What is the optimal fertigation start time and frequency in lettuce seedlings?

Although lettuce is one of the most important vegetable crops cultivated in Brazil, producers conduct seedling production empirically, as there are no published reports on the optimal start time and management strategy for seedling fertigation. The present aimed to assess the influence of fertigation management on the growth, physiological aspects and nutritional status of lettuce seedlings and to determine the optimal fertigation start time and frequency. Two experiments were conducted, each with a randomized block design and six repetitions. The first consisted of six treatments, namely six fertigation start times at 0, 3, 6, 9, 12, and 15 d after emergence (DAE), and the second consisted of five treatments, representing different application frequencies at 3, 4, 5, 6, and 7 d intervals. The assessment of nutrient accumulation levels and biometric and physiological characteristics of the seedlings were performed after transplanting. Fertigation start times significantly affected 14 of the 18 variables assessed, particularly the number of leaves, shoot dry weight, leaf area, initial chlorophyll fluorescence, and P, K, Ca, Mg, and S accumulation. The best results for ten variables were obtained when fertigation began at emergence, with values 17.77 - 35.63% higher than those at fertigation onset at 15 DAE. Application frequency only influenced chlorophyll content and N, P, K, and S accumulation, with optimal results obtained at 3 - 6 d intervals. Beginning fertigation at plant emergence favors dry weight production, nutrition and photosynthesis and shortens the production time of lettuce seedlings. The optimal start time for lettuce seedling fertigation is at emergence, with application performed every 6 d.

Potential of rhizobacteria native to Argentina for the control of Meloidogyne javanica / Potencial de rizobacterias nativas de Argentina para el control de Meloidogyne javanica

Abstract Biocontrol of the nematode Meloidogyne javanica was studied using the Argentinean strains Pseudomonas fluorescens MME3, TAE4, TAR5 and ZME4 and Bacillus sp. B7S, B9T and B19S. Pseudomonas protegens CHA0 was used as a positive control. Egg hatching and juvenile mortality were evaluated in vitro by exposure of nematodes to bacterial suspensions or their cell-free supernatants (CFS). The effect of bacteria on nematode infestation of lettuce was also studied. results showed that most of the tested strains and CFS reduced egg hatching and juvenile survival in vitro. The bacterial suspension of Bacillus sp. B9T produced the lowest hatching of eggs. Juvenile mortality was higher when M. javanica was exposed to Bacillus sp. than to Pseudomonas spp. suspensions. Except for CFS of B9T, all filtrates inhibited hatching at levels similar to or higher than the biocontrol strain P. protegens CHA0. The CFS of CHA0 showed the highest level of juvenile mortality followed by Bacillus sp. strains and P. fluorescens TAE4. None of the inoculated rhizobacteria reverted the negative effect of infestation on the aerial dry weight of lettuce plants. However, inoculation impacted on reproduction of M. javanica by reducing the development of galls and egg masses on roots and diminishing the number of individuals both on roots and in the substrate, as well as the reproduction factor. These results show that most of the analyzed native strains can control the nematode M. javanica. Among them, P. fluorescens TAE4 and Bacillus sp. B9T showed the most promising performances for the biocontrol of this pathogen and have a potential use in the formulation of commercial products.

Resumen Se estudiaron las cepas argentinas Pseudomonas fluorescens MME3, TAE4, TAR5 y ZME4 y Bacillus sp. B7S, B9T y B19S para el control del nematodo Meloidogyne javanica. Pseudomonas protegens CHA0 se utilizó como control positivo. La eclosión de huevos y la mortalidad de juveniles se evaluaron in vitro al exponerlos a suspensiones bacterianas y a sus sobrenadantes libres de células (SLC). Asimismo, se estudió la inoculación bacteriana sobre la infestación del nematodo en lechuga. Los resultados in vitro indicaron que la mayoría de las cepas, así como sus SLC redujeron la eclosión y la supervivencia de M. javanica. La suspensión de Bacillus sp. B9T produjo los menores niveles de eclosión. La mortalidad de juveniles fue mayor al exponerlos a suspensiones de Bacillus sp. respecto de Pseudomonas spp. Los SLC inhibieron la eclosión de huevos en niveles similares o superiores a P. protegens CHA0, excepto por el de B9T. La exposición a SLC de CHA0 registró la mayor mortalidad, seguido por las cepas de Bacillus sp. y P. fluorescens TAE4. La inoculación bacteriana no revertió el efecto de la infestación sobre el peso seco aéreo de las plantas, sin embargo, afectó la multiplicación de M. javanica lo que redujo el desarrollo de agallas y las masas de huevos, y disminuyó el número de individuos presentes tanto en la raíz como en el sustrato, así como el factor de reproducción. Los resultados indican que la mayoría de las cepas nativas evaluadas son capaces de controlar a M. javanica. Entre ellas, P. fluorescens TAE4 y Bacillus sp. B9T, se presentan como las más promisorias para el control de este patógeno, con potencialidad para ser utilizadas en la formulación de productos biológicos.

Contribution of the carbonized rice husk added to the substrate in the production of vegetable seedlings

The carbonized rice husk (CRH) is an agro-industrial residue with great potential for use in mixtures with other substrates for the production of vegetable seedlings. Thus, the purpose of this study was to evaluate the effect of the addition of CRH to the commercial substrate for the production of greenhouse seedlings. The evaluated vegetables were lettuce, broccoli and mustard, cultivated in polystyrene foam (Styrofoam®) trays. Five treatments were evaluated: 100% of the commercial substrate (CS); 25% of CRH + 75% of CS; 50% of CRH + 50% of CS; 75% CRH + 25% CS; and 100% CRH, in a completely randomized design with twelve replicates. The substrates were evaluated for their physical and chemical characteristics. The morphometric evaluations were: number of leaves per plant, plant height, shoot fresh matter yield, root length, and shoot and root dry matter yield. The data were submitted to regression analysis, and the homogeneity of the variance between the experiments was confirmed by the Cochran test. With the addition of CRH to the substrate, there was an increase in total porosity and P content and a reduction in density, water holding capacity, cation exchange capacity, electrical conductivity, and N, K, S, Ca and Mg contents. The carbonized rice husk added to the commercial substrate is a viable alternative for the production of lettuce, broccoli and mustard seedlings. The quality of the vegetable seedlings was higher when there was a 25% CRH + 75% CS mixture.

A Physiological behavior and tolerance of Lactuca sativa to lead nitrate and silver nitrate heavy metals / Comportamento fisiológico e tolerância de Lactuca sativa aos metais pesados nitrato de chumbo e nitrato de prata

This study goal to evaluate the effects of different concentrations of lead (Pb) and silver (Ag) on germination, initial growth and anatomical alterations of Lactuca sativa L. Plants use various mechanisms to reduce the impacts caused by anthropic action, such as xenobiotic elements of soils and water contaminated by heavy metals. These metals were supplied as lead nitrate and silver nitrate and the following treatments were established: control for both metals, maximum dose of heavy metals, for arable soils, allowed by the National Council of the Environment (Ag = 25 mg. Kg-¹, Pb = 180 mg. Kg-¹), double (Ag = 50 mg. Kg-¹, Pb = 360 mg. Kg-¹) and triple (Ag = 75 mg. Kg-¹, Pb = 540 mg. Kg-¹) of this dosage. Vigor and germination tests of the seeds and possible anatomical changes in the leaves and roots of lettuce plants were performed. The species showed a high capacity to germinate under Pb and Ag stress, and the germination was never completely inhibited; however, the germination decreased with increasing Pb concentrations, but not under Ag stress. The use of increasing doses of metals reduced seed vigor and increased chlorophyll content. An increase in biomass was also observed in plants from treatments submitted to Pb. The phytotoxic effects of metals were more pronounced at 15 days after sowing. Anatomically, L. sativa was influenced by metal concentrations, and had a reduction of up to 79.9% in root epidermis thickness at the highest Pb concentration, although some structures did not suffer significant changes. The results suggest that L. sativa presents tolerance to high concentrations of heavy metals, showing possible mechanisms to overcome the stress caused by these metals. In this research lettuce possibly used the mechanism of exclusion of metals retaining Pb and Ag in the roots preserving the photosynthetic apparatus in the aerial part of the plants. In general, the chemical element Pb was more toxic than Ag, in these experimental conditions.

Este estudo teve como objetivo avaliar os efeitos de diferentes concentrações de chumbo (Pb) e prata (Ag) na germinação, crescimento inicial e alterações anatômicas de Lactuca sativa L. As plantas utilizam vários mecanismos para reduzir os impactos causados pela ação antrópica, como elementos xenobióticos de solos e água contaminada por metais pesados. Esses metais foram fornecidos como nitrato de chumbo e nitrato de prata e foram estabelecidos os seguintes tratamentos:controle para ambos os metais, dose máxima de metais pesados, para solos cultiváveis, permitida pelo Conselho Nacional do Meio Ambiente (Ag = 25mg.Kg-¹, Pb = 180mg.Kg-¹), dobro (Ag = 50mg.Kg-¹, Pb = 360mg.Kg-¹) e triplo (Ag = 75mg.Kg-¹, Pb = 540 mg.Kg-¹) desta dosagem. Foram realizados testes de vigor e germinação das sementes e possíveis alterações anatômicas nas folhas e raízes das plantas de alface. A espécie apresentou alta capacidade de germinar sob estresse de Ag e Pb, e a germinação nunca foi completamente inibida; entretanto, a germinação diminuiu com o aumento das concentrações de Pb, mas não sob estresse de Ag. O uso de doses crescentes dos metais, reduziu o vigor das sementes e aumentou o teor de clorofila. Também foi observado aumento da biomassa nas plantas a partir dos tratamentos submetidos ao Pb. Os efeitos fitotóxicos dos metais foram mais acentuados aos 15 dias após a semeadura. Anatomicamente, L. sativa foi influenciada pelas concentrações de metais, e teve uma redução de até 79,9% na espessura da epiderme radicular na maior concentração de Pb, embora algumas estruturas não tenham sofrido alterações significativas. Os resultados sugerem que L. sativa apresenta tolerância a altas concentrações de metais pesados, mostrando possíveis mecanismos para superar o estresse causado por esses metais. Nesta pesquisa a alface possivelmente utilizou o mecanismo de exclusão de metais retendo Pb e Ag nas raízes preservando o aparato [...].

Detection of enteroparasites in foliar vegetables commercialized in street- and supermarkets in Aparecida de Goiânia, Goiás, Brazil / Detecção de enteroparasitas em hortaliças comercializadas em feiras e supermercados em Aparecida de Goiânia, Goiás, Brasil

Foliar vegetables contaminated with fecal residues are an important route of transmission of intestinal parasites to humans. The aim of this study was to evaluate the presence of parasitic forms of protozoa and helminths on lettuces (Lactuca sativa) and collard greens (Brassica oleracea) sold in street- and supermarkets in the city of Aparecida de Goiânia, Goiás, Brazil. A total of 30 samples of each vegetable (15 samples from each supermarkets and street markets) was analyzed. All samples were processed by spontaneous sedimentation method and centrifugal flotation. In 45% of the samples, immature forms of intestinal parasites were identified with 66.7% helminths eggs and 33.3% protozoan cysts or oocysts. Significantly more lettuce samples were contaminated with eggs, cysts or oocyst of at least one parasite than collard green samples (U=216; Z=-3.45; P <0.001). The parasitic forms were identified morphologically up to the family level with eggs of Ancylostomatidae, Strongyloididae, Ascarididae and Taeniidae, or oocysts of Eimeriidae, to the genus with Cystoisospora sp. and Toxocara sp., and to the species level with Cystoisospora canis, Dipylidium caninum and Hymenolepis nana. The presence of these infective agents in lettuce and collard green from both street- and supermarkets highlights the high risk of spreading parasites by eating raw vegetables sold in Aparecida de Goiânia.

Hortaliças contaminadas com resíduos fecais são importantes vias de transmissão de parasitas intestinais ao homem. O objetivo deste estudo foi avaliar a presença de formas parasitárias de protozoários e helmintos em alface (Lactuca sativa) e couve (Brassica oleracea) vendidas em feiras e supermercados na cidade de Aparecida de Goiânia, Goiás, Brasil. Um total de 30 amostras de cada vegetal (15 amostras de supermercados e 15 de feiras livres) foi analisado. Todas as amostras foram processadas pelos métodos de sedimentação espontânea e centrífugo-flutuação. Em 45% das amostras foram identificadas formas imaturas de parasitas intestinais sendo 66,7% ovos de helmintos e 33,3% de cistos ou oocistos de protozoários. Significativamente, mais amostras de alface estavam contaminadas com ovos, cistos ou oocistos de pelo menos um parasita do que as amostras de couve (U = 216; Z = -3,45; P <0,001). As formas parasitárias foram identificadas morfologicamente ao nível de família com ovos de Ancylostomatidae, Strongyloididae, Ascarididae e Taeniidae ou oocistos de Eimeriidae, dos gêneros Cystoisospora sp. e Toxocara sp., e ao nível de espécies com Cystoisospora canis, Dipylidium caninum e Hymenolepis nana. A presença desses agentes infecciosos em alface e couve, provenientes tanto de feiras quanto de supermercados, ressalta o alto risco de veiculação de parasitas pela ingestão de hortaliças cruas comercializadas em Aparecida de Goiânia.

A Physiological behavior and tolerance of Lactuca sativa to lead nitrate and silver nitrate heavy metals

Abstract This study goal to evaluate the effects of different concentrations of lead (Pb) and silver (Ag) on germination, initial growth and anatomical alterations of Lactuca sativa L. Plants use various mechanisms to reduce the impacts caused by anthropic action, such as xenobiotic elements of soils and water contaminated by heavy metals. These metals were supplied as lead nitrate and silver nitrate and the following treatments were established: control for both metals, maximum dose of heavy metals, for arable soils, allowed by the National Council of the Environment (Ag = 25 mg. Kg-1, Pb = 180 mg. Kg-1), double (Ag = 50 mg. Kg-1, Pb = 360 mg. Kg-1) and triple (Ag = 75 mg. Kg-1, Pb = 540 mg. Kg -1) of this dosage. Vigor and germination tests of the seeds and possible anatomical changes in the leaves and roots of lettuce plants were performed. The species showed a high capacity to germinate under Pb and Ag stress, and the germination was never completely inhibited; however, the germination decreased with increasing Pb concentrations, but not under Ag stress. The use of increasing doses of metals reduced seed vigor and increased chlorophyll content. An increase in biomass was also observed in plants from treatments submitted to Pb. The phytotoxic effects of metals were more pronounced at 15 days after sowing. Anatomically, L. sativa was influenced by metal concentrations, and had a reduction of up to 79.9% in root epidermis thickness at the highest Pb concentration, although some structures did not suffer significant changes. The results suggest that L. sativa presents tolerance to high concentrations of heavy metals, showing possible mechanisms to overcome the stress caused by these metals. In this research lettuce possibly used the mechanism of exclusion of metals retaining Pb and Ag in the roots preserving the photosynthetic apparatus in the aerial part of the plants. In general, the chemical element Pb was more toxic than Ag, in these experimental conditions.

Resumo Este estudo teve como objetivo avaliar os efeitos de diferentes concentrações de chumbo (Pb) e prata (Ag) na germinação, crescimento inicial e alterações anatômicas de Lactuca sativa L. As plantas utilizam vários mecanismos para reduzir os impactos causados pela ação antrópica, como elementos xenobióticos de solos e água contaminada por metais pesados. Esses metais foram fornecidos como nitrato de chumbo e nitrato de prata e foram estabelecidos os seguintes tratamentos: controle para ambos os metais, dose máxima de metais pesados, para solos cultiváveis, permitida pelo Conselho Nacional do Meio Ambiente (Ag = 25 mg.Kg-1, Pb = 180 mg.Kg-1), dobro (Ag = 50 mg.Kg-1, Pb = 360 mg.Kg-1) e triplo (Ag = 75 mg.Kg-1, Pb = 540 mg.Kg -1) desta dosagem. Foram realizados testes de vigor e germinação das sementes e possíveis alterações anatômicas nas folhas e raízes das plantas de alface. A espécie apresentou alta capacidade de germinar sob estresse de Ag e Pb, e a germinação nunca foi completamente inibida; entretanto, a germinação diminuiu com o aumento das concentrações de Pb, mas não sob estresse de Ag. O uso de doses crescentes dos metais, reduziu o vigor das sementes e aumentou o teor de clorofila. Também foi observado aumento da biomassa nas plantas a partir dos tratamentos submetidos ao Pb. Os efeitos fitotóxicos dos metais foram mais acentuados aos 15 dias após a semeadura. Anatomicamente, L. sativa foi influenciada pelas concentrações de metais, e teve uma redução de até 79,9% na espessura da epiderme radicular na maior concentração de Pb, embora algumas estruturas não tenham sofrido alterações significativas. Os resultados sugerem que L. sativa apresenta tolerância a altas concentrações de metais pesados, mostrando possíveis mecanismos para superar o estresse causado por esses metais. Nesta pesquisa a alface possivelmente utilizou o mecanismo de exclusão de metais retendo Pb e Ag nas raízes preservando o aparato fotossintético na parte aérea das plantas. De forma geral o elemento químico Pb se mostrou mais tóxico que Ag, nestas condições experimentais.

Detection of enteroparasites in foliar vegetables commercialized in street- and supermarkets in Aparecida de Goiânia, Goiás, Brazil

Abstract Foliar vegetables contaminated with fecal residues are an important route of transmission of intestinal parasites to humans. The aim of this study was to evaluate the presence of parasitic forms of protozoa and helminths on lettuces (Lactuca sativa) and collard greens (Brassica oleracea) sold in street- and supermarkets in the city of Aparecida de Goiânia, Goiás, Brazil. A total of 30 samples of each vegetable (15 samples from each supermarkets and street markets) was analyzed. All samples were processed by spontaneous sedimentation method and centrifugal flotation. In 45% of the samples, immature forms of intestinal parasites were identified with 66.7% helminths eggs and 33.3% protozoan cysts or oocysts. Significantly more lettuce samples were contaminated with eggs, cysts or oocyst of at least one parasite than collard green samples (U=216; Z=-3.45; P 0.001). The parasitic forms were identified morphologically up to the family level with eggs of Ancylostomatidae, Strongyloididae, Ascarididae and Taeniidae, or oocysts of Eimeriidae, to the genus with Cystoisospora sp. and Toxocara sp., and to the species level with Cystoisospora canis, Dipylidium caninum and Hymenolepis nana. The presence of these infective agents in lettuce and collard green from both street- and supermarkets highlights the high risk of spreading parasites by eating raw vegetables sold in Aparecida de Goiânia.

Resumo Hortaliças contaminadas com resíduos fecais são importantes vias de transmissão de parasitas intestinais ao homem. O objetivo deste estudo foi avaliar a presença de formas parasitárias de protozoários e helmintos em alface (Lactuca sativa) e couve (Brassica oleracea) vendidas em feiras e supermercados na cidade de Aparecida de Goiânia, Goiás, Brasil. Um total de 30 amostras de cada vegetal (15 amostras de supermercados e 15 de feiras livres) foi analisado. Todas as amostras foram processadas pelos métodos de sedimentação espontânea e centrífugo-flutuação. Em 45% das amostras foram identificadas formas imaturas de parasitas intestinais sendo 66,7% ovos de helmintos e 33,3% de cistos ou oocistos de protozoários. Significativamente, mais amostras de alface estavam contaminadas com ovos, cistos ou oocistos de pelo menos um parasita do que as amostras de couve (U = 216; Z = -3,45; P 0,001). As formas parasitárias foram identificadas morfologicamente ao nível de família com ovos de Ancylostomatidae, Strongyloididae, Ascarididae e Taeniidae ou oocistos de Eimeriidae, dos gêneros Cystoisospora sp. e Toxocara sp., e ao nível de espécies com Cystoisospora canis, Dipylidium caninum e Hymenolepis nana. A presença desses agentes infecciosos em alface e couve, provenientes tanto de feiras quanto de supermercados, ressalta o alto risco de veiculação de parasitas pela ingestão de hortaliças cruas comercializadas em Aparecida de Goiânia.

Detection of enteroparasites in foliar vegetables commercialized in street- and supermarkets in Aparecida de Goiânia, Goiás, Brazil / Detecção de enteroparasitas em hortaliças comercializadas em feiras e supermercados em Aparecida de Goiânia, Goiás, Brasil

Foliar vegetables contaminated with fecal residues are an important route of transmission of intestinal parasites to humans. The aim of this study was to evaluate the presence of parasitic forms of protozoa and helminths on lettuces (Lactuca sativa) and collard greens (Brassica oleracea) sold in street- and supermarkets in the city of Aparecida de Goiânia, Goiás, Brazil. A total of 30 samples of each vegetable (15 samples from each supermarkets and street markets) was analyzed. All samples were processed by spontaneous sedimentation method and centrifugal flotation. In 45% of the samples, immature forms of intestinal parasites were identified with 66.7% helminths eggs and 33.3% protozoan cysts or oocysts. Significantly more lettuce samples were contaminated with eggs, cysts or oocyst of at least one parasite than collard green samples (U=216; Z=-3.45; P <0.001). The parasitic forms were identified morphologically up to the family level with eggs of Ancylostomatidae, Strongyloididae, Ascarididae and Taeniidae, or oocysts of Eimeriidae, to the genus with Cystoisospora sp. and Toxocara sp., and to the species level with Cystoisospora canis, Dipylidium caninum and Hymenolepis nana. The presence of these infective agents in lettuce and collard green from both street- and supermarkets highlights the high risk of spreading parasites by eating raw vegetables sold in Aparecida de Goiânia.

Hortaliças contaminadas com resíduos fecais são importantes vias de transmissão de parasitas intestinais ao homem. O objetivo deste estudo foi avaliar a presença de formas parasitárias de protozoários e helmintos em alface (Lactuca sativa) e couve (Brassica oleracea) vendidas em feiras e supermercados na cidade de Aparecida de Goiânia, Goiás, Brasil. Um total de 30 amostras de cada vegetal (15 amostras de supermercados e 15 de feiras livres) foi analisado. Todas as amostras foram processadas pelos métodos de sedimentação espontânea e centrífugo-flutuação. Em 45% das amostras foram identificadas formas imaturas de parasitas intestinais sendo 66,7% ovos de helmintos e 33,3% de cistos ou oocistos de protozoários. Significativamente, mais amostras de alface estavam contaminadas com ovos, cistos ou oocistos de pelo menos um parasita do que as amostras de couve (U = 216; Z = -3,45; P <0,001). As formas parasitárias foram identificadas morfologicamente ao nível de família com ovos de Ancylostomatidae, Strongyloididae, Ascarididae e Taeniidae ou oocistos de Eimeriidae, dos gêneros Cystoisospora sp. e Toxocara sp., e ao nível de espécies com Cystoisospora canis, Dipylidium caninum e Hymenolepis nana. A presença desses agentes infecciosos em alface e couve, provenientes tanto de feiras quanto de supermercados, ressalta o alto risco de veiculação de parasitas pela ingestão de hortaliças cruas comercializadas em Aparecida de Goiânia.

A Physiological behavior and tolerance of Lactuca sativa to lead nitrate and silver nitrate heavy metals / Comportamento fisiológico e tolerância de Lactuca sativa aos metais pesados nitrato de chumbo e nitrato de prata

This study goal to evaluate the effects of different concentrations of lead (Pb) and silver (Ag) on germination, initial growth and anatomical alterations of Lactuca sativa L. Plants use various mechanisms to reduce the impacts caused by anthropic action, such as xenobiotic elements of soils and water contaminated by heavy metals. These metals were supplied as lead nitrate and silver nitrate and the following treatments were established: control for both metals, maximum dose of heavy metals, for arable soils, allowed by the National Council of the Environment (Ag = 25 mg. Kg-1, Pb = 180 mg. Kg-1), double (Ag = 50 mg. Kg-1, Pb = 360 mg. Kg-1) and triple (Ag = 75 mg. Kg-1, Pb = 540 mg. Kg -1) of this dosage. Vigor and germination tests of the seeds and possible anatomical changes in the leaves and roots of lettuce plants were performed. The species showed a high capacity to germinate under Pb and Ag stress, and the germination was never completely inhibited; however, the germination decreased with increasing Pb concentrations, but not under Ag stress. The use of increasing doses of metals reduced seed vigor and increased chlorophyll content. An increase in biomass was also observed in plants from treatments submitted to Pb. The phytotoxic effects of metals were more pronounced at 15 days after sowing. Anatomically, L. sativa was influenced by metal concentrations, and had a reduction of up to 79.9% in root epidermis thickness at the highest Pb concentration, although some structures did not suffer significant changes. The results suggest that L. sativa presents tolerance to high concentrations of heavy metals, showing possible mechanisms to overcome the stress caused by these metals. In this research lettuce possibly used the mechanism of exclusion of metals retaining Pb and Ag in the roots preserving the photosynthetic apparatus in the aerial part of the plants. In general, the chemical element Pb was more toxic than Ag, in these experimental conditions.

Este estudo teve como objetivo avaliar os efeitos de diferentes concentrações de chumbo (Pb) e prata (Ag) na germinação, crescimento inicial e alterações anatômicas de Lactuca sativa L. As plantas utilizam vários mecanismos para reduzir os impactos causados pela ação antrópica, como elementos xenobióticos de solos e água contaminada por metais pesados. Esses metais foram fornecidos como nitrato de chumbo e nitrato de prata e foram estabelecidos os seguintes tratamentos: controle para ambos os metais, dose máxima de metais pesados, para solos cultiváveis, permitida pelo Conselho Nacional do Meio Ambiente (Ag = 25mg.Kg-1, Pb = 180mg.Kg-1), dobro (Ag = 50mg.Kg-1, Pb = 360mg.Kg-1) e triplo (Ag = 75mg.Kg-1, Pb = 540 mg.Kg -1) desta dosagem. Foram realizados testes de vigor e germinação das sementes e possíveis alterações anatômicas nas folhas e raízes das plantas de alface. A espécie apresentou alta capacidade de germinar sob estresse de Ag e Pb, e a germinação nunca foi completamente inibida; entretanto, a germinação diminuiu com o aumento das concentrações de Pb, mas não sob estresse de Ag. O uso de doses crescentes dos metais, reduziu o vigor das sementes e aumentou o teor de clorofila. Também foi observado aumento da biomassa nas plantas a partir dos tratamentos submetidos ao Pb. Os efeitos fitotóxicos dos metais foram mais acentuados aos 15 dias após a semeadura. Anatomicamente, L. sativa foi influenciada pelas concentrações de metais, e teve uma redução de até 79,9% na espessura da epiderme radicular na maior concentração de Pb, embora algumas estruturas não tenham sofrido alterações significativas. Os resultados sugerem que L. sativa apresenta tolerância a altas concentrações de metais pesados, mostrando possíveis mecanismos para superar o estresse causado por esses metais. Nesta pesquisa a alface possivelmente utilizou o mecanismo de exclusão de metais retendo Pb e Ag nas raízes preservando o aparato fotossintético na parte aérea das plantas. De forma geral o elemento químico Pb se mostrou mais tóxico que Ag, nestas condições experimentais.

Aproveitamento de resíduos de pescado na confecção de composto orgânico para produção de mudas de alface / Use of fish waste in the production of organic compounds for lettuce seedling production

RESUMO Há muitos estudos voltados à redução do volume de resíduos provenientes da indústria pesqueira. Esses resíduos são uma importante fonte de matéria-prima em sistemas orgânicos de produção ao serem compostados. O objetivo deste trabalho foi avaliar os parâmetros teores totais de nutrientes do composto orgânico confeccionado com resíduos de pescado, comparando-o a outras duas composições, além de utilizá-lo como substrato na produção de mudas de alface (Lactuca sativa). Na avaliação de produção de mudas de alface, utilizou-se o delineamento inteiramente casualizado, com seis tratamentos e quatro repetições. Avaliaram-se: quantidade de folhas (QF), comprimento da raiz (CR), massa seca da parte aérea (MSPA) e massa seca da raiz (MSR). Os parâmetros de matéria orgânica (MO), relação C/N e capacidade de troca de cátions (CTC) foram superiores no composto de resíduo de pescado. Para a produção de MSPA, os tratamentos T3 (composto confeccionado com resíduos de pescado) e T2 (composto confeccionado com resíduos agroindustriais da palmeira carnaúba) apresentaram as maiores médias, sendo T2 o que apresentou a maior média para MSR. Para QF, os melhores resultados (p = 0,02) foram obtidos pelo tratamento T6, cujas mudas de alface apresentaram maior QF e CR. Os resultados sugerem viabilidade na produção de mudas de alface utilizando substrato à base de resíduos de pescado.

ABSTRACT There are many studies aimed at reducing the volume of waste from the fishing industry. These residues are an important source of raw material in organic production systems when composted. The objective of this work was to evaluate the parameters of total nutrient contents of the organic compost made with fish residues, comparing it to two other compositions, in addition to using it as substrate in the production of lettuce seedlings (Lactuca sativa). In the evaluation of lettuce seedlings production, a completely randomized design was used, with six treatments and four replications. The following were evaluated: Leaf quantity (QF), root length (CR), Aerial part dry mass (MSPA), and root dry mass (MSR). The parameters of organic matter (OM), C/N ratio and cation exchange capacity (CTC) were higher in the fish residue compound. For the production of MSPA, treatments T3 (compound made with fish residues) and T2 presented the highest averages, being treatment T2 (compound made with agroindustrial residues of the Carnauba palm) presented the highest averages, with T2 presenting the highest mean for MSR. For QF, the best results (p = 0.02) were obtained by T6 treatment, whose lettuce seedlings had a greater number of leaves and root length. The results suggest viability in the production of lettuce seedlings using a substrate based on fish residues.

Contaminação por enteroparasitas em Alfaxces (Lactuca sativa) comercializadas na cidad de Araraquara (SP) e na micro-região (Américo Brasiliense, Matão, Santa Lúcia, Rincão e Taquaritinga),Brasil / Enteroparasite contamination in Alfaces (Lactuca sativa) commercialized in the city of Araraquara (SP) and in the micro region (Américo Brasiliense, Matão Santa Lúcia Rincão and Taquaritinga), Brazil

Objetivo ­ Conhecer o estado higiênico-sanitário de alfaces (Lactuca sativa) comercializadas na cidade de Araraquara e região (Américo Brasiliense,Matão, Santa Lúcia, Rincão e Taquaritina) SP, quanto a presença de enteroparasitas. Métodos ­ As amostras foram adquiridas em diversos tipos de estabelecimentos (alface in natura) ou em restaurantes self-service, prontas para consumo; as folhas (250 g para folhas in natura e 150 g para folhas prontas para consumo, aproximadamente) foram friccionadas por 5 min em saco plástico contendo 300 ml de solução NaCl 0,9% com 1% de detergente neutro e o líquido de lavagem, após filtração por gaze, sedimentado por 24 horas; o sedimento foi avaliado por exame microscópico direto e também após ser submetido ao método de Faust. Resultados ­ 53% das amostras in natura avaliadas apresentaram algum tipo de contaminação por enteroparasitas (larvas de Helmintos, cistos de protozoários intestinais e ovos de helmintos), sendo que a maior parte das amostras avaliadas foram comercializadas em supermercados na cidade de Araraquara. Na alface pronta para consumo, foi encontrada elevada sujicidade em 3 das 10 amostras analisadas. Conclusão ­ Os resultados obtidos reforçam a necessidade de cuidados de higiene durante toda a cadeia de produção e comercialização da alface, e principalmente no alimento pronto para consumo

Objective ­ To know the hygienic-sanitary state of lettuces (Lactuca sativa) in natura and hygienized commercialized in the city of Araraquara and region (Américo Brasiliense, Matão, Santa Lucia, Rincão and Taquaritina) SP, as for the presence of enteroparasites. Methods ­ The samples were obtained in several types of establishments (lettuce in natura) or self-service restaurants ready for consumption; the sheets were rubbed for 5 min in a plastic bag containing 300 ml 0.9% NaCl solution with 1% neutral detergent and the washing liquid settled for 24 hours; the sediment was evaluated by direct microscopic examination and also after being submitted to the Faust method. Results ­ 53% of the in natura samples evaluated showed some type of enteroparasite contamination (helminth larvae, intestinal protozoa cysts and helminth eggs), and most samples were commercialized in supermarkets in the city of Araraquara. In the ready - to - eat lettuce, high dirt was found in 3 of the 10 analyzed samples. Conclusion ­ The results obtained reinforce the need for hygiene care throughout the production chain and commercialization of lettuce, but mainly in food ready for consumption

Response of Bioactive Phytochemicals in Vegetables and Fruits to Environmental Factors

This review focused on the influence of environmental systems and/or factors including high tunnel, UV and visible light, fertilization, and irrigation on bioactive compounds in vegetables and fruits. Most studies reported that high tunnel reduced chicoric acid and luteolin in vegetables including lettuce and pac choi, and fruits including raspberry and tomato versus open field, although a few studies demonstrated that high tunnel did not significantly impact on the bioactive compounds. Light including UV such as photosynthetically active radiation (PAR), UV-A, and UV-B, and visible light especially red and blue light, significantly stimulated biosynthesis of anthocyanins, flavonoids, and phenolics, and promoted their contents in vegetables such as onion and spinach, and fruits for example blueberry and strawberry. The effect of fertilization including nitrogen, phosphorus, and potassium on bioactive phytochemicals (carotenoids, flavonoids, polyphenols) in vegetables (broccoli, kale) or fruits (tomato) varied among the cultivars. Water deficit usually increased anthocyanins, flavonoids, and phenolic acids in vegetables such as lettuce and red beet, and fruits including grape and pomegranate. Taken together, the bioactive compounds in vegetables and fruits in response to environmental factors were species- and varieties- dependent. The negative effect of environmental factors on bioactive compounds in vegetables and fruits can be overcome by selecting appropriate cultivars, while the positive effect can be further manipulated in horticultural production for potential consumer’s health benefits.

Influence of symbiotic bacteria from lettuce on inactivation of norovirus / 预防医学

Objective@#To demonstrate the effects of symbiotic bacteria from lettuce on inactivation of norovirus（NV）.@*Methods@#Symbiotic bacteria were isolated from the lettuces sampled from farmlands and supermarkets. NV mixed with symbiotic bacteria was set as the experimental group,without symbiotic bacteria as the control group. After the inactivation by high temperature,ultraviolet light（UV）and chlorine dioxide,the ratio of NV amount in the experimental group and the control group was calculated to evaluate the effects of symbiotic bacteria. The mechanism of symbiotic bacteria was revealed by detecting their effects on the protection of viral capsid protein from UV and on the adsorption of NV.@*Results@#Eleven symbiotic bacteria were identified from lettuces,all of which were bacilli,mainly Pseudomonas. Ten symbiotic bacteria could improve the heat-resistant ability of NV,with Microbacterium oryzae,Cupriavidus taiwanensis（SC061204）,Pseudomonas furukawaii,Enterobacter tabaci and Pseudomonas resinovorans（SC061211）more significant. Eleven symbiotic bacteria could improve anti-UV ability of NV,with Pseudomonas putida,Microbacterium oryzae and Enterobacter tabaci more significant. Only one strain of Pseudomonas putida could improve anti-chlorine dioxide ability of NV（Class I hazard）. Pseudomonas putida,Microbacterium oryzae and Enterobacter tabaci could significantly reduce the damage of NV capsid protein. Nine symbiotic bacteria could promote NV adsorption into lettuces,with the promotion rates ranged from 1.04% to 46.73%;while Pseudomonas putida and Pseudomonas resinovorans（SC061211） could restrain NV absorption,with the promotion rates of -6.50% and -19.85%.@*Conclusion@#Symbiotic bacteria from lettuce may enhance the anti-inactivation of NV by protecting capsid protein and promoting adsorption of NV. It is recommended to control the presence of symbiotic bacteria in the process of inactivating NV.

Determinación de enteroparásitos en Lactuca sativa en fincas dedicadas a su producción en Pasto, Colombia / Enteroparasite determination in Lactuca sativa from farms dedicated to its production in Pasto, Colombia

Resumen Introducción. Actualmente se recomienda incluir en la dieta diaria verduras como la lechuga por su gran aporte nutricional; sin embargo, atraídos por tales beneficios, los consumidores pueden estar expuestos a infecciones con parásitos intestinales. Objetivo. Determinar la presencia o ausencia de enteroparásitos en la lechuga (Lactuca sativa) cultivada en la zona rural del municipio de Pasto y, una vez caracterizados los predios, analizar los factores asociados. Materiales y métodos. Se hizo un estudio transversal doble ciego de tipo descriptivo. Se tomaron 105 muestras de 21 predios entre junio y diciembre de 2013 y se procesaron mediante pruebas de flotación y sedimentación. Además, se encuestó a los propietarios de los predios para obtener información sobre las variables que pudieran determinar la aparición de enteroparásitos. Resultados. Se encontró contaminación con huevos y larvas de parásitos en 100 % de las muestras: 95,25 % con quistes de Entamoeba spp.; 71,43% con ooquistes de Isospora spp.; 61,90% con larvas (L3) de Strongyloides stercoralis; 28,57 % con huevos de Toxocara spp., y 4,76 % con ooquistes de Eimeria spp. En cuanto a los factores asociados según la prueba de ji al cuadrado, se encontró relación entre Entamoeba spp. y las acequias (p=0,008), los perros (p=0,008) y los pozos sépticos (p=0,029); entre Isospora spp. y el compost (p=0,0001), los perros (p=0,0001) y las babosas (p=0,002); entre S. stercoralis y la manipulación (p=0,003), y entre Toxocara spp. y el hecho de no utilizar biodigestores (p=0,002). Conclusiones. En las áreas de cultivo del municipio de Pasto se encontró contaminación de las muestras de lechuga con enteroparásitos provenientes principalmente de reservorios animales y humanos, aunque también presentes en el medio ambiente.

Abstract Introduction: Currently, vegetables like lettuce are widely recommended as part of the daily diet given their high nutritional value; however, while consumers feel attracted to the benefits provided by the vegetable, they may also be exposed to parasitic intestinal infections. Objective: To determine the presence or absence of enteroparasites in lettuce (Lactuca sativa) grown in the rural area in the municipality of Pasto, and to analyze associated factors based on the characterization of the lands. Materials and methods: We conducted a descriptive double blind cross-sectional study. We took a total of 105 samples from 21 properties from June to December, 2013, and we processed them by sedimentation and flotation tests. Additionally, the owners were surveyed in order to obtain information about the possible variables influencing the occurrence of enteroparasites. Results: We detected contamination in 100% of the lettuce samples and we found parasite eggs and larvae as follows: 95.25% with Entamoeba spp. cysts; 71.43% with Isospora spp. oocysts; 61.90% with Strongyloides stercoralis larvae (L3); 28.57% with Toxocara spp. eggs, and 4.76% with Eimeria spp. oocysts. Using the chi-square test we found association between Entamoeba spp. and ditches (p=0.008), dogs (p=0.008) and septic tanks (p=0.029); between Isospora spp. and compost (p=0.0001), dogs (p=0.0001) and slugs (p=0.002); between S. stercoralis and handling (p=0.003), and between Toxocara spp. and no use of biodigesters (p= 0.002). Conclusions: We found contamination with enteroparasites in lettuce samples from growing areas in the municipality of Pasto with animal and human sources as their main reservoirs, although others were present in the environment.

Tannin extracts on quality of fresh cut crisp leaf lettuce / Extratos de taninos na qualidade de alface crespa minimamente processada

ABSTRACT: In the present study, tannin extracts (rinsed or not) were compared to the use of sodium hypochlorite and tap water on fresh cut crisp leaf lettuce stored under modified atmosphere packaging. Effects of these sanitizers on total color difference and microbial levels of the product after sanitization and storage for 9 days at 3°C were evaluated. Performance of rinsed SM(r) tannin extract was comparable to the results of chlorine solution for all the analyzed parameters and; furthermore, that extract presented a high reduction in the initial bacterial count of minimally processed lettuce. However, storage of tannin extracts, did not impart better outcomes than the use of tap water. Therefore, the tannin extract storage SM(r) could be used in washing water to reduce the initial microbiological load, avoiding cross contamination in vegetables minimally processed.

RESUMO: Extratos de taninos (com e sem enxague) foram comparados com o uso de hipoclorito de sódio e água em alface crespa minimamente processada, sob atmosfera modificada. Foram avaliadas diferença total de cor e análises microbiológicas após a sanitização e durante o armazenamento dos produtos (9 dias à 3°C). O extrato de tanino SM(r) com enxague apresentou resultados semelhantes aos da solução de cloro para todos os parâmetros analisados e, além disso, apresentou uma elevada redução da contagem inicial microbiológica de alface minimamente processada. No entanto, durante o armazenamento, SM(r) não apresentou melhores resultados do que o uso de água. Portanto, SM(r) poderia ser utilizado na desinfecção da água de lavagem das alfaces, reduzindo a microbiota inicial e, assim, impedir a contaminação cruzada durante o processamento mínimo de vegetais.

Evaluación de la contaminación microbiológica de la lechuga (lactuca sativa) en la cadena alimentaria, provincia de Quillacollo, Cochabamba, Bolivia 2015 / Evaluation of microbiological contamination of lettuce (Lactuca sativa) in the food chain, province of Quillacollo, Cochabamba, Bolivia 2015

Las enfermedades transmitidas por alimentos constituyen un problema de salud, diversos estudios demuestran la alta contaminación microbiológica de la lechuga en la cadena alimentaria. El objetivo de la presente investigación fue evaluar la contaminación microbio-lógica de la lechuga (Lactuca sativa) en la cadena alimentaria, en la provincia Quillacollo-Cochabamba-Bolivia. Muestras de lechugas fueron tomadas en los meses de abril y mayo, con el mismo de número de muestras, en tres puntos de la cadena alimentaria: parcelas de producción (localidad Combuyo), puestos de venta de lechuga y de comida de los Mercados 9 de diciembre y Central de Quillacollo. El procesamiento de las muestras fue realizado en los laboratorios de Microbiología de LABIMED, y Post Grado de Medicina Tropical de la Facultad de Medicina, UMSS. Los resultados demuestran la contaminación de las lechugas con bacterias Aerobias Mesófilas, colifor-mes totales y fecales en concentraciones superiores a los estándares permitidos en los tres puntos de la cadenas alimentaria evaluadas; identificándose Salmonella sp en una de las muestras de lechugas procesada de los puestos de venta de comida de los mercados. La contaminación parasitaria fue evidenciada en los puestos de venta solo en el mes de mayo en 83% (n=10) de las 12 muestras analizadas, detectándose quistes de Entamoeba coli y larvas de Strongyloides sp, contaminación relacionada con la utilización de abono de aves en el cultivo y la manipulación inadecuada de la lechuga en la cadena alimentaria. En conclusión podemos indicar que las lechugas presentan una importante contaminación microbiana en los tres puntos evaluados de la cadena alimentaria, por lo que constituye un riego para la salud pública.

Infectious diseases transmitted by food, are considered a public health issue, several studies shown the high microbiological contamination of the letucce in particular (Lactuca sativa). The aim of this study was to evaluate the contamination of letucce at Quillacollo Province of Cochabamba- Bolivia. The samples were taken between april and may, with the same number of samples at production plots (Combuyo location), and at selling places of vegetables and food (markets) such as "9 de diciembre” market and "Central Quillacollo” market. The samples were processed at LABIMED laboratories (microbiology, and Tropical Medicine Post grade of medicine Faculty of San Simón University). Results shows contamination of lettuce with Aerobic Mesophilic Bacterias, and total coliforms and fecal coliforms, in higher concentration than standard allowed, at any point of chain food that has been evaluate; Sallmonella sp was identify at selling points with 83% of the samples and only at the month of may (n=10 of 12 samples examined) also Entamoeba coli cysts and Strongyloides sp worms; the contamination was associate with bird fertilizer at crops and at inapropiate food management of the lettuce. Therefore we can conclude that lettuce's contamination is present at the three evaluated points of its chain, production selling points until consume, wich must be considered as a public health risk.

Vida de prateleira de alface americana tratada com água ozonizada / Shelf life evaluation of the iceberg lettuce sanitized with ozone water

RESUMO:Este trabalho avaliou se a higienização de alface americana com água ozonizada, na concentração de 1,0mg L-1 por 1, 2 ou 3 minutos, seria capaz de aumentar a vida útil do produto quando armazenado a 2ºC. Foram avaliadas as populações de microrganismos aeróbios mesófilos, Enterobacteriaceae, bolores e leveduras, coliformes totais, coliformes termotolerantes e pesquisa de Salmonellasp ao longo do tempo. Imediatamente após o processamento por 3 minutos, foram obtidas reduções decimais de 4,07; 3,36; 3,20; 2,18 e 2,18 de microrganismos aeróbios mesófilos,Enterobacteriaceae, bolores e leveduras, coliformes totais, coliformes termotolerantes, respectivamente. A presença de Salmonellasp. não foi observada em nenhuma das condições estudadas. Além do efeito na inativação inicial, o processamento com ozônio melhorou a estabilidade da alface durante a estocagem, aumentando o tempo para o início do crescimento microbiano (de zero para quatro dias) e reduzindo a taxa de crescimento dos microrganismos, especialmente quando a sanitização foi realizada por 3 minutos de contato. Os resultados demonstraram que a alface tratada com água ozonizada atendeu aos parâmetros da legislação durante o período avaliado, reduzindo a contaminação inicial das alfaces (que, sem tratamento, estavam microbiologicamente impróprias para consumo pela contagem de coliformes) e mantendo essas contaminações em níveis aceitáveis por até 10 dias, sob refrigeração.

ABSTRACT:This research studied the impact of Iceberg lettuce sanitation using ozonized water at 1.0mg L-1 for 1, 2 and 3 minutes in the vegetable shelf-life at 2ºC. It was evaluated populations of aerobic mesophilic bacteria, EnterobacterIaceae, molds/yeasts, total and thermtolerants coliforms, andSalmonellasp. Immediately after 3 minutes of sanitation, decimal reductions of 4.07 (aerobic mesophilic bacteria), 3.36 (EnterobacterIacea), 3.2 (molds/yeasts), 2.18 (total coliforms) and 2.18 (thermtolerants coliforms) were reached. Salmonellasp. was not founded at any evaluated condition. Additionally to the initial reduction, the ozonization improved the lettuce stability during its shelf-life, increasing the delay for microbial growth (from zero to four days) and reducing the microbial growth rate. It occurred especially when sanitation with ozone was carried for 3 minutes of contact. The results showed that the Iceberg lettuce sanitized with ozonated water meets the Brazilian law during the evaluated period, reducing lettuce initial load (that was initially unsafe due to high count of coliforms) and keeping this contamination acceptable for 10 days under refrigeration.

Desempenho produtivo de cultivares de alface americana na estação seca da Amazônia central / Productivity performance in cultivars of crisphead lettuce in the dry season of central Amazonia

Na Amazônia a base da exploração comercial de olericolas é o reconhecimento de cultivares e/ou variedades que evidenciem melhor adaptabilidade para as condições edafoclimaticas locais, associados aos níveis de produtividade comercial em função do sistema de cultivo adotado. Neste sentido, o trabalho teve o objetivo de avaliar a variabilidade morfológica, qualidade e a produtividade entre cultivares de alface tipo americana, cultivadas a campo, em canteiros na presença e ausência de mulching orgânico, no período de estação seca da Amazônia central, estabelecendo-se um experimento no município de Presidente Figueiredo ­ AM. O delineamento experimental utilizado foi blocos ao acaso em esquema fatorial constituídos por 2 preparos de canteiro x 19 cultivares de alface americana, com quatro repetições. Os componentes avaliados foram; estabilidade morfológica; sanidade das plantas; matéria fresca comercial, diâmetro da cabeça comercial, altura das plantas, numero de folhas, comprimento do caule e estimativa da produtividade comercial Kg ha-1. O teste F (p<0,05) detectou diferenças significativas entre o fator correspondente as cultivares, e na interação apenas para sanidade, matéria fresca comercial, numero de folhas e comprimento do caule. Com exceção da estabilidade morfológica, no agrupamento das medias pelo teste Scott-Knott 5 % detectou-se diferença significativa para todas as características avaliadas entre as cultivares. As cultivares Gloriosa, Havassu, Ironwood, Kaiser e Winslon estabeleceram-se mais estáveis na formação de cabeças com melhores resultados agronômicos sobre as características avaliadas para as condições fitotécnicas e edafoclimaticas presentes neste ensaio.

In Amazon the exploration base commercial of vegetable crops is recognition of cultivars and / or varieties that show better adaptability to local conditions, associated with the levels of productivity commercial depending on the crop system. In this sense, the work aimed to evaluate the morphological stability, quality and productivity among cultivars crisphead lettuce, cultivated in seedbeds in the presence and absence of organic mulching, during the dry season in central Amazonia, stabilizing an experiment in municipality of Presidente Figueiredo - AM. The experimental design was a randomized block design in a factorial design consisting of 2 preparations of seedbeds x 19 cultivars of lettuce, with four replications. The components evaluated were; morphological variability; sanity of plants; the fresh materia commercial; commercial head diameter; plant height; number of leaves; stem length and estimated marketable yield kg ha-1. The F test (p <0.05) revealed significant differences the factor corresponding between cultivars and the interaction only for sanity, fresh commercial mass, leaves number and stem length. With the exception of morphological variation in the grouping of averages by the Scott-Knott test at 5 % significant difference was detected for all traits among cultivars. The cultivars; Gloriosa, Havassu, Ironwood, Kaiser and Winslon establish more stable to form heads with better results on agronomic characteristics evaluated for soil and parameters climatic in conditions gifts in this essay.

Allelopathy of Bidens sulphurea L. aqueous extracts on lettuce development / Alelopatia de extratos aquosos de Bidens sulphureaL. no desenvolvimento de alface

ABSTRACT Allelochemical compounds are present in tissues of different plants` parts and also in other organisms, being released into the environment and thus affecting plants development. There is evidence that secondary metabolites produced by weeds may exhibit several allelopathic effects. This study aimed to evaluate allelopathic activity based on the interaction of aqueous extracts preparations and their concentrations obtained from Bidens sulphurea (Cav.) Sch. Bip. leaves on germination and seedlings development of Lactuca sativa L. cv. Grand rapids (lettuce). The extracts were obtained from fresh leaves and prepared by infusion, decoction, leaching and grinding methods, at concentrations of 0, 7.5, 15, 22.5 and 30%, with four replications with 25 lettuce seeds. Seven days after the percentages of abnormal seedlings and germination, shoot and root length (cm) were evaluated, while germination speed index (GSI) was daily determined and calculated. The experiment was completely randomized in a 4x5 factorial design, with four extract preparation methods and 5 concentrations. It was found out that the B. sulphurea aqueous extracts did not affect the germination and abnormal seedling development percentages in lettuce seeds. The aqueous extracts and their concentrations showed allelopathic effect for GSI, shoot and root length variables, despite their methods of preparation. This effect is not only inhibitory, but in some cases it was also stimulatory.

RESUMO Os aleloquímicos são compostos que estão presentes nos tecidos de diferentes partes das plantas e outros organismos, são liberados no ambiente e atuam no desenvolvimento das mesmas. Existem evidências de que os metabólitos secundários produzidos por plantas invasoras podem apresentar uma variedade de efeitos alelopáticos. O presente estudo objetivou avaliar a atividade alelopática através de interação das formas de preparo dos extratos aquosos e suas concentrações obtidas de folhas de Bidens sulphurea (Cav.) Sch. Bip. sobre a germinação e o desenvolvimento de plântulas de Lactuca sativa L. cv. Grand rapids (alface). Os extratos foram obtidos de folhas frescas e preparados sob a forma de infusão, decocção, maceração estática e trituração, nas concentrações de 0; 7,5; 15; 22,5 e 30%, com quatro repetições com 25 sementes de alface. Após sete dias foi avaliado a porcentagem de germinação e plântulas anormais, comprimento da parte aérea e raiz (cm), sendo diariamente as sementes avaliadas para o calculo do índice de velocidade de germinação (IVG). O delineamento experimental foi inteiramente casualizado, organizado em esquema fatorial 4x5, com 4 formas de preparo dos extratos e 5 concentrações. Foi possível constatar que os extratos aquosos de B. sulphurea não influenciaram o percentual de germinação e formação de plântulas anormais em sementes de alface. As diferentes formas de obtenção dos extratos aquosos e suas concentrações apresentaram efeito alelopático para as variáveis IVG, crescimento da parte aérea e comprimento da raiz não sendo o efeito somente inibitório, mas em alguns casos também de estímulo.

Efeito alelopático e análise dos rótulos de garrafadas comercializadas no Mercado Municipal de Montes Claros – MG / Allelopathic effect and analysis of bottle labels commercialized in the municipal market of Montes Claros – MG

RESUMO O presente estudo teve como objetivo analisar o efeito alelopático e o rótulo dos produtos vegetais contidos nas garrafadas comercializadas no mercado municipal de Montes Claros - MG. Adquiriram-se oito garrafadas que foram utilizadas para tratar, cada uma, 20 sementes de alface (Lactuca sativa L.) dispostas em placas de Petri sobre papel saturado com 4mL do conteúdo de cada garrafada em 04 concentrações: 12,5; 25; 50; e 75%. O controle positivo foi realizado com solução de sulfato de zinco a 1%, além dos controles: água mineral, água da torneira, e água destilada. As placas de Petri foram lacradas com filme plástico, cobertas com saco plástico e incubadas em escuro por sete dias à temperatura média de 27,2°C e na umidade média de 54%. Após 7 dias, mediu-se o comprimento da radícula e do hipocótilo (mm) de cada uma das plântulas e quantificou-se o número de sementes que germinaram. Os dados foram submetidos à análise de variância pelo software Sisvar, sendo os resultados comparados pelo Teste Scott-Knott ao nível nominal de 5%. Os resultados do teste de germinação indicaram que houve efeito significativo das garrafadas sobre a germinação das sementes de Lactuca sativa L., onde o percentual de germinação das sementes foi inversamente proporcional ao aumento da concentração das garrafadas. Portanto, observou-se que as garrafadas apresentaram potencial alelopático ao inibirem a germinação das sementes de alface.

ABSTRACT This study aimed to analyze the allelopathic effect and label of plant products put in bottles commercialized in the municipal market of Montes Claros - MG. Eight bottles were employed to treat, each one, 20 lettuce seeds (Lactuca sativa L.) placed at Petri plaques over saturated paper with 4mL of the content of each bottle in 04 concentrations of 12.5; 25; 50; 75% for each bottle, 1% of zinc sulfate solution (positive control) and 3 negative control groups (containing mineral water, tap water and distilled water). The Petri plaques were sealed with plastic film, covered with plastic bag and incubated in the dark for seven days at an average temperature of 27.2°C and average humidity of 54%. After 7 days, it was measured the length of the radicle and the hypocotyl (mm) of each one of the seedlings and the number of seeds that germinated was quantified. The data were submitted to analysis of variance by Sisvar software and the results were compared by Scot-Knott Test at a nominal level of 5%. The results of the germination test indicated that there was a significant impact of the bottles in the germination of the lactuca sativa L. seeds, where the percentage of seeds germination was inversely proportional to the concentration increase in the analyzed bottles. Therefore, it has been observed that the bottles presented allelopathic potential when they inhibited the germination of lettuce seeds.