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Cruz-Hipolito H.,University of Cordoba, Spain | Osuna M.D.,Finca la Orden Valdesequera Research Center | Dominguez-Valenzuela J.A.,Chapingo Autonomous University | Espinoza N.,Agricultural Research Institute INIA | De Prado R.,University of Cordoba, Spain
Journal of Agricultural and Food Chemistry | Year: 2011

Whole-plant response of two suspected resistant Avena fatua biotypes from Chile and Mexico to ACCase-inhibiting herbicides [aryloxyphenoxypropionate (APP), cyclohexanedione (CHD), and pinoxaden (PPZ)] and the mechanism behind their resistance were studied. Both dose-response and ACCase enzyme activity assays revealed cross-resistance to the three herbicide families in the biotype from Chile. On the other hand, the wild oat biotype from Mexico exhibited resistance to the APP herbicides and cross-resistance to the CHD herbicides, but no resistance to PPZ. Differences in susceptibility between the two biotypes were unrelated to absorption, translocation, and metabolism of the herbicides. PCR generated fragments of the ACCase CT domain spanning the potential mutations sited in the resistant and susceptible biotypes were sequenced and compared. A point mutation was detected in the aspartic acid triplet at the amino acid position 2078 in the Chilean biotype and in isoleucine at the amino acid position 2041 in the Mexican wild oat biotype, which resulted in a glycine triplet and an asparagine triplet, respectively. On the basis of in vitro assays, the target enzyme (ACCase) in these resistant biotypes contains a herbicide-insensitive form. This is the first reported evidence of resistance to pinoxaden in A. fatua. © 2011 American Chemical Society.


Parras-Alcantara L.,University of Cordoba, Spain | Diaz-Jaimes L.,University of Cordoba, Spain | Diaz-Jaimes L.,Agricultural Research Institute INIA | Lozano-Garcia B.,University of Cordoba, Spain | And 3 more authors.
Catena | Year: 2013

Understanding soil dynamics is essential for making appropriate land management decisions, as soils can affect the carbon content from the atmosphere, emitting large quantities of CO2 or storing carbon. This property is essential for climate change mitigation strategies as agriculture and forestry soil management can affect the carbon cycle. The Mediterranean dehesa (Mediterranean grassland ecosystem with scattered oak trees - grazing system with Quercus ilex spp. ballota) is a silvopastoral system that integrates forestry, agricultural and livestock practices. The dehesa is characterized by the preservation of forest oaks that provide environmental services including carbon capture and storage. This paper shows the relationships between soil properties and soil organic carbon (SOC) in two soil types: Cambisols (CM) and Leptosols (LP), with two management systems: organic farming (OF) for 20years and conventional tillage (CT) in a Mediterranean dehesa of southern Spain without cropping. An analysis of 85 soil profiles was performed in 2009 in Los Pedroches Valley (Cordoba, southern Spain). The SOC stock (SOC-S) was greater in CM (75.64Mgha-1) than in LP (44.01Mgha-1). Physical parameters were the main variables affecting soil development. SOC-S was very similar in OF and CT (CM [74.90Mgha-1-CT; 76.39Mgha-1-OF] and LP [44.77Mgha-1-CT; 43.25Mgha-1-OF]). Data analysis showed that management practices had little effect on SOC storage in the study zone. Significant differences between soil types and management practices were found in SOC content for different horizons. The stratification ratio was >2 in both soils types (CM and LP) and management systems (OF and CT). These results indicate that the soil is of high quality, and that management practices have little influence on SOC-S in Los Pedroches Valley. © 2013 Elsevier B.V.


Parras-Alcantara L.,University of Cordoba, Spain | Diaz-Jaimes L.,University of Cordoba, Spain | Diaz-Jaimes L.,Agricultural Research Institute INIA | Lozano-Garcia B.,University of Cordoba, Spain
Land Degradation and Development | Year: 2015

Soil organic carbon (SOC) is subject to relatively rapid changes. In grasslands soils, the management system influences these changes. Therefore, these soils play a crucial role in climate change mitigation. Current research has developed strategies and methodologies to help us understand their role as a carbon sink. In this study, the SOC and total nitrogen contents and stocks (SOC-S) and their variation with depth were evaluated in annual crop rotations (cereal-fallow). Fifty soil profiles were sampled in the Los Pedroches Valley (southern Spain). This area consists of Mediterranean open rangelands-treeless grasslands with cereal-fallow rotation, under two management systems: long-term (20 years) organic farming (OF) and conventional tillage (CT). The studied soils were Cambisols (CM), Leptosols (LP) and Luvisols (LV). The objective of this research was to determine any management system effects (OF vs CT) on SOC and total nitrogen contents and stocks and their variation with profile depth. It was observed that SOC concentration decreased with depth (Ah-Ap>Bw>C). The SOC concentration was higher in the top soil for all studied soils in OF compared with CT. The highest totals of SOC-S were found in LV-OF (66·01Mgha-1) and the lowest in LP-CT (21·33Mgha-1). Significant differences (p<0·05) between soils types and management practices were found in carbon stocks, increasing the SOC-S in OF compared with that in CT in all studied soils; this increase was 75·25%, 85·73% and 234·88% for CM, LV and LP, respectively. The results indicated that management practices significantly influence SOC-S in the Los Pedroches Valley and, consequently, OF in annual crop rotations (cereal-fallow) is an excellent alternative to CT that increases the SOC content in Mediterranean open rangelands-treeless grasslands environments. © 2013 John Wiley & Sons, Ltd.


Parras-Alcantara L.,University of Cordoba, Spain | Diaz-Jaimes L.,University of Cordoba, Spain | Diaz-Jaimes L.,Agricultural Research Institute INIA | Lozano-Garcia B.,University of Cordoba, Spain
Land Degradation and Development | Year: 2015

Under semiarid climatic conditions, intensive tillage increases soil organic matter losses, reduces soil quality, and contributes to climate change due to increased CO2 emissions. There is a need for an agricultural management increasing soil organic matter. This paper presents the organic carbon (OC) and nitrogen (N) stocks, C:N ratio and stratification ratios (SRs) of these properties for olive groves soils under long-term organic farming (OF), and conventional tillage (CT) in Los Pedroches valley, southern Spain. The results show that OF increased C and N stocks. The soil organic carbon (SOC) stock was 73·6Mgha-1 in OF and 54·4Mgha-1 in CT; and the total nitrogen (TN) stock was 7·1Mgha-1 and 5·8Mgha-1 for OF and CT, respectively. In the surface horizon (A: 0-16·9cm in OF and Ap: 0-21·8cm in CT) and Bw horizon (16·9-49·6cm in OF and 21·8-56cm in CT), SOC and TN concentrations and C:N ratios were higher in OF than in CT. Soil properties stratification in depth, expressed as a ratio, indicates the soil quality under different soil management systems. The SR of SOC ranged from 2·2 to 3·1 in OF and from 2·1 to 2·2 in CT. However, only SR2 (defined by Ap-A/C) showed significant differences between CT and OF. The SR of TN showed similar trends to that of the SR of SOC. Organic farming contributes to a better soil quality and to increased carbon sequestration. © 2015 John Wiley & Sons, Ltd.

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