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 [...].

Efecto biofertilizante del preparado: residuos vegetales - bacteria nativa diazótrofa, sobre las variables biométricas en plántulas de Rhapanus sativus / Biofertilizer effect of the prepared from vegetales wastes - diazotroph native bacterium on biometrics variables of Rhapanus sativus seedlings

El uso de bioinoculantes a base de microorganismos con potencial biofertilizante representa una alternativa económicamente viable y de producción limpia para el sector agrícola. El objetivo del presente trabajo fue evaluar el efecto biofertilizante de un preparado elaborado con residuos sólidos vegetales (RSV) procedentes del mercado y la bacteria nativa diazótrofa Azotobacter A15M2G. Se elaboraron biopreparados utilizando diferentes concentraciones de bacteria (106, 107 y 108 UFC) en un medio de cultivo obtenido a partir del 25% p/v de cada uno de los siguientes RSV: Brassica oleracea (repollo), Lactuca sativa (lechuga) y Allium fistulosum (cebollín). Los biopreparados fueron evaluados en plantas de rábano (Rhapanus sativus) en invernadero, utilizando un diseño estadístico completamente al azar de 5 tratamientos con 3 repeticiones: T1, control; T2, semillas pregerminadas tratadas con RSV al 25% p/v; T3, semillas pregerminadas con bioinoculante de 106 UFC; T4, semillas pregerminadas con bioinoculante de 107 UFC; T5, semillas pregerminadas con bioinoculante de 108 UFC. Se evaluó: número de hojas, área foliar, longitud de la planta, longitud de la raíz y peso seco de toda la planta (ensayos por triplicado). Se observó un incremento altamente significativo en peso seco para T5 (0,88 g) y T4 (1,10 g); y diferencias significativas en el área foliar, para los mismos tratamientos, con un valor superior a 2000 cm2. El biopreparado con bacterias nativas y RSV mejoró el crecimiento y desarrollo de las plantas de rábano, pudiéndose dar un valor agregado a estos residuos y de esta manera obtener un biofertilizante potencialmente utilizable en otros cultivos.

The use of bioinoculantes from microorganisms with biofertilizer potential, represents an economically viable alternative and of clean production for the agricultural sector. The aim of this study was to evaluate the effect of biofertilizer preparation obtained from vegetable solid waste (RSV) of the market and the native bacteria Azotobacter A15M2G diazotroph.Biological cultures were prepared using different inoculum concentrations, 106, 107 y 108 UFC in a culture medium obtained from 25% w / v of each of the following substrates: Brassica oleracea (cabbage), Lactuca sativa (lettuce) and Allium fistulosum (chives). The microbial inoculants were evaluated in radish plants (Rhapanus sativus) in greenhouse using a completely randomized design of 5 treatments with 3 replicates: T1, pre-germinated seeds without any treatment; T2, pre-germinated seeds treated with the dye waste vegetables 25% w / v; T3, pre-germinated seeds treated with bacterial concentration bioinoculants to 106 UFC; T4, pre-germinated seeds treated with bacterial concentration bioinoculants to 107 UFC, and T5, pre-germinated seeds treated with bacterial concentration bioinoculants to 108 UFC. Assessed variables were: number of leaves, leaf area, plant length, root length and dry weight of the entire plant (all assays in triplicate). The results showed a highly significant increase in dry weight, for T5 (0.88 g) and T4(1.10 g); and significant differences in leaf area for the same treatments, with a value greater than 2000 cm2, compared to others. The biopreparado from native bacteria and RSV improved the growth and development of the radish plants, being able to give a added value to these residues and to obtain a potentially usable biofertilizer in other cultures.

Lettuce (Lactuca sativa L. ) seed quality evaluation using seed physical attributes, saturated salt accelerated aging and the seed vigour imaging system

High seed quality is essential for optimum stand establishment in lettuce. As a result, it is necessary to have seed vigour tests that permit rapid, objective and accurate evaluation of seed quality. This study evaluated physical and physiological seed quality components of four seed lots of six lettuce varieties obtained from a commercial company. Seeds were evaluated for seedling emergence under greenhouse conditions, standard germination, seed physical aspects, the Saturated Salt Accelerated Aging (SSAA) test and the Seed Vigour Imaging System (SVIS). Results indicated that large-seeded lettuce varieties had higher percentage germination, higher SSAA values, higher SVIS index and more rapid and uniform greenhouse emergence. Black-seeded lettuce varieties possessed higher seed quality and less fungal invasion when evaluated by the SSAA test. The SVIS index significantly correlated with SSAA values and seedling emergence under greenhouse conditions suggesting it can be used as a measure of seed vigour. It is concluded that the SSAA and SVIS tests are practical and accurate determinants of lettuce seed quality and distinguish between high and poor quality lettuce seed lots.

Influencia de las características del sueloen el acogollado de lechugas (Lactuca sativa var. capitata L-4) / Influence of soil characteristic on Lettuce hearted (Lactuca sativa var. capitata L-4)

La lechuga se cultiva extensivamente en el área Mediterránea, y es la provincia de Murcia la que tiene una producción mas elevada, siendo la variedad más exportada la Iceberg, que es la estudiada en este trabajo (Lactuca sativa var. capitata L-4).Al ser el acogollado una de las características agronómicas mas interesantes para esta hortaliza, en este trabajo estudiamos las características del suelo en el fenómeno del acogollado.De acuerdo con las condiciones de cultivo en la zona de Pozoestrecho (Murcia), se toman muestras de (Torriorthent típico) y de material vegetal; concluyendo que el contenido en arcilla del suelo más favorable para el acogollado de la variedad estudiada está comprendido entre el 25-55 por ciento, que corresponde a texturas francas, arcillo-arenosas y arcillo-limosas.Se ha observado que al aumentar la salinidad el acogollado es menor y que los cultivos que se realizan entre Octubre y Mayo necesitan un aporte suplementario de agua (AU)