Peruzzi E.,CNR Institute of Ecosystem Study |
Masciandaro G.,CNR Institute of Ecosystem Study |
Macci C.,CNR Institute of Ecosystem Study |
Doni S.,CNR Institute of Ecosystem Study |
And 3 more authors.
The presence of heavy metals in sludge stabilized in a reed bed system may affect its use for agricultural purposes. However, the environmental impact of sludge depends on the availability and phytotoxicity of these heavy metals. The aim of this research was to determine the effectiveness of a reed bed (Phragmites australis) sludge treatment system in two urban wastewater treatment plants in Italy after a three-year period of operation: (i) by estimating the process of sludge stabilization, following conventional and nonconventional parameters related to the evolution of organic matter quality (water soluble carbon, dehydrogenase activity, pyrolytic fragments); (ii) by following the heavy metal bioavailability in the sludge through their fractionation. For heavy metal fractionation, the Community Bureau of Reference (BCR) was followed. The results showed that there was mineralization and stabilization of sludge over time, suggested by the decrease of about 35% in water soluble carbon and of about 60-80% of dehydrogenase activity. Moreover, significant values of benzene (17%), toluene (31%) and phenol (9%) were found at the end of experimentation in both treatment wetlands, highlighting the re-synthesis of humic-like matter. The results also showed that the content of heavy metals after 30 months was associated with the less mobile fractions of the sludge (more than 60% of total heavy metal content for almost metal), in particular, the fraction linked to the organic matter. © 2010 Elsevier B.V. Source
Rangel-Fajardo Ma.,Colegio de Mexico |
Delgado-Alvarado A.,COLPOS |
Cordova-Tellez L.,Colegio de Mexico |
Zavaletamancera H.A.,Institute Recursos Geneticos y Productividad |
And 3 more authors.
Seed Science and Technology
The main characteristic of recalcitrant seeds is their sensitivity to desiccation, but this sensitivity may vary, depending on genetic and environmental factors, and physiological and biochemical parameters, such as the presence of oligosaccharides of the storage tissue. In this study, tolerance of different cacao genotypes to desiccation was assessed and related to the concentrations of oligosaccharides in their seeds. Fruits of Pound 7 (Forastero), UF668 (Trinitario) and Carmelo (Criollo) were collected from a field plantation of the National Institute of Research in Forestry, Agriculture and Livestock, state of Tabasco, Mexico at 5, 6 and 7 months after flowering (maf). The seeds were dried to 300 g H2O kg-1 fw, and seeds recently extracted from fruits (646 g H2O·kg -1 fw) were used as controls. Sensitivity to desiccation was measured as seed germination (%) and raffinose, stachyose, sucrose, glucose, fructose, arabinose, sorbitol, galactose and mannitol were quantified in the embryonic axes and cotyledons using high precision liquid chromatography. Initial germination was 93%, which decreased 50% on average at 300 g H 2O·kg-1 fw. The proportions of raffinose: sucrose differed; the genotypes UF668 and Pound 7, and seeds from the second harvest (six maf) had higher proportions of 0.25, 0.22 and 0.28 respectively, which were directly related to higher germination. We conclude that the proportion of raffinose: sucrose has a positive influence in sensitivity to desiccation. Source
Bianchi V.,University of Pisa |
Peruzzi E.,CNR Institute of Neuroscience |
Masciandaro G.,CNR Institute of Neuroscience |
Ceccanti B.,CNR Institute of Neuroscience |
And 2 more authors.
The aim of this study is to investigate the efficiency of a reed bed pilot system planted with macrophytes (Phragmites australis) in the stabilisation and dewatering of sludge. The water content of sludge was positively correlated with the biochemical activity (i.e. dehydrogenase activity (DH-ase) and respiration rate) under a wide range of redox conditions (aerobic-anaerobic). Mineralization processes seemed to be uninfluenced by seasonal changing. The metabolic index given by the ratio DH-ase/WSC increased with time from 0.007 to 0.02, implying that sludge organic matter mineralization was approaching maximum efficiency. Aerobic mineralization processes were quickly activated, as shown by the production of ammonia at 3. days and nitrate at 15. days. Nitrates conditioned the redox potential of sludge to relatively high values: from +50 to +150. mV in summer and +10 to +100. mV in winter. The positive redox potentials supported the organic carbon respiration because nitrates function as electron acceptors in the absence or scarcity of free atmospheric oxygen in the deeper layers. All these factors allow the system to (i) operate longer, with high loads applications of sludge and in any climate conditions, thereby making feasible onsite sludge stabilisation and thickening, and (ii) avoid frequent sludge transportation outside the wastewater treatment plant. © 2010 Elsevier B.V. Source
Gutierrez L.,University of the Republic of Uruguay |
German S.,National Agricultural Research Institute INIA |
Pereyra S.,National Agricultural Research Institute INIA |
Hayes P.M.,Oregon State University |
And 16 more authors.
Theoretical and Applied Genetics
Abstract: Diseases represent a major constraint for barley (Hordeum vulgare L.) production in Latin America. Spot blotch (caused by Cochliobolus sativus), stripe rust (caused by Puccinia striiformis f.sp. hordei) and leaf rust (caused by Puccinia hordei) are three of the most important diseases that affect the crop in the region. Since fungicide application is not an economically or environmentally sound solution, the development of durably resistant varieties is a priority for breeding programs. Therefore, new resistance sources are needed. The objective of this work was to detect genomic regions associated with field level plant resistance to spot blotch, stripe rust, and leaf rust in Latin American germplasm. Disease severities measured in multi-environment trials across the Americas and 1,096 SNPs in a population of 360 genotypes were used to identify genomic regions associated with disease resistance. Optimized experimental design and spatial modeling were used in each trial to estimate genotypic means. Genome-Wide Association Mapping (GWAS) in each environment was used to detect Quantitative Trait Loci (QTL). All significant environment-specific QTL were subsequently included in a multi-environment-multi-QTL (MEMQ) model. Geographical origin and inflorescence type were the main determinants of population structure. Spot blotch severity was low to intermediate while leaf and stripe rust severity was high in all environments. Mega-environments were defined by locations for spot blotch and leaf rust. Significant marker-trait associations for spot blotch (9 QTL), leaf (6 QTL) and stripe rust (7 QTL) and both global and environment-specific QTL were detected that will be useful for future breeding efforts.Key message: Multi-environment multi-QTL mixed models were used in a GWAS context to identify QTL for disease resistance. The use of mega-environments aided the interpretation of environment-specific and general QTL. © 2014, Springer-Verlag Berlin Heidelberg. Source
Poblano E.S.,National Autonomous University of Mexico |
Hahn F.F.,National Autonomous University of Mexico |
American Society of Agricultural and Biological Engineers Annual International Meeting 2013, ASABE 2013
Roselle is a flower that is harvested by hand in many places of Mexico. Many machines have been implemented with electric and gasoline motors and they have in common the use of four rollers for pulling the branches full of roselle flowers. The type of motor presents contamination to the calyxes so now electric equipment is the one used. However, rollers lose their traction when water comes out from the branches. As the machines works continuously for 10 hours daily it does not perform well after the first hours. Four rollers were designed using nylamid and being machined like dented like gears throughout the entire roller. The harvester was evaluated with 6 different varieties and water extracted from the branches felt to the rollers groove resulting in a better traction. Calyx damage of 1% was accounted and no flowers were broken during harvest. Its productivity reached 64 kg per hour for var. Nayarit and 62 kg per hour in var. Sudan. Source