Effects of biochar on microbial community in bioflocs and gut of Oreochromis niloticus reared in a biofloc system

Aquaculture International - This study investigated the effects of biochar application on the bacterial community structure in bioflocs and intestines of Oreochromis niloticus cultured in a biofloc...     

Monitoring of eucalyptus sprouts control using digital images obtained by unmanned aerial vehicle

This study evaluated the effectiveness of chemical control for eradicating eucalyptus sprouts using images obtained with Unmanned Aerial Vehicle (UAV). The study was carried out in eucalyptus plantations in Itabela, BA, in replanting areas during pre-planting application of herbicide. Aerial images obtained by a UAV were used to evaluate the effectiveness of the herbicide application for sprouts control. After the images were acquired, they were processed to calculate the normalized difference vegetation index (NDVI) and submitted to a supervised classification to quantify the percentage reduction of sprout green matter. The percentage data were submitted to analysis of variance and the means were compared by Tukey test at 5%. The differences, both visual and average percentages were observed only during the evaluation period with no evident effect of the treatments on sprout control. The images provided by the UAV allowed to monitor and identify visually the plots where biomass reduced or increased and to evaluate the effectiveness of chemical control of eucalyptus sprouts, indicating areas where it was nonexistent, partial or total.     

Geographic variation in pheromone component ratio and antennal responses,but not in attraction,to sex pheromones among fall armyworm populations infesting corn in Mexico

The fall armyworm, Spodoptera frugiperda (Lepidoptera: Noctuidae), is one of the most important pests of corn in Latin America. This insect presents two strains with behavioural and genetic differences. In Mexico, both strains are present, and at least two different FAW populations have been reported within the corn-strain. The objective of this study was to gather evidence of whether pheromonal communication varies among different S. frugiperda populations infesting corn in Mexico. First, we investigated any qualitative or quantitative difference in the composition of sex pheromones among populations; second, we studied whether male antennal responses to pheromone components vary among populations; and, finally, we investigated whether males from a region can discriminate between a synthetic pheromone blend characteristic of their region and blends formulated with the ratio of pheromone compounds emitted by females from other populations. Sex pheromone components were sampled by solid-phase microextraction and identified by gas chromatography coupled to mass spectrometry. Females from all populations consistently released three compounds: (Z)-9-tetradecenyl acetate (Z9-14:OAc), (Z)-11-hexadecenyl acetate (Z11-16:OAc) and (Z)-7-dodecenyl acetate (Z7-12:OAc). Our results showed that Z9-14:OAc and Z7-12:OAc evoked the highest and most variable antennal responses among the populations studied compared to Z11-16:OAc. However, males did not discriminate between local pheromone blends and those formulated from other populations in a field test. These results show that although there is geographic variation in the ratio of pheromone components and in the peripheral reception of them, males were not differentially attracted to different pheromone blends in the field.     

PESO: a modelling framework to help improve management strategies for epidemics – application to sharka

The optimization of management strategies for plant diseases is a difficult task because of the complexity and variability of epidemic dynamics. Thanks to their ability to numerically simulate many scenarios, models can be used to estimate epidemiological parameters, assess the effectiveness of different management strategies and optimize them. This article presents the PESO (parameter estimation–simulation–optimization) modelling framework to help improve plant disease management strategies. This framework is based on (i) the characterization of the epidemic dynamics to estimate key epidemiological parameters, (ii) the use of spatially explicit models to simulate epidemic dynamics and disease management, and (iii) the use of numerical optimization methods to identify better management strategies. This approach is generic and can be applied to many diseases. The work presented here focuses on sharka (caused by Plum pox virus), which has a worldwide impact on the Prunus industry, and is associated with huge disease management costs in many countries, especially in France.     

Differential expression of molecular rust resistance components have distinctive profiles in <Emphasis Type="Italic">Coffea arabica</Emphasis> - <Emphasis Type="Italic">Hemileia vastatrix</Emphasis> interactions

Countering the economic hurdle caused by coffee leaf rust disease is most appealing at this time as it has posed a major threat to coffee production around the world. Establishing differential expression profiles at different times following pathogen invasion in both innate and acquired immunities unlocks the molecular components of resistance and susceptibility. Suppression subtractive hybridization (SSH) was used to identify genes differentially over-expressed and repressed during incompatible and compatible interactions between Coffea arabica and Hemileia vastatrix. From 433 clones of expressed sequence tags (ESTs) sequenced, 352 were annotated and categorized of which the proportion of genes expressed during compatible interaction were relatively smaller. The result showed upregulation and downregulation of various genes at 12 and 24 h after pathogen inoculation in both interactions. The use of four different databases in searching for gene homology resulted in different number of similar sequences. BLASTx against EMBL-EBI (European Molecular Biology Laboratory-European Bioinformatics Institute) database being with the maximum (100%) hits for all the annotated sequences. RT-qPCR analysis of seven resistance-signaling genes showed similar expression patterns for most of the genes in both interactions, indicating these genes are involved in basal (non-specific) defense during which immune reactions are similar. Using SSH, we identified different types of resistance related genes that could be used for further studies towards resistant cultivar development. The potential role of some of the resistance related proteins found were also discussed.     

A Hierarchical Perspective to Woody Plant Encroachment for Conservation of Prairie-Chickens

Encroachment of Great Plains grasslands by fire-sensitive woody plants is a large-scale, regional process that fragments grassland landscapes. Using prairie grouse (Tympanuchus spp.) of conservation concern, we apply hierarchy theory to demonstrate how regional processes constrain lower-level processes and reduce the success of local management. For example, fire and grazing management may be locally important to conservation, but the application of fire and grazing disturbances rarely cause irreversible fragmentation of grasslands in the Great Plains. These disturbance processes cause short-term alterations in vegetation conditions that can be positive or negative, but from a long-term perspective fire maintains large tracts of continuous rangelands by limiting woody plant encroachment. Conservation efforts for prairie grouse should be focused on landscape processes that contribute to landscape fragmentation, such as increased dominance of trees or conversion to other land uses. In fact, reliance on local management (e.g., maintaining vegetation structure) to alter prairie grouse vital rates is less important to grouse population persistence given contemporary landscape level changes. Changing grass height, litter depth, or increasing the cover of forbs may impact a few remaining prairie-chickens, but it will not create useable space at a scale relevant to the historic conditions that existed before land conversion and fire suppression.     

Effects of Vermicompost and Vermiwash on Plant,Phenolic Content,and Anti-oxidant Activity of Mexican Pepperleaf (Piper auritum Kunth) Cultivated in Phosphate Rock Potting Media

The aim of this investigation was to determine the effect of vermicompost, vermiwash, and phosphate rock on plant, total phenols, flavonoids, and anti-oxidant activity in Piper auritum Kunth leaves. P. auritum plants were obtained from cuttings and were planted according to the Box-Behnken experimental design with three repetitions at the central point. The factors and levels were vermicompost (10, 20, and 30 g plant^?1), vermiwash (5, 10, and 15 mL plant^?1), and phosphate rock (1, 2, and 3 g plant^?1). Plant growth parameters (plant height, stem diameter, leaves number) and chlorophyll content were measured 1 month after treatment applications. Total phenols, total flavonoids, and 1,1-diphenyl-2-picryl-hydrazyl radical scavenging activity was measured after 4 months. Vermicompost, vermiwash, and phosphate rock had no statistically significant effect on plant growth. Plant height, stem diameter, leaves number, chlorophyll, innermost number, fresh weight stem, fresh weight leaves, fresh weight root, dry weight stem, dry weight leaves, and dry weight root were not different among treatments. Total phenolic compounds were statistically affected for both vermiwash and phosphoric rock (p < 0.05) and the anti-oxidant activity decreased by vermicompost addition. The application of 15 mL plant^?1 vermiwash, 1 g phosphate rock, and 20 g vermicompost plant^?1 increased the total phenol content.     

Sensitivity of Soil P Availability Tests to Ca-P in Oxisols

We assessed the sensitivity of mixed exchange resin (MER) and Mehlich-3 (M3) to calcium-bound phosphate (Ca-P) in Oxisols. These methods were compared with Mehlich-1 (M1) and anion exchange resin (AER), which have high and low sensitivity, respectively, to this soil P form. We used maize (Zea mays L.) as a test plant. Three samples from two Oxisols were treated with five ratios of Triple Superphosphate—TS and Bayóvar Phosphate Rock—BPR (0 + 100; 25 + 75, 50 + 50, 75 + 25 and 100 + 0% TS + BPR). The MER extracted more P than AER and M3 at the highest BPR:TS ratios (high Ca-P) and similar quantities at the higher TS:BPR ratios (low Ca-P) for two soil samples. Unlike M1-extracted P, M3-P, AER-P, and MER-P positively correlated with maize dry matter production and P uptake. Mehlich-3 and MER were suitable to assess P availability in high Ca-P Oxisols.     

Foliar application of calcium and kinetin on soybean at reproductive stage

We characterized the pollination and fecundation times in soybean flowers and evaluated the effects of kinetin and calcium applications on physiological and productive traits of soybean plants during the reproductive stage. The anatomical study of flowers of eight soybean cultivars showed that fecundation occurred in closed flowers with visible petals, which presented embryo in the first cell divisions. These results indicate that fertilizers and growth regulation applications should be performed before flower opening, which is different from the current recommendation. Foliar applications of kinetin and calcium between the floral bud and full flowering stages did not affect carbon dioxide (CO₂) assimilation, yield components and final yield. The results obtained in this research showed the lack of viability of foliar application of calcium and kinetin in order to increase pod set and number of seeds per plant in soybean crop.     

Analysis of soil microbial communities based on amplicon sequencing of marker genes

The use of cultivation independent methods has revolutionized soil biology in the last decades. Most popular approaches are based on directly extracted DNA from soil and subsequent analysis of PCR-amplified marker genes by next-generation sequencing. While these high-throughput methods offer novel possibilities over cultivation-based approaches, several key points need to be considered to minimize potential biases during library preparation and downstream bioinformatic analysis. This opinion paper highlights crucial steps that should be considered for accurate analysis and data interpretation.