Galerie de minéralogie et de géologie : description des collections, classement... des minéraux, roches, terrains et fossiles... précédés d'une notice historique... / par M. J.-A. Hugard,... ; Muséum d'histoire naturelle de Paris

Contient une table des matièresAvec mode text

Critical period of flower bud induction in peach trees associated with shoot length and bud position

International audienc

Weed suppression in cover crop mixtures under contrasted levels of resource availability

International audienceCover crop (CC) mixtures appear as a promising agroecological tool for weed management.Although CC supress weed growth by competing for resources, their suppressive effect undercontrasting levels of soil resource availability remains poorly documented. A two field: yearexperiment was conducted to investigate the weed suppressive effect of four CC mixtures.They were composed of 2 or 8 species including or not legume species and compared to abare soil control. The experiment included two levels of irrigation and nitrogen fertilisation atCC sowing. The objectives were to assess (i) weed and CC aboveground biomass response toCC mixtures and resource availability, (ii) the weed suppressive effect of CC mixtures across agradient of CC biomass and (iii) weed community response to CC mixtures and resourceavailability. CC and weed biomass were mainly influenced by interactions between CCmixtures and fertilisation and between CC mixtures and irrigation, with contrasted effectsbetween field: years. Nitrogen fertilisation increased biomass of non-legume based CCmixtures but this only resulted into a further reduction of weed biomass of little biologicalrelevance. Legume-based CC mixtures suppressed weeds to a greater extent without nitrogenfertilisation in year 2 but not in year 1, possibly due to contrasted initial soil nitrogenavailability (lower in year 2). Weed biomass generally benefited more from irrigation than CCmixtures. Among the 33 weed species recorded, weed communities in each plot weredominated by wheat volunteers, Geranium dissectum, Veronica persica and Echinochloa crusgalli, whose biomass varied depending on the interaction between year, CC mixture andresource availability. Our results revealed that competitive outcomes between CC mixturesand weed species were driven by a complex interaction between resource availability andspecies traits. Further experiments focusing on plant traits should improve our understandingof weed: CC competitive outcomes under various levels of resource availability

Carry over effects of cover crop mixtures and management practices on subsequent crops and weeds in no-till systems

Book of abstract p.372International audienceCover crop (CC) mixtures appear as a promising agroecological tool to suppress weeds andmaintain crop productivity while reducing chemical inputs such as herbicides and nitrogenfertilizers. The weed suppressive effect of CC and CC nitrogen release have been related to CCcomposition, soil resource availability and CC termination methods but the relative effect ofthese factors and their interactions remain poorly documented, especially in the case of CCmixtures. Most studies have focused on the subsequent spring crop, and hence, lacked toinvestigate long-term carry over effects of CC. A two field: year experiment was conducted toinvestigate the effect of CC mixture (2 or 8 species including or not legume species, comparedto a bare soil control), resource availability (water and nitrogen) at CC sowing and CCtermination method (rolling and glyphosate, compared to a winterkill control) on weedbiomass and productivity of two subsequent unweeded, unfertilized and direct seeded crops(spring barley and winter linseed in year 1 and 2, respectively). In the context of reduction ofherbicide use, our experiments showed that the use of CC to reduce weed biomass in thesubsequent crop was not relevant when CC were terminated by winter or rolling since CCprobably protected weeds from winter instead of creating a physical barrier for weedemergence, weed community composition in crop being mainly represented by weedvolunteers. Weed biomass was the main driver of the subsequent crop productivity but thelatter was enhanced after fertilised or legume-based CC, probably because of a highernitrogen release. No relevant long-term effect of CC on the subsequent crop was observed inour experiment, probably because nitrogen was used by the previous crop and weedcommunity composition changed by year. Our results highlight the importance CCcomposition and management for weed suppression and crop productivity in low-intensitybiodiversity-based cropping systems

A longitudinal rat model for assessing postoperative recovery and bone healing following tibial osteotomy and plate fixation

Abstract Background Rodent models are commonly employed to validate preclinical disease models through the evaluation of postoperative behavior and allodynia. Our study investigates the dynamic interplay between pain and functional recovery in the context of traumatic osteotomy and surgical repair. Specifically, we established a rat model of tibial osteotomy, followed by internal fixation using a 5-hole Y-plate with 4 screws, to explore the hypothesis that histological bone healing is closely associated with functional recovery. Objective Our primary objective was to assess the correlation between bone healing and functional outcomes in a rat model of tibial osteotomy and plate fixation. Methods Seventeen male Sprague–Dawley rats underwent a metaphyseal transverse osteotomy of the proximal tibia, simulating a fracture-like injury. The resultant bone defect was meticulously repaired by realigning and stabilizing the bone surfaces with the Y-plate. To comprehensively assess recovery and healing, we performed quantitative and qualitative evaluations at 2, 4, 6, and 8 weeks post-surgery. Evaluation methods included micro-CT imaging, X-ray analysis, and histological examination to monitor bone defect healing. Concurrently, we employed video recording and gait analysis to evaluate functional recovery, encompassing parameters such as temporal symmetry, hindlimb duty factor imbalance, phase dispersion, and toe spread. Results Our findings revealed complete healing of the bone defect at 8 weeks, as confirmed by micro-CT and histological assessments. Specifically, micro-CT data showed a decline in fracture volume over time, indicating progressive healing. Histological examination demonstrated the formation of new trabecular bone and the resolution of inflammation. Importantly, specific gait analysis parameters exhibited longitudinal changes consistent with bone healing. Hindlimb duty factor imbalance, hindlimb temporal symmetry, and phase dispersion correlated strongly with the healing process, emphasizing the direct link between bone healing and functional outcomes. Conclusions The establishment of this tibia osteotomy model underscores the association between bone healing and functional outcomes, emphasizing the feasibility of monitoring postoperative recovery using endpoint measurements. Our overarching objective is to employ this model for assessing the local efficacy of drug delivery devices in ameliorating post-surgical pain and enhancing functional recovery