International Journal of Agricultural Research, Innovation and Technology (IJARIT)
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Partitioning carbon sources between wetland and well-drained ecosystems to a tropical first-order stream – Implications for carbon cycling at the watershed scale (Nyong, Cameroon)
No full text(IF 5.09; Q1)International audienceTropical rivers emit large amounts of carbon dioxide (CO2) to the atmosphere, in particular due to large wetland-to-river carbon (C) inputs. Yet, tropical African rivers remain largely understudied, and little is known about the partitioning of C sources between wetland and well-drained ecosystems to rivers. In a first-order sub-catchment (0.6 km2) of the Nyong watershed (Cameroon 27 800 km2), we fortnightly measured C in all forms and ancillary parameters in groundwater in a well-drained forest (hereafter referred to as non-flooded forest groundwater) and in the stream. In the first-order catchment, the simple land use shared between wetland and well-drained forest, together with drainage data, allowed the partitioning of C sources between wetland and well-drained ecosystems to the stream. Also, we fortnightly measured dissolved and particulate C downstream of the first-order stream to the main stem of order 6, and we supplemented C measurements with measures of heterotrophic respiration in stream orders 1 and 5. In the first-order stream, dissolved organic and inorganic C and particulate organic C (POC) concentrations increased during rainy seasons when the hydrological connectivity with the riparian wetland increased, whereas the concentrations of the same parameters decreased during dry seasons when the wetland was shrinking. In larger streams (order > 1), the same seasonality was observed, showing that wetlands in headwaters were significant sources of organic and inorganic C for downstream rivers, even though higher POC concentration evidenced an additional source of POC in larger streams during rainy seasons that was most likely POC originating from floating macrophytes. During rainy seasons, the seasonal flush of organic matter from the wetland in the first-order catchment and from the macrophytes in higher-order rivers significantly affected downstream metabolism, as evidenced by higher respiration rates in stream order 5 (756 ± 333 gC-CO2 m−2 yr−1) compared to stream 1 (286 ± 228 gC-CO2 m−2 yr−1). In the first-order catchment, the sum of the C hydrologically exported from non-flooded forest groundwater (6.2 ± 3.0 MgC yr−1) and wetland (4.0 ± 1.5 MgC yr−1) to the stream represented 3 %–5 % of the local catchment net C sink. In the first-order catchment, non-flooded forest groundwater exported 1.6 times more C than wetland; however, when weighed by surface area, C inputs from non-flooded forest groundwater and wetland to the stream contributed to 27 % (13.0 ± 6.2 MgC yr−1) and 73 % (33.0 ± 12.4 MgC yr−1) of the total hydrological C inputs, respectively. At the Nyong watershed scale, the yearly integrated CO2 degassing from the entire river network was 652 ± 161 GgC-CO2 yr−1 (23.4 ± 5.8 MgC CO2 km−2 yr−1 when weighed by the Nyong watershed surface area), whereas average heterotrophic respiration in the river and CO2 degassing rates was 521 ± 403 and 5085 ± 2544 gC-CO2 m−2 yr−1, which implied that only ∼ 10 % of the CO2 degassing at the water–air interface was supported by heterotrophic respiration in the river. In addition, the total fluvial C export to the ocean of 191 ± 108 GgC yr−1 (10.3 ± 5.8 MgC km−2 yr−1 when weighed by the Nyong watershed surface area) plus the yearly integrated CO2 degassing from the entire river network represented ∼ 11 % of the net C sink estimated for the whole Nyong watershed. In tropical watersheds, we show that wetlands largely influence riverine C variations and budget. Thus, ignoring the river–wetland connectivity might lead to the misrepresentation of C dynamics in tropical watersheds
Les géographies du politique à l'épreuve de la géographie scolaire. Quelle place pour le politique dans les programmes scolaires ?
No full textNational audienceLa mise en place en 2020 d’une nouvelle spécialité « Histoire-Géographie, Géopolitique, Sciences politiques » en classe de Première et de Terminale est l’occasion d’affirmer l’importance des questions géopolitiques et témoigne de la volonté de faire acquérir une culture politique aux élèves dès le niveau secondaire. Elle s’inscrit plus largement dans un contexte de « retour du politique » et témoigne d’un regain d’intérêt pour les questions brûlantes qui agitent le monde contemporain : compréhension des rivalités entre puissances et sensibilisation aux grands défis géopolitiques, étude des formes de concurrence et de coopération dans un contexte de mondialisation, choix en matière de gestion et de préservation des ressources ou de lutte contre les risques et le changement global, débats et enjeux entre acteurs concernant l’aménagement et la gestion durable des territoires. Elargie à d’autres thématiques enseignées en collège-lycée (les questions d’environnement, de développement, d’inégalités, de justice spatiale…), elle pose la question de la place et du rôle du politique dans l’enseignement de la géographie.Étroitement associé à l’enseignement de l’histoire depuis la fin du XIXe siècle, l’enseignement de la géographie s’inscrit en France au service d’un projet politique, celui d’établir un socle républicain. Historiquement, il s’agit d’abord d’unir une nation à son territoire, de créer un sentiment d’appartenance dans le but de forger une communauté nationale. Sans abandonner leurs finalités civiques et patrimoniales, les programmes scolaires ont commencé à évoluer à partir de 1982 et surtout de 2008 vers une éducation géographique plus ouverte à "la compréhension du monde » et à « l’acquisition d’une citoyenneté active et critique, informée, distanciée et responsable » (Carroué, 2016). Ces finalités intellectuelles et critiques sont censées aller de pair avec une meilleure prise en compte des dimensions politiques. Dans les classes, la manière de composer avec le politique pour les enseignants est souvent ambivalente : elle peut aller d’un « refus du politique » (Audigier, 1993) à une prise en compte partielle, voire à une position assumée d’implication ou même d’engagement qui pose la question du devoir de neutralité de l’enseignant.Dans ce chapitre, il s’agit dans un premier temps de comprendre pourquoi la géographie scolaire a longtemps évacué la question du politique et comment celle-ci a pu commencer progressivement à être prise en charge. Dans un second temps sont abordés les enjeux importants concernant le traitement des questions politiques dans l’enseignement de la géographie
Interaction entre échocardiographie et système rénine-aldostérone comme prédicteurs de mortalité pour le COVID-19
No full textInternational audienc
Titanium nanoparticles fate in small-sized watersheds under different land-uses
No full textInternational audienceSurface waters from three catchments having contrasting land-uses (forested, agricultural, and urban) were sampled monthly and analysed for nanoparticulate titanium dioxide (NPs-TiO2) by single particle ICPMS and electron microscopy. We report one-year of data for NPs-TiO2 having average number and mass concentrations of 9.1 x 108 NPs-TiO2 particles L-1 and 11 μg NPs-TiO2 L-1 respectively. An increase in concentration during warmer months is observed in the forested and agricultural catchments. Both concentrations of NPs-TiO2 are within the range of recently reported values using similar analytical approaches. The positive correlations for NPs-TiO2 mass concentration or particle number with the concentration of some trace elements and DOC in the forested and agricultural catchments suggest the detected NPs-TiO2 in these two systems are mostly from geogenic origin. Additionally, microscopy imaging confirmed the presence of NPs in the three catchments. Furthermore, the land-area normalized annual flux of NPs-TiO2 (1.65 kg TiO2 year-1 km-2) was highest for the agricultural catchment, suggesting that agricultural practices have a different impact on the NPs-TiO2 dynamics and exports than other land-uses (urban or forestry). A similar trend is also found by the reanalysis of recent literature data
Whitlockite structures in kidney stones indicate infectious origin: a scanning electron microscopy and Synchrotron Radiation investigation
No full textInternational audienceDans cette contribution, nous étudions les calculs rénaux contenant la whitlockite (Wk). En premier lieu, la présence du fer dans la formule stœchiométrique de la Wk est discutée grâce à la fluorescence X. Puis, nous abordons la relation à l’infection à l’aide d’observations au Microscope électronique à balayage (MEB) aptes à mettre en évidence de possibles empreintes de bactéries. Elles montrent que le processus infectieux est établi pour des teneurs supérieures à 20%, ceux-ci ne pouvant toutefois pas être écartés en dessous de cette teneur. Finalement, l’étude de relation entre la taille des cristaux de Wk et l’infection par DRX ne permet pas de l’établir. Le message pour le clinicien est le suivant : pour un patient asymptomatique, si le calcul ne contient ni struvite, ni apatite carbonatée et moins de 20% de Wk, il convient d’observer par MEB les calculs rénaux afin de pouvoir écarter ou non un processus infectieux
Evaluation of improved hermaphrodite papaya (Carica papaya L.) varieties at Arba Minch, Southern Ethiopia
Get PDFThe experiment was conducted to evaluate the adaptability of newly released papaya varieties at Chano Mille research site of Arba Minch Agricultural Research Center during 2019-2020 cropping seasons. The three hermaphrodite papaya varieties namely; Braz-HS1, Koka-HM1 and Meki-HL1 were used for the study and laid-out in a Randomized Complete Block Design in three replications. Data on yield and yield components were collected and analyzed by using analysis of variance (ANOVA) through Statistical Analytics System software. The ANOVA results revealed that there were significant variations among papaya varieties for the studied parameters. Significantly, the highest number of fruits plant-1, number of leaves and fruit yield were obtained from Braz-HS1 papaya variety. The fruit yield of Braz-HS1 variety was 46% higher than that of Koka-HM1. In general, Braz-HS1 papaya variety performed (in terms of number of fruits and fruit yield) better than the rest two varieties. Thus, Braz-HS1 papaya variety could be recommended for the papaya growers in the study area and vicinity with similar agro-ecology.
Int. J. Agril. Res. Innov. Tech. 11(2): 69-71, Dec 202
Molecular characterization and in vitro control measures of fruit rot disease of Sweet pepper
Get PDFFruit rot disease of sweet pepper is one of the main fungal diseases causing huge economic losses to the grower. An experiment was conducted to find out the fungal pathogen associated with fruit rot disease of sweet pepper, obtained from experimental fields of Jahangirnagar University, Bangladesh. Fruit rot disease-causing fungus was isolated from infected fruits and identified using morphological characterization based on colony features, mycelia, conidia as well as molecular characterization based on internal transcribe spacer (ITS) region of the fungus. ITS sequence of our studied fungus MH368146.1 was genetically 99-100% similar to sequences of Fusarium solani in NCBI database. Typical fruit rot symptoms were reproduced by artificial inoculations of the isolated fungus. The mycelial growth of this fungus was evaluated on ten different solid culture media i.e., Potato Dextrose Agar, Yeast Extract Agar, Honey Peptone Agar, Hansen’s Medium, Sabouraud’s Glucose Agar, Kauffman’s Agar, Potato Sucrose Agar, Richard’s Agar and Carrot Agar. Fungus grew well on all tested solid culture media. Several bio-control agents and two commercial fungicides were evaluated against isolated fungus under in vitro condition, in which the highest percent inhibition of radial growth of the fungus was determined as 64.75% due to Trichoderma reesei isolate 2, and 60.63% by Tilt 250 EC (500 ppm) at 7 days post-incubation. Therefore, T. reesei was found as the most suitable to control the growth of F. solani under laboratory conditions. However, further pot and field trials needed to be confirmed the bio-control potential of it.
Int. J. Agril. Res. Innov. Tech. 11(2): 108-116, Dec 202
An overview of genotype x environment interaction and yield stability analysis in applied plant breeding: great emphasis given to coffee (Coffea arabica L.)
Get PDFThe inconsistence of genotypes across location during plant breeding is the major challenges to the breeder. That is the differential response of genotypes to different environment. Meanwhile stability is the ability of a genotype to withstand stressful conditions and yet be able to produce yield. Thus, stability is an absolute and relative measure. Arabica coffee has location specific adaptation nature and that leads to highly significant instability in its breeding program. In the study of coffee bean yield stability cultivars tested at multi- locations within the domain of coffee growing ecologies of Ethiopia, showed a significant genotype x environment interaction. The review of previous research also indicated inconsistent effects of genotype x environment interaction on cup quality. Yield-stability analysis is very important in measuring cultivar stability and suitability for growing crops across seasons and agro-ecological region to identify stable genotype. The yield stability have been challenge to the plant breeders and biometricians, it complicates the selection of superior genotypes. It is important to minimize the usefulness of the genotype across environments for selecting. Since approach of plant breeding is to develop genotypes that are, optimum for the condition under which they will be grown breeders have to manage yield instability throughout formalized procedures of plant breeding. During stability measurement if the variance is found to be significant, various methods of measuring the stability of genotypes can be used to identify the stable genotype(s). Most of stability analysis parameters are briefly discussed in this review.
Int. J. Agril. Res. Innov. Tech. 11(2): 117-123, Dec 202
Performance evaluation of Mung bean [Vigna radiata (L.) Wilczek] varieties in pastoral areas of South Omo Zone, Southern Ethiopia
Get PDFField experiments were conducted on pastoral and agro-pastoral areas of South Omo Zone at Dasenech, Hammer and Gynagatom woredas of Southern Ethiopia on mung bean [Vigna radiata (L.) Wilczek] varieties in 2019 under irrigated condition. The objective of the study was to select the best performing mung bean varieties in the target areas. The treatments involved in the study were three improved and one local mung bean variety (NVL-01, Shewarobit, N-26, and local). The experiment was carried out using a randomized complete block design (RCBD) with three replications. The combined analysis of variance result for mean squares depicted that there were significant differences observed among the varieties for all the studied parameters except the number of seeds per pod. The overall mean values for plant height ranged from 41.33 cm for Shewarobit to 62.00 cm for the local check. The mean values for the number of pods per plant ranged from 19.33 for the local check to 24.44 for NVL-01. The mean value for a thousand seeds weight was maximum 59.56 g for N-26, while it was a minimum 48.22 g for Shewarobit. The highest overall mean grain yield of 2483.8 kg ha-1 was recorded for N-26 while the minimum 1462.6 kg ha-1 was noted for the local check. The grain yield advantages of 41.11, 34.52, and 25.26% were obtained from the improved varieties N-26, NVL-01, and Shewarobit, respectively over the local check. The effect of varieties on grain yield was significant and the best performing mung bean varieties namely N-26 2483.8 kg ha-1 and NVL-01 2233.6 kg ha-1 would be recommended for the specific community and its vicinity even though further study should be carried out including some recently released varieties for improved mung bean production and also to put the recommendation on a strong basis.
Int. J. Agril. Res. Innov. Tech. 12(1): 141-144, June 202
Teff growth and yield response to blended fertilizer type and rate in Debub Ari and Bena Tsemay Districts, Southwestern Ethiopia
Get PDFDepleting of soil fertility, soil organic matter, macro-and micro-nutrients and crop nutrient imbalances are among the primary biophysical limitations that reduce the production of teff. The experiment was conducted to evaluate teff response to blended fertilizer types and rates in Debub Ari and Bena Tsemay districts. Control, Recommended NP, 3 dosages of NPS and NPSB blended fertilizer rates each were used that is laid out in RCBD following three replication. The full dose of blended and P fertilizers was applied at planting and urea was applied in two splits. The result was revealed that application of 200 kg ha-1 NPSB + 127 kg ha-1 Urea resulted in the highest grain yield of 2299.5 kg ha-1 in Debub Ari and 200 kg ha-1 NPS + 117 kg ha-1 Urea gives 1809.2 kg ha-1 in Bena Tsemay, while the lowest grain yield was recorded from the nil in both districts. However, the highest economic return was obtained in response to the application of 64 kg ha-1 N + 20 kg ha-1 P in both districts. Application of 64 kg ha-1 N + 20 kg ha-1 P gives 57.24% and 14.42% yield increment in Debub Ari and Bena Tsemay, respectively; also 54.47% and 7.57% increment in economic return in Debub Ari and Bena Tsemay in the same order over the control. Application of 64 kg ha-1 N + 20 kg ha-1 P was recommended for the production of teff on the study area and similar agro-ecologies, as it was optimum for improving teff production. Further investigation should be done on plant nutrient uptake and using efficiency and grain quality.
Int. J. Agril. Res. Innov. Tech. 12(1): 145-154, June 202