Effect of fertilization of a biochar and compost amended technosol: Consequence on Ailanthus altissima growth and As- and Pb-specific root sorption

The remediation of metal(loid) polluted soil using plants (i.e. phytoremediation) often requires the application of amendments, as well as chemical fertilizer. However, such fertilizers can have negative effects when applied alone and can thus be applied together with other organic amendments to diminish this negative effect. Finally, plants to be used in phytoremediation should be selected based on their adaptive capacity and tolerance to poor and highly contaminated soils, characteristics that possesses Ailanthus altissima. The objective of this study was to evaluate the effects of osmocote fertilization on the amended mining technosol properties and plant growth parameters, as well as to study the accumulation pattern of As and Pb in plant roots. Results showed that osmocote ameliorated soil conditions, but increased Pb mobility. It also greatly improved plant growth. Finally, different behaviours of metal(loid) accumulation were observed in the roots: As was absorbed mainly in the roots because of its similarity with P, with very low amounts in the leaves, whereas Pb was adsorbed mainly on the root surface, with lesser proportion absorbed inside the root system.     

Issues and challenges in landscape models for agriculture: from the representation of agroecosystems to the design of management strategies

Context

Agroecosystems produce food and many other services that are crucial for human well-being. Given the scales at which the processes underlying these services take place, agricultural landscapes appear as appropriate spatial units for their evaluation and management. The design of sustainable agricultural landscapes that value these services has thus become a pressing issue but faces major challenges stemming from the diversity of processes, their interactions and the number of scales at stake. Agricultural landscape modelling can provide a key contribution to this design but must still overcome several difficulties to offer reliable tools for decision makers.

Objectives

Our study aimed at shedding light on the main scientific and technical difficulties that make the building of landscape models that may efficiently inform decision-makers a complex task, as well as translating them in terms of challenges that can be further investigated and discussed.

Methods

We examine current issues and challenges and indicate future research needs to overcome the scientific and technical obstacles in the development of useful agricultural landscape models.

Results

We highlight research perspectives to better couple landscape patterns and process models and account for feedbacks, integrate the decisions of multiple stakeholders, consider the spatial and temporal heterogeneity of data and processes, explore alternative landscape organisations and assess multiobjective performance.

Conclusion

Coping with the issues and challenges discussed in this paper should improve our understanding of agroecosystems and give rise to new hypotheses, thereby informing future research.

     

Early ovine preantral follicles have a potential to grow until antral stage in two‐step culture system in the presence of aqueous extract of Justicia insularis

The objective of this study was to determine whether preantral follicles cultured in vitro for 7 days within ovine ovarian cortical strips could be isolated at the secondary follicles (SF) and grown until antral stage during an additional 6 days period of in vitro culture in the presence of aqueous extract of Justicia insularis. Fresh ovarian fragments from 16 adult sheep were fixed for histological analysis (Control 1) or in vitro cultured individually in α‐MEM⁺ supplemented with 0.3 mg/ml J. insularis (Step 1) for 7 days. Part of the fragments then were fixed for histological analysis (in vitro culture group). Remaining fragments were exposed stepwise to increasing trehalose concentrations before immediate isolation of SF and viability assessment (Control 2) or after 6 days of culture in α‐MEM⁺⁺ supplemented with 0.3 mg/ml J. insularis (Step 2). In Step 1, percentage of follicular activation was 80%. In Step 2, a significant increase (p < 0.05) in follicular diameter and antrum formation within 6 days in vitro culture of isolated follicles was achieved. The total antioxidant capacity from both steps significantly increase (p < 0.05) from day 2 to day 6. Confocal analysis of oocytes showed 57.14% oocytes with homogeneous distribution and 42.86% with peri‐cortical distribution. In conclusion, SF can be successfully isolated from sheep ovarian cortex after 7 days of culture and are capable of surviving and forming an antral cavity if cultured in vitro for an additional 6 days in the presence of 0.3 mg/ml J. insularis.     

COMPARATIVE STUDY OF SCROTAL AND PRESCROTAL CASTRATION IN PET RABBITS (ORYCTOLAGUS CUNICULUS)

Castration of rabbits can be achieved with several surgical techniques. The choice of the technique currently depends on surgeon preference since objective comparison between techniques is lacking. The aim of the current study was to compare the scrotal and prescrotal approaches in pet rabbits. The surgery and anesthesia duration, the postoperative appetite and feces production, and the postoperative complications were compared. Thirteen rabbits were randomly assigned to the scrotal or prescrotal castration groups. Appetite, fecal output, surgical incisions, and scrotums were evaluated at 8 hourse, 24 hours, 32 hours, and 7 days after surgery. Scrotal edema at 8, 24, and 32 hours and anesthesia duration were significantly higher in the scrotal group compared to the prescrotal group (P = 0.008, P = 0.013, P = 0.021, and P = 0.034, respectively). A nonsignificant tendency toward a higher rate of licking and mutilation behaviors was observed in the scrotal group 24 hours postsurgery. No other complications were observed in either group. All rabbits quickly recovered a normal appetite and fecal output, and all surgical incisions healed without issue. Although the prescrotal technique was associated with less complications, both techniques were considered safe options for rabbits in this study.     

Growth, allocation and leaf gas exchanges of hybrid poplar plants in their establishment phase on previously forested sites: effect of different vegetation management techniques

The effect of different vegetation control methods (mowing and cultivation between plantation rows, herbicide application and cover plant sowing) on hybrid poplar (P. maximowiczii × balsamifera) growth, biomass allocation and leaf carbon assimilation was investigated in two plantations (1- and 2-year-old) established in previously forested sites of south-eastern Québec. Any vegetation control treatment applied the same year in which the plantation was established did not have an effect on hybrid poplar aboveground growth. However significant differences among treatments were observed belowground, where the removal of the competing vegetation at the tree base increased the fine root:leaf biomass ratio of plants, thus probably facilitating their establishment. In contrast, 2-year-old plants grew better when treated with herbicides, but no positive effect of the mechanical treatments was detected. In both sites, trees growing on herbicide-treated plots showed considerably higher leaf carbon assimilation and leaf N concentration which were both strongly correlated. We conclude that a strong vegetation competition for nutrients takes effect on hybrid poplar plantations on previously forested sites since there was no water shortage for any treatment during the study period.     

Radial profiles of sap flow with increasing tree size in maritime pine

We investigated the radial variation of sap flow within sapwood below the live crown in relation to tree size in 10-, 32-, 54- and 91-year-old maritime pine stands (Pinus pinaster Ait.). Radial variations were determined with two thermal dissipation sensors; one measured sap flux in the outer 20 mm of the xylem (Jref), whereas the other was moved radially across the sapwood in 20-mm increments to measure sap flux at multiple depths (Jref). For all tree sizes, sap flow ratios (Ri = JiJref (-1)) declined with increasing sapwood depth, but the decrease was steeper in trees with large diameters. Correction factors (C) were calculated to extrapolate Jref for an estimate of whole-tree sap flux. A negative linear relationship was established between stem diameter and C, the latter ranging from 0.6 to 1.0. We found that neglecting these radial corrections in 10-, 32-, 54- and 91-year-old trees would lead to overestimation of stand transpiration by 4, 14, 26 and 47%, respectively. Therefore, it is necessary to account for the differential radial profiles of sap flow in relation to tree size when comparing tree transpiration and hydraulic properties among trees differing in size.     

Elite durum wheat genetic map and recombination rate variation in a multiparental connected design

Genetic maps published for elite durum wheat (Triticum turgidum durum Desf.), were mainly related to Italian and North American pools. To provide additional information dedicated to durum elite pool, a recombinant inbred population (217 RILs) derived form 2 French commercial varieties (Ixos and Primadur), has been mapped with 529 loci (98 AFLPs, 67 SSRs, 1 ISBP and 363 DArTs). Genetic map spanned a total of 2,082 cM (5.7 cM/marker on average). Recombination rate variation over the genome was documented through the analysis of six segregating populations representing a total of 48 RILs × 6, issued from an half diallel design based on four elite lines—Neodur, Ixos, Lloyd and Primadur—including the 2 previous genitors. Each set of three genetically connected populations (48 RILs × 3) was used to build the consensus parental maps for each genitor. To construct the four consensus parental maps, marker ordering was determined on 217 RILs map which was an extended population of the most polymorphic cross (Ixos × Primadur). Sizeable, recombination rate variation has been observed between the four parental maps both at the marker pair scale and at the linkage group scale. Two of the parents, Lloyd and Primadur, had strong, opposite effects increasing and decreasing, respectively the recombination rate. Additional studies are proposed to increase our understanding of this variation, with the identification of environmental or genetic factors affecting recombination rate.