Seeding date influence on camelina seed yield, yield components, and oil content in Chile

Camelina (Camelina sativa L.) was introduced for the first time in Chile in 2008 as a potential feedstock for biodiesel and also as high omega-3-containing seed oil for the salmon feed industry. The objective of this study was to determine the optimum seeding date to maximize camelina seed yield in South Central Chile. The experiment was conducted under dryland conditions in Chillán, El Carmen, Los Angeles, Gorbea, and Osorno in 2008 and in Chillán and Los Angeles in 2009. The experimental design was a RCB with a split-plot arrangement with four replicates, where the main plot was the seeding date (five dates) and the sub-plot the spring type cultivars (Gold of Pleasure, Suneson, and Blaine Creek). Seeding dates at each environment were targeted to 30 April, 15 May, 30 May, 30 June, and 30 July of 2008 and 2009. The combined analysis of variance indicated no cultivar main effect or interactions with cultivar. The date by environment interaction was significant for seed yield. There were no seed yield differences among seeding dates in Chillán and El Carmen. The first three seeding dates were the highest yielding in Los Angeles and Osorno, and only the first seeding date was significantly higher in seed yield in Gorbea. Highest seed yield at Los Angeles, Gorbea, and Osorno were 1995, 1310, and 2314 kg ha⁻¹. Seed oil content was not different among seeding dates in Chillán and El Carmen. Highest seed oil content occurred at Osorno and Gorbea on the first three seeding dates and ranged from 420 to 457 g kg⁻¹. Spring camelina cultivars are well adapted to South Central Chile as a winter annual crop when seeded before 15 May except in Osorno when seeded before 30 May. No disease or insectpests were observed except for Aster Yellow infestation at Chillán and Los Angeles. Camelina has great potential as an oilseed for biodiesel and as a source of omega-3 for the pharmaceutical industry but markets for it need to be developed locally for camelina to become an option for growers.     

Biodegradability of Disinfectants in Surface Waters from Buenos Aires: Isolation of an Indigenous Strain Able to Degrade and Detoxify Benzalkonium Chloride

Biodegradability of chlorhexidine (CH), triclosan (TC), and benzalkonium chloride (CBA) has been tested in 18 surface water sampling points in the urban area of Buenos Aires. Sampling points were located in both the Reconquista and the Matanza-Riachuelo basins as well as in the La Plata River. High tolerance to the three disinfectants was found and indigenous strains capable of degrading CBA and TC were isolated. Neither tolerance nor biodegradation were correlated with sewage pollution. A strain that degrades CBA was identified as belonging to the genus Pseudomonas using the API20NE system and 16SRNA sequencing. In batch assays, the strain was capable of degrading 100, 200, and up to 500 mg L^?1 of CBA in 10, 25, and 46 h respectively with specific growth rates (μ) of 0.56, 0.30, and 0.14 h^?1. The efficiency of the process was between 99.5–98.0% in terms of compound removal and between 93.8–89.1% in terms of chemical oxygen demand (COD). The detoxification of the compound as a result of the biodegradation was assessed using Pseudokirchneriella subcapitata, Vibrio fischeri, and Lactuca sativa as test organisms.     

A review on <Emphasis Type="Italic">Trioza erytreae</Emphasis> (African citrus psyllid), now in mainland Europe,and its potential risk as vector of huanglongbing (HLB) in citrus

The African citrus psyllid (AfCP), Trioza erytreae (Del Guercio) (Hemiptera, Triozidae), recently has been found in northwestern Iberian Peninsula (Spain and Portugal). The insect is an important citrus pest because it transmits the phloem-limited bacteria Candidatus liberibacter spp., the causal agents of huanglongbing (HLB), the most devastating disease affecting citrus. The bacteria can be acquired by both AfCP nymphs and adults, but only adults can spread the pathogen. HLB has been detected neither in the Iberian Peninsula nor in Madeira and the Canary Islands, where the psyllid was recorded more than a decade ago. In the latter European islands, the eradication programmes of AfCP failed. Chemical-based control strategies are costly, could trigger increases of other pests and may have negative impact on the environment. The adoption of rigorous quarantine measures is extremely important for areas free of the psyllid. These measures likely represent the most effective prevention strategies for psyllid containment, because the geographic expansion of psyllids in citrus is mainly due to human activities, especially by the transport of plants and freshly harvested fruits from infested to uninfested areas. Many natural enemies may contribute to the reduction of its populations and consequent spread; hence, conservation biological control should be emphasised, especially in areas where the psyllid is not abundant. Classical biological control programmes should also be implemented in HLB-free areas by introducing effective AfCP parasitoids. In areas where HLB is detected, biological control is difficult to apply, and a rigorous chemical control program targeting the psyllid could complement this strategy. This report is an updated review of AfCP and strategies for its control in anticipation of its possible further spread in Europe and the Mediterranean Basin.     

Influence of colored plastic mulch on soil temperature,growth, nutrimental status,and yield of bell pepper under shade house conditions

The aim of this study was to determine if plastic mulch films may have positive effects on bell pepper plants grown under shade house conditions. The experimental design was split-plot, where large plots contained four plastic mulch films (black, aluminum, silver, and white) compared to bare soil and small plots contained two bell pepper cultivars. Plant shoot dry weight was higher in plastic mulch treatments than in bare soil. The net photosynthesis rate in the cultivar SWG-46 exceeded in net photosynthesis with respect to the cultivar SWG-42 in one of three sampling dates. Nutrients in leaf showed a similar behavior in plastic mulch treatments than the control but the total content of nitrogen (N), potassium (K), and sulfur (S) was increased. The total yield was higher in black plastic mulch than in the other plastic mulch colors and lowest in the control.     

Short-term effects of overstory reduction and slash mulching on ground vegetation in a Mediterranean Aleppo pine woodland

The short-term effects of forest overstory reduction and slash mulching on ground vegetation were analysed in a Mediterranean Aleppo pine reforested woodland on degraded agricultural land in south-east Spain. This sort of practice is becoming common in the Mediterranean basin to guard against forest fires, but very few attempts have been made to analyse its effect upon biodiversity. The data concerning floristic richness and above-ground biomass of species were measured as dependent variables in 0.5 × 0.5 m quadrats in an overstory reduction versus control area (treatment factor) during the spring of 2006. The data were analysed by ANCOVA, in which slash-mulch weight was introduced as covariate. Relationships between dependent variables and slash-mulch weight were examined using linear regression, and variations in floristic composition were ascertained by means of principal component analysis (PCA). A total of 32 ruderal herbaceous species were recorded, none of which was exotic. In spite of some methodological constraints (i.e. low number of samples and data from a non-replicated case study), the results of our study point to the conclusion that most of these species were found more frequently in the overstory-reduction treatment compared to the control area, and that only a few species clearly preferred the control treatment. In general, overstory reduction led to a significant increase both in floristic richness and above-ground biomass. Slash mulching, on the other hand, encouraged the appearance of a greater quantity of above-ground biomass (in different ways depending upon treatment), although species richness did not improve, even to the extent of declining in the control area. On the basis of our findings, overstory reduction seems to increase species richness and productivity in dense Mediterranean afforestations on degraded agricultural land, at least in the short-term. Large quantities of mulch accompanied by high tree density would seem not to favour species richness.     

European Eel Sperm Diluent for Short‐term Storage

The sperm of European eel shows a high density and the time of spermatozoa motility is very short after activation with sea water. These characteristics make difficult the sperm handling and its quality assessment. Several diluents were previously described for the Japanese eel obtaining over 3 weeks’ conservation times under refrigeration, but they rendered bad results in the European species. In the present study, several diluents were developed taking as basis the P1 medium, and using different dilution ratios (1 : 50, 1 : 100) and two pH (6.5, 8.5). The effect of the addition of bovine serum albumin (BSA, 2% w/v) was also evaluated. At 24 h, undiluted samples already showed significant lower motility and viability than sperm samples diluted in the different media. The results for diluents with pH 6.5 and 8.5 were different. Spermatozoa diluted in media at pH 6.5 cannot be activated at 24 h, while samples diluted in the diluents with pH 8.5 and added with BSA did not show significant differences with respect to the fresh sperm motility until 48 h. The viability (percentage of alive cells) did not show differences until 1 week, independent of the dilution ratio. After 1 week, the motility was approximately 30% in the media containing BSA, which presented no differences for head size of the spermatozoa (perimeter and area) until 72 h and 1 week, respectively. In conclusion, the combination of one medium having similar physico‐chemical characteristics to the seminal plasma, including pH 8.5, and supplemented with BSA can be used in different dilution ratios for the sperm’s short‐term storage, preserving its motility capacity.     

Molecular sequence data of Thecaphora frezii affecting peanut crops in Argentina

In Argentina, Thecaphora frezii is the causal agent of peanut smut, causing severe yield losses in peanut growing areas. In this work sequence data of the large ribosomal subunit (28S rDNA) of four T. frezii specimens from different production regions are provided. A fragment of about 650 bp was amplified by PCR from each of the isolates analyzed. The analysis of the sequences demonstrated 100 % identity among the four specimens and 92–96.3 % identity with sequences of other species of Thecaphora. This is the first study on molecular sequences of this pathogen.     

Restoration and Rehabilitation of Mixed Espinales in Central Chile: 10-Year Report and Appraisal

A synthesis of progress achieved thus far is provided for a 10 - year research and development program aimed at the ecological and economic rehabilitation of agroecosystems in the unirrigated portions of the central valley of Chile's Mediterranean climate region. We review our data on (1) revised management techniques aimed at restoring the gross superstructure and former levels of diversity and productivity of a mixed espinales formation; (2) selection and utilization of ecotypes of the naturalized annual Medicago polymorpha L. and the N2-fixing microsymbiont Rhizobium meliloti, for gradual improvement of espinal soil fertility; and (3) studies of the outstandingly well adapted and fast growing Canary Island tree Chamaecytisus proliferus (L. fil.) Link ssp. palmensis (Christ) Kunkel (Tagasaste), which along with about three dozen other woody nitrogen - fixing legume and several nonlegume multipurpose trees, was considered to be of potential value for deep soil layer rehabilitation combined with economic improvements. In all these subprograms, efforts were made to identify techniques or organisms that could provide short-term benefits to landowners, especially in the form of wood, fuelwood, or forage for livestock. We also consider various approaches to be added to the program over the next decade, especially in view of the overarching goal of reintegrating fragmented landscapes and combining restoration with rehabilitation and reallocation at this spatial scale.     

Resistance to the Whitefly Aleurotrachelus socialis (Hemiptera: Aleyrodidae) and SSR Marker Identification in Advanced Populations of the Hybrid Manihot esculenta subsp. Manihot flabellifolia

Genes resistant to Aleurotrachelus socialis were transferred to the F₁ from the interspecific hybrid wild species of Manihot flabellifolia to M. esculenta and two advanced generations of backcrosses (BC₁ and BC₂). We characterized the resistance of A. socialis transferred to BC₂ parents (CW67-160, CW67-130, CW67-44), MTAI-8 (BC₁), resistant (CMB9B-73) and susceptible (CMB9B-104) genotypes from contrasting pools, and resistant (MEcu-72) and susceptible (CMC-40) genotypes. Whitefly demography and biology were evaluated. SSR molecular markers associated with a phenotypic response of plant resistance were detected in segregating populations (BC₂). Results showed that although female survival time was similar on all hosts, the lowest averages of longevity, fecundity and oviposition rate were observed in the resistant control MEcu-72, only being significantly similar to the parent CW67-130. When the BC₁ and BC₂ populations were compared, it was found that A. socialis fecundity was eight times lower on CMB9B-73 progeny than on CW67-130, expressing the highest levels of resistance to the whitefly. Ten genotypes of CMB9A and CMB9B family had the best segregation. A total of 486 microsatellite primers were evaluated using bulked segregant analysis (BSA), 11 showed polymorphism between the contrasting pools and only one showed significant differences between resistant and susceptible individuals. In conclusion, fecundity was the parameter that impacted most on the intrinsic rate of A. socialis population growth.