retrieves waste materials for reuse in greenhouses or on fields in an environmentally acceptable way. The final products can be used as soil improvers or fertilisers and also to suppress plant pathogens (3, 4, 5, 6, 7, 8). The suppressive
ABSTRACT The behaviour of Fusarium oxysporum f.sp. lycopersici (Fol) and the effectiveness of the... more ABSTRACT The behaviour of Fusarium oxysporum f.sp. lycopersici (Fol) and the effectiveness of the microbial control agent Trichoderma asperellum strain T34 were examined in hydroponically grown tomato plants under five ammonium/nitrate ratios. The results showed that disease severity was reduced by the action of T34 under increasing concentrations of ammonia. Furthermore, rhizosphere F.oxysporum populations decreased with T34 application. The presence of T34 augmented leaf nitrogen concentration in treatments infested with Fol. In addition, T34 application reduced iron concentration in tomato leaves at high ammonium/nitrate ratios and reduced the severity of Fusarium wilt at high iron and nitrogen leaf concentrations.
Pepper (Capsicum annuum L.), one of the most widely grown vegetables worldwide, is susceptible to... more Pepper (Capsicum annuum L.), one of the most widely grown vegetables worldwide, is susceptible to root rot caused by Phytophthora capsici. Many biocides have recently been banned in Europe because of human health and environmental concerns. Integrated pest management is a European priority, where biological control together with other agronomic practices should replace pesticide management of plant diseases in the future. Application of different concentrations of the fungus Trichoderma asperellum strain T34 (the in T34 Biocontrol®) on incidence of disease caused by P. capsici in pepper was studied. Different methods of application of the microbial control agent and inoculation of the pathogen were examined. T34 and etridiazole (Terrazole®) were compared for their ability to suppress P. capsici. T34 reduced disease in most of the assayed situations (up to 71% disease reduction), while etridiazole was effective only when applied at the same time as the pathogen. The results obtained ...
Calli of carnation (Dianthus caryophyllus, L.) cv. Pallas resistant and susceptible to Fusarium o... more Calli of carnation (Dianthus caryophyllus, L.) cv. Pallas resistant and susceptible to Fusarium oxysporum f.sp. dianthi races 1 and 8 were exposed to fungal mycelia for 24, 48 and 72 h. The ultrastructure of the cells from carnation calli was studied by transmission electron microscopy. Fungal chitin and plant and fungal callose were detected using coloidal gold complexed to lectin wheat germ agglutinin and commercial monoclonal antibodies, (1 4 3)-β-glucan, and standard electron microscopy and cryoultramicrotomy. This study provides evidence that during the incompatible reaction, proximal and uninvaded Pallas cells delayed fungal growth with newly formed callose barriers that plugged plasmodesmata, coated cells or formed a tylose-like structure. The plant strategy induced by race 8 in Pallas was less successful with the loosening of host cell walls and the earlier penetration of the pathogen. This study showed that Pallas cells did not induce alterations in hyphal cells for either interaction. The combination of fungus-infected carnation calli and gold cytochemistry facilitates the study of race-specific early plant defense reactions.
ABSTRACT ChemInform is a weekly Abstracting Service, delivering concise information at a glance t... more ABSTRACT ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ABSTRACT Fusarium wilts are economically important diseases for which there are no effective chem... more ABSTRACT Fusarium wilts are economically important diseases for which there are no effective chemical control measures. However, biological control and fertility management are becoming efficient alternatives for controlling this disease. Growth media formulated with composts that are able to suppress Fusarium wilt of tomato provide a control system that integrates both strategies. The aim of this study was to predict Fusarium wilt suppression of growth media using abiotic and biotic variables. Grape marc compost was the most effective medium used to suppress Fusarium wilt. Cork compost was intermediate, and light peat and expanded vermiculite were the most conducive growth media. The growth media evaluated were in a pH range of 6.26 to 7.97. Both composts had high beta-glucosidase activity. When pH and beta-glucosidase activity were taken into account as predictive variables, more than 91% of the variation in severity of Fusarium wilt was explained. This relationship illustrates the effect of nutrient availability and the degree of microbiostasis, two key factors in this pathosystem. Microbial populations involved in suppressiveness were cellulolytic and oligotrophic actinomycetes, fungi, and the ratios cellulolytic actinomycetes/cellulolytic bacteria, oligotrophic bacteria/copiotrophic bacteria, and oligotrophic actinomycetes/oligotrophic bacteria. Based on community level physiological profiles, different community structures were evident among growth media evaluated.
ABSTRACT This chapter deals with the interactions established between nonpathogenic fungi/biocont... more ABSTRACT This chapter deals with the interactions established between nonpathogenic fungi/biocontrol agents and plants and their involvement in the reinforcement of plant defenses. Among the nonpathogenic fungi, one can distinguish between the true endophytic and the free-living opportunistic symbiotic fungi. As for the first group, the majority of the literature available corresponds to mycorrhizal fungi. Historically, these studies were focused on the influence of the mycorrhizal symbiosis on plant nutrition and later evolved to studies on plant immunity. Other endophytic fungi that trigger enhanced plant resistance correspond to nonpathogenic binucleate Rhizoctonia spp. and Piriformospora indica. The second group includes fungi that were considered to be free-living microorganisms that reduce plant diseases by direct competition with plant pathogens through different antagonistic mechanisms. More recently, such fungi were proven to opportunistically establish symbiotic relationships with plants and to enhance plant defense by inducing systemic resistance. The most studied genus corresponds to Trichoderma spp., but information is also available on the mode of action of nonpathogenic Fusarium oxysporum, Penicillium spp., Phoma spp., and Pythium oligandrum strains. Information about the mechanisms of action of this broad range of nonpathogenic fungi is summarized, paying special attention to the genes, proteins, and signaling pathways involved, and common patterns of defense mechanisms induced by beneficial fungi in plants are proposed.
The growth of Gardeniajasminoides Ellis plantlets and the development of photoautotrophy during t... more The growth of Gardeniajasminoides Ellis plantlets and the development of photoautotrophy during two successive culture stages (shoot multiplication and root induction) in vitro was analyzed. We examined the effects of changes in growth conditions (type of tube closure, light, and sugar levels) on the development of photoautotrophy and growth during micropropagation and sought to establish whether they affected later acclimation to conditions ex vitro. During the two stages in vitro, plantlets were grown in tubes under two different PPFD (50 and 110/zmol m -2 s -l), in media with three different sucrose concentrations (0, 1.5, and 3.0%, w/v) and with two different CO2 levels inside the tubes (controlled by either tightly closed caps or loosely sealed caps, and with an external CO2 concentration of 750 #mol tool-l). The development of photoautotrophy was assessed by determining the difference between the stable carbon isotope composition (~13C) of sugar cane sucrose used as a heterotrophic carbon source and that of leaflets grown in vitro. Plantlets from the root-induction stage showed a more highly developed photoautotrophy than those from the shoot-multiplication stage. At both stages, utilization of closed caps was the treatment which most stimulated development of photoautotrophy in plantlets. Also, lowering PPFD or sucrose concentration induced a greater degree of photoautotrophic development, the strongest effect being observed in plantlets cultured inside loosely sealed tubes. During acclimation ex vitro, plantlets taken from loosely sealed tubes in vitro performed better than those cultured inside tightly sealed tubes. The former, as well as recording a larger increase in fresh weight during this stage, also showed more negative 613C in the newly developed leaves, which would seem to indicate a better water status during acclimation. Present results validate the usefulness of ~13C analysis of leaflets as a simple technique in assessing the development of photoautotrophy during culture in vitro. In addition, ~13C analysis can be extended to evaluate growth conditions during acclimation to ex vitro conditions.
Suppressive composts are viable alternative growth media for the biological control of plant dise... more Suppressive composts are viable alternative growth media for the biological control of plant diseases. To adapt the physical properties of these composts to growth conditions, formulation is sometimes required and consequently their suppressive capacity is reduced. Green house experiments show that plant growth medium based on grape marc compost (compost:peat 1:1, v/v) amended with the biological control agent Trichoderma asperellum strain T34, restores composts' suppressive capacity against Fusarium wilt of carnation compared with the non-amended medium. Standard chemicals (tocloflos-methyl 50% and captan 85%) used in the cultivation of carnation crops did not improve the suppressive capacity of the growth media or the T34 populations. However, they impaired the stomatal conductance of plants and increased the populations of the pathogen (interaction chemical and T34). Water use measurements of carnation plants, namely stomatal conductance, transpiration and daily water uptake, correlated negatively with Fusarium wilt disease. Plants in T34-amended growth media had higher water demand, regardless of the treatment, which implied their growth could be enhanced by increasing fertirrigation, compared to plants non-amended with T34. In conclusion, the amendment of formulated grape marc compost with T. asperellum T34 improves the suppressive capacity of this growth medium against Fusarium wilt in carnation. It is a better alternative for plant and disease control than the standard chemicals used.
Using composts in agriculture to minimize organic wastes and to reduce the addition of fertilizer... more Using composts in agriculture to minimize organic wastes and to reduce the addition of fertilizers and fungicides in crop production is highly eVective. Our results show that among those tested composts aged 0.5-1 year, cork compost reduced diseases caused by Rhizoctonia solani in cucumber plants (53% of diseased plants) in comparison to peat (up to 89%). However, all composts aged 1.5-3 years (comprised of cork, grape marc, olive marc and spent mushroom) highly suppressed Rhizoctonia disease, measuring 3, 11, 27 and 29% of diseased plants, respectively. Plant growth media enriched with the biological control agent Trichoderma asperellum (strain T-34) reduced the incidence of R. solani disease when amended at 10 3 cfu ml ¡1 . In composts aged 0.5-1 year, T-34 was only eYcient when added to spent mushroom and cork compost, although it remained well established in all of them. The fact that T-34 rendered all composts aged 1.5-3 years highly suppressive is attributed to the low levels of easily biodegradable substances. Rhizoctonia damping-oV in cucumber plants can be reduced by using composts and/or the biological control agent T. asperellum strain T-34. In addition, the extent to which composts suppress this disease depends on the nature of the composted materials, increasing with the composts' maturity level. (M.I. Trillas).
ABSTRACT Carnation plantlets (Dianthus caryophyllus L.) cultured in vitro often develop morpholog... more ABSTRACT Carnation plantlets (Dianthus caryophyllus L.) cultured in vitro often develop morphological and physiological anomalies, a phenomenon called hyperhydricity, which impairs their survival ex vitro. When the agar concentration of the growth medium was increased (from 0 to 12 g dm−3), thereby reducing water availability, the hyperhydricity of those adventitious shoots regenerated from carnation petals decreased. This was accompanied by a progressive fall in the water content of shoots (94.9 to 91.4 %), fresh mass (from 57.2 to 1.8 mg), number of leaf parenchyma cell layers (from 9.3 to 7.7), and the size of these cells (from 968 to 254 µm2). However, the number of regenerated shoots also decreased (17.7 in 2 g dm−3 agar to 4.3 in 12 g dm−3). Similarly, in ventilated tubes, which exhibit a lower relative humidity than tightly closed tubes, shoot organogenesis diminished up to 28 %, in tandem with shoot water content. Thus, relative humidity and water availability in culture vessels do not only influence shoot hyperhydricity in carnations, but also greatly affect adventitious shoot organogenesis.
Two biological control practices are the use of suppressive growing media and the application of ... more Two biological control practices are the use of suppressive growing media and the application of biological control agents (BCAs). The goals of this study were: (i) to screen 584 potential BCAs obtained from Fusarium wilt (FW) suppressive growing media; (ii) to evaluate in greenhouse conditions selected BCAs in three growing media with different degrees of suppressiveness of tomato FW. Two isolates selected after screening were identified as Fusarium solani (305) and Streptomyces sp. (A19). Results showed that tomato FW was reduced and total production was improved when both BCAs were applied to a conducive medium (coir fiber). In highly suppressive growing medium (grape marc compost), A19 and 305 inoculations did not improve suppressiveness. In moderately suppressive growing medium (cork compost), only A19 improved this compost to natural grape marc compost suppressiveness level. Therefore, compost suppressiveness of tomato FW depended on the nature of the compost and on the isolates applied.
The study of the heterogeneous photocatalytlc oxldatlon of phenoxyacetlc acid m presence of near-... more The study of the heterogeneous photocatalytlc oxldatlon of phenoxyacetlc acid m presence of near-W flummated T102 us cemed out The Lxngmmr-Hmshelwo4 kmetwa model fita the expenmental data of phenoxyacetlc dwppeerance, and reaction rate and eqmhbrmm adsorptlon constants are reported The effect of temperature, pH, mtenslty of mcldent hght and mane of catalyst on the reaction rate IS ascertamed Some mtermeduste producta are detected and carbon &ox& wan found to be the final product of the reaction
Samples of iron-doped titania prepared by the wet impregnation method from TiO 2 (Degussa P-25) a... more Samples of iron-doped titania prepared by the wet impregnation method from TiO 2 (Degussa P-25) and two different precursors, Fe(NO 3 ) 3 .9H 2 O and Fe(III) acetylacetonate, were tested as photocatalysts in two reactions: nitrite oxidation and Cr(VI) reduction at pH 6.5. Whereas samples prepared from Fe(NO 3 ) 3 .9H 2 O containing low amounts of iron (less than 2 wt.%) were more ef®cient for nitrite oxidation than pure TiO 2 , specimens obtained from Fe(III) acetylacetonate were less active. In the case of Cr(VI) reduction, all doped samples were less active than TiO 2 with no sensibly differential activity. Different mechanistic pathways and structural and surface properties of the samples are invoked to explain the observed behavior. # 1998 Elsevier Science B.V.
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Papers by M. Trillas