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Effect of Different Rootstocks on Growth, Chlorophyll a Fluorescence and Mineral Composition of Two Grafted Scions of Tomato
No full textTwo tomato scions (cvs. ‘Raf’ and ‘Gorety’) were grafted on three different rootstocks: S. torvum, ‘Beaufort’ (Lycopersicum esculentum × Lycopersicum hirsutum) and intermediate grafting of eggplant ‘Cristal’ between tomato and S. torvum (double graft). Plants were grown in Mediterranean greenhouse conditions. The response to grafting was measured through growth parameters, Fv/Fm and leaf macronutrients analysis, and it was compared with non-grafted plants. The scions grafted on S. torvum in simple and double graft showed lower fresh and dry weight of leaves, number of commercial fruits, plant height, Fv/Fm and decreased their capacity to absorb several nutrients resulting in a lower mineral concentration in scions leaves, as a result of a thickened graft union. On the other hand, both scions showed a good response when grafted on the rootstock ‘Beaufort’, with which growth parameters, yield and photosynthetic capacity were similar to non-grafted plants
The effect of sodium bicarbonate on plant performance and iron acquisition system of FA-5 (Forner-Alcaide 5) citrus seedlings
No full textThis work studies the effect of bicarbonate on plant performance and the iron acquisition system of Forner-Alcaide 5 (FA-5) seedlings, a citrus genotype known for its tolerance to calcareous soils. Plants were irrigated for 6 weeks with or without 10 mM NaHCO3. Treatment significantly decreased shoot growth, photosynthetic levels and iron concentration in shoots and roots. o,o-(57)FeEDDHA experiments indicated that Fe-57 uptake by roots was inhibited in treated plants. Moreover, those seedlings accumulated more Fe-57 in roots, and enhanced mRNA accumulation of ferric reductase genes FRO1 and FRO2 and FC-R activity in roots. H+-ATPase activity and HA1 gene expression were also increased, while HA2 was not affected. In addition, expression of the iron transporter gene IRT1 was increased, while IRT2 was not significantly affected. Finally, according to PEPC enzymatic activity, PEPC1 gene expression was higher in treated roots. In conclusion, it appears that bicarbonate prevents medium acidification by roots, thus reducing Fe2+ uptake. Accordingly, Fe deficiency enhanced the expression of some genes related with the Fe acquisition system (IRT1, FRO1, FRO2, HA1 and PEPC1) and the activity of the corresponding enzymes, which appear to constitute an adaptive mechanism of FA-5 in these soils
dUTPases, the unexplored family of signalling molecules
No full textDeciphering the molecular mechanisms that control relevant cellular processes is of utmost importance to understand how viruses, prokaryotic and eukaryotic cells work. The diversity of living organisms suggests that there are novel regulators still to be discovered, which may uncover new regulatory paradigms. dUTPases (Duts) are assumed to be ubiquitous enzymes regulating cellular dUTP levels to prevent misincorporation of uracil into DNA. Recently however, Duts have been involved in the control of several relevant cellular processes, including transfer of mobile genetic elements, regulation of the immune system, autoimmunity or apoptosis, suggesting that they perform regulatory functions. This review aims at investigating the unexplored impact of Duts as novel signalling molecules
Phenolic composition, organic acids, sugars, vitamin C and antioxidant activity in the juice of two new triploid late-season mandarins
No full textFruit juices of 'Safor' [(Citrus clementina x Citrus tangerina) x (Citrus unshiu x Citrus nobilis)] and 'Garbi' [(Citrus clementina x Citrus tangerina) x (Citrus reticulata x Citrus sinensis)] mandarins were analyzed in order to compare the main nutritional components of fruit to those of their respective parents. Vitamin C, total phenolic, flavonoid, phenolic acid, organic acid and sugar contents as well as juice yield, total soluble solids (TSS), titratable acidity (TA) and maturity index (TSS/TA) were determined. Antioxidant activity was measured by two methods, the free radical-scavenging (DPPH) and ferric reducing/antioxidant power (FRAP) tests. 'Safor' and 'Garbi' hybrids showed both high quality parameters of juice at maturity which makes them good for fresh consumption. The results of this study show that 'Safor' fruit exhibited high levels of vitamin c, total phenolics, flavonoids and antioxidant activity. In addition, the organic acid contents in the fruit juices of these new triploid mandarins were superior than those of their parents. Generally, 'Safor' and 'Garbi' mandarins displayed similar contents of health-promoting components as those of their parents. (C) 2012 Elsevier Ltd. All rights reserved
Prospects for the biological control of Tuta absoluta in tomatoes of the Mediterranean basin
No full textSince its detection in the Mediterranean basin at the end of 2006 and later in other European countries, the South American tomato pinworm, Tuta absoluta (Meyrick), has become a serious threat to tomato crops. In newly infested areas, it is especially problematic during the first years of its presence. Nevertheless, after 23 years, the incidence of T. absoluta has become less severe in certain areas. There are several factors contributing to this decline, such as the increase in growers' knowledge of pest behaviour and biology and the correct application of integrated pest control strategies. The impact of opportunistic native natural enemies (fortuitous biological control) should be considered as one of the key factors in this decline. In this review, available information on indigenous natural enemies is updated, and the current pest management approaches used against T. absoluta are addressed. Finally, future scenarios for biological control of this pest are discussed. Copyright (c) 2012 Society of Chemical Industr
Life history parameters and scale-cover surface area of Aonidiella aurantii are altered in a mating disruption environment: implications for biological control
Get PDFBACKGROUND: In recent years, environmentally safe measures to control the California red scale (CRS), Aonidiella aurantii (Maskell), have been successfully implemented. These measures include mating disruption (MD) and biological control. The goal of this study was to examine the effect of high concentrations of the CRS sex pheromone on its life history parameters and scale-cover surface area under controlled laboratory conditions. RESULTS: The developmental time of both males and females of CRS increased with exposure to airborne pheromone. MD had an effect on both the total number of progeny and on the crawler production period for females. Accordingly, demographic parameters such as net fecundity (R0) and intrinsic rate of increase (rm) were significantly lower in the pheromone-treated populations. The largest scale-cover surface areas were observed in the CRS reared in the pheromone environment. CONCLUSION: A clear influence of airborne pheromone on the biology of CRS has been demonstrated. In addition to the classical mating disruption benefits of this technique, additional benefits, such as increase in the duration of exposure to natural enemies and increase in size, which benefits some species of parasitoids, have been confirmed. Copyright (c) 2012 Society of Chemical Industr
Comparison of Growth Responses to Auxin 1-Naphthaleneacetic Acid and the Ethylene Precursor 1-Aminocyclopropane-1-Carboxilic Acid in Maize Seedling Root
Get PDFApplication of 1-naphthaleneacetic acid (NAA) or 1-aminocyclopropane-1-carboxilic acid (ACC) to maize roots growing in hydroponic solution inhibited root elongation, and increased radial growth, but the responses to those treatments differed in degree. Auxin was more effective than ACC as an elongation inhibitor and root swelling promoter. Whereas NAA fully inhibited elongation and maintained swelling over 48 h, ACC inhibited elongation partially (50%) and only promoted swelling for 24 h. It is well-known that auxin, like ACC, promotes ethylene production, but similar levels of ethylene production reached by means of NAA or ACC treatments did not elicit the same response, the response being always stronger to NAA than to ACC. These results suggest that the effect of auxin on root growth is not mediated by ethylene. Elongation and swelling of roots appear to be inversely related: usually a reduction in elongation was accompanied by corresponding swelling. However, these two processes showed different sensitivities to growth regulators. After 24 h treatment with 0.5 mu M NAA or 5 mu M ACC, root elongation was inhibited by 90% and 53% respectively, but the same treatments promoted swelling by 187% and 140% respectively. Furthermore, 1 mu M ACC was shown to promote inhibition of root elongation without affecting swelling. The ethylene antagonist STS (silver thiosulfate) did not affect elongation in control or NAAtreated roots, but increased ethylene production and swelling. These results indicate that longitudinal and radial expansion could be independently controlled
Prediction of the soil saturated paste extract salinity from extractable ions, cation exchange capacity, and anion exclusion
No full textProcess-based models could be used to predict the soil saturated extract salinity from extractable ion contents. However, a rigorous validation of such models for this purpose had not been carried out. A process-based model to predict the main inorganic ion composition, electrical conductivity, and pH of the saturated paste extract from extractable ion contents was developed step by step. The model development started from the principle of matter conservation in the soil solution as it concentrates from the 1 : 5 to the saturated paste extract. The need to include new hypotheses in the model was studied through calculation and analysis of standardised differences between measurements and model predictions. Therefore, best estimates of saturation paste extract properties occurred after taking into account the following: (i) free equilibration of the soil solution with the minerals calcite and gypsum under CO2 partial pressure of the saturated paste; (ii) further equilibration of the soil solution with the exchange complex; and (iii) determination of salt contents within the diffuse double layer (DDL) of the soil colloids, i.e. the anion exclusion. The last was necessary because the extracts where the determination of soil extractable anions (1 : 5 extracts), cations, and cation exchange capacity (CEC) were carried out were separated from their suspensions through centrifugation. Therefore, the reliable prediction of soil saturated paste extract salinity demands data on soil extractable ion contents, CEC, and the quantification of salts within the DDL
Cítricos: Cultivo, Poscosecha e Industrialización
No full textLas enfermedades de poscosecha pueden representar hasta pérdidas económicas del 80% en el sector citrícola. Estas pérdidas son muy variables y dependen de múltiples factores: zona de producción, especie y cultivar, edad y condición de los árboles, condiciones climatológicas durante toda la campaña, época y forma de recolección, manejo de los frutos en poscosecha, condiciones de almacenamiento y mercado de destino. Los tratamientos más comunes para el control de estas enfermedades son los fungicidas sintéticos. Sin embargo, la aplicación masiva y continuada durante años de materias activas similares (tiabendazol, imazalil, entre otros.) ha generado graves preocupaciones a los consumidores y a las entidades gubernamentales debidas, entre otros motivos, a la contaminación generada por un exceso de residuos químicos y a la proliferación de cepas patogénicas resistentes. Además, hay un marcado cambio de tendencia en la comercialización de productos
hortofrutícolas hacia los mercados de productos ecológicos u orgánicos y, al mismo tiempo, los mercados ‘tradicionales’ están exigiendo el cumplimiento de criterios propios más restrictivos que los límites máximos de residuos (LMR) establecidos por la legislación. Todo ello ha conducido a la búsqueda de alternativas a los agroquímicos para el control de las enfermedades de poscosecha. En este capítulo se aborda el control mediante estrategias de CINCEP (control integrado no contaminante de enfermedades de poscosecha), que se basan en el conocimiento profundo de la epidemiología de los patógenos y de los factores que determinan su incidencia en precosecha, cosecha y poscosecha para incidir de forma global sobre el problema actuando sobre cada uno de estos factores en el momento adecuado para minimizar las pérdidas económicas. En general, es importante cosechar con el índice de madurez adecuado, siempre con tiempo seco y de forma extremadamente cuidadosa para minimizar heridas en la piel y otros daños físicos. En poscosecha se requieren tratamientos o combinaciones de tratamientos alternativos que, según su naturaleza, pueden ser físicos, químicos de baja toxicidad y biológicos. Entre los tratamientos físicos se destacan el calor (curado, agua caliente), las irradiaciones (luz UV-C) o los choques gaseosos. Los principales
tratamientos químicos alternativos se basan en la aplicación de sustancias naturales (extractos de plantas, aceites esenciales), aditivos alimentarios o recubrimientos comestibles antifúngicos. El control biológico consiste en la aplicación controlada de microorganismos antagónicos a los patógenos