Optimizing N fertilizer use for sesame under rain fed and irrigation conditions in Northern Ethiopia

Inappropriate use of fertilizers is one of the major production constraints in sesame. Studies on N fertilizer optimization on sesame were conducted at Humera Agricultural Research Center(Hu ARC) under rain fed and irrigation conditions. Thirteen(13) N doses were evaluated in a Randomized Complete Block Design(RCBD)during 2016–2018 for rainfed conditions and 2017 to 2019 for irrigation conditions. The study was conducted with objective to optimize N fertilizer use for sesame. In the rainfed condition, the results demonstrated a prolonged duration to reach 50% flowering with higher nitrogen(N) application rates. The application of 52.5–110kg N ha^(-1) resulted in significantly higher seed yield, while lower(18 kg N ha^(-1)) and higher(156 kg N ha^(-1)) doses of N led to reduced seed yield. Under irrigation conditions, superior seed weights and maximum seed yield were observed at 64 and 75 kg N ha^(-1), whereas lower N doses resulted in diminished seed yield. The agronomic efficiency of N fertilizer(N-AE) was found to be highest at the rate of 64 kg N ha^(-1) under both growing conditions.The partial budget analysis revealed that applying 64 kg N ha^(-1) for rainfed cultivation and between 64 and 75 kg N ha^(-1) for irrigated sesame production yielded greater net profit, MRR, and residual ranking. Therefore, it is recommended to apply a rate of 64 kg N ha^(-1) for rainfed sesame cultivation and between 64 up to 75 kg N ha^(-1) for the irrigated sesame inorder to increase the productivity of this crop.

Carbon stock potential of scattered trees on farmland along an altitudinal gradient in Tigray,Northern Ethiopia

Introduction:Trees on agricultural landscape play a vital role in ecosystem services including food security that supports human livelihood.They can further offer synergy between adaptation and mitigation in addressing climate change impact.Understanding aboveground tree biomass and soil organic carbon stocks along the altitudinal gradient provide opportunities for better management of the carbon pools.However,little is known on how altitudinal gradient influences on carbon stock of woody biomass and soil of scattered trees on farmland,particularly in a dry area.Methods:The study area were stratified in to five class(500–1000,1000–1500,1500–2000,2000–2500,and 2500–3000 m a.s.l).Quadrats(100 m×50 m)were randomly selected from each of stratified altitudinal gradients.At every sampling point,one composite soil sample was taken at 60 cm soil depth for soil organic carbon analysis.For the purpose of woody biomass estimation,allometric equations developed for a similar area were used.Finally,aboveground biomass carbon(AGC),belowground biomass carbon(BGC),soil organic carbon(SOC),and total carbon stock(TC)status were estimated and variables were compared using one-way analysis of variance(ANOVA).Results:The result indicated that AGC,BGC,SOC,and TC varied significantly(p<0.05)along with an altitudinal gradient.The upper altitude(2500–3000 m a.s.l)AGC,BGC,SOC,and TC stock was estimated as 17.97 Mg C ha^(−1),6.53 Mg C ha^(−1),23.09 Mg C ha^(−1),47.59 Mg C ha^(−1) respectively,and significantly higher than the other altitudinal gradient.Conclusions:We conclude that scattered trees on farmland hold a high potential of carbon storage which may greatly contribute to the climate resilience green economy strategy and their conservation should be promoted.

Pichia pastoris composition expressed aerolysin mutant of Aeromonas veronii as an oral vaccine evaluated in zebrafish(Danio rerio)

Vaccines are one of the most practical means to stop the spreading of Aeromonas veronii in aquaculture.In this study,virulence factor aerolysin mutant NTaer which has lost its hemolytic activity was used as a target antigen.Pichia pastoris constitutive secretory expression NTaer(GS115-NTaer)was used as a potential safe oral vaccine to evaluate its effectiveness on zebrafish immunity.The result shows that vaccination of GS115-NTaer for four weeks did not affect the growth performance of the host,while eliciting an effective immune protective response.Compared with the control group,the GS115-NTaer could significantly up-regulate the relative expression level of the intestinal tight junction protein 1α(TJP1α)gene,and significantly increased the contents of lysozyme(LYZ),complement C3 and C4 in the gut,indicating that the innate immune response of the fish was activated.The relative gene expression levels of macrophage-expressed gene 1(MPEG1)and T cell receptor(TCR-α)in the gut,and MPEG1,CD4,CD8,TCR-α,GATA3,and T-bet in the spleen were all increased significantly,indicating that the cellular immune response of the fish was activated.Furthermore,the contents of serum IgM and intestinal mucosa IgZ antibodies were significantly increased,which showed that humoral immunity was also activated.Moreover,inoculation with GS115-NTaer significantly changed the structure of gut microbiota.In particular,the relative ratio of(Firmicutes+Fusobacteriota+Bacteroidota)/Proteobacteria was significantly higher than that of the control and GS115 groups.Lastly,the vaccinated fish were challenged with A.veronii,and the relative percent survival of GS115 and the GS115-NTear groups was 14.28%and 33.43%.This improvement of immunity was not only due to the specific immune response but also attributed to the improvement of innate immunity and the gut microbiota which was demonstrated by the germ-free zebrafish model.Collectively,this study provides information on the effectiveness of GS115-NTear as an oral vaccine for the green prevention and control of A.veronii infection in fish aquaculture.

Current and future predicting potential areas of Oxytenanthera abyssinica(A.Richard)using MaxEnt model under climate change in Northern Ethiopia

Introduction:Climate change will either improve,reduce,or shift its appropriate climatic habitat of a particular species,which could result in shifts from its geographical range.Predicting the potential distribution through MaxEnt modeling has been developed as an appropriate tool for assessing habitat distribution and resource conservation to protect bamboo species.Methods:Our objective is to model the current and future distribution of Oxytenanthera abyssinica(A.Richard)based on three representative concentration pathways(RCP)(RCP2.6,RCP4.5,and RCP8.5)for 2050s and 2070s using a maximum entropy model(MaxEnt)in Northern Ethiopia.For modeling procedure,77 occurrence records and 11 variables were retained to simulate the current and future distributions of Oxytenanthera abyssinica in Northern Ethiopia.To evaluate the performance of the model,the area under the receiver operating characteristic(ROC)curve(AUC)was used.Results:All of the AUCs(area under curves)were greater than 0.900,thereby placing these models in the“excellent”category.The jackknife test also showed that precipitation of the coldest quarter(Bio19)and precipitation of the warmest quarter(Bio18)contributed 66.8%and 54.7%to the model.From the area of current distribution,1367.51 km2(2.52%),7226.28 km2(13.29%),and 5377.26 km2(9.89%)of the study area were recognized as high,good,and moderate potential habitats of Oxytenanthera abyssinica in Northern Ethiopia,and the high potential area was mainly concentrated in Tanqua Abergele(0.70%),Kola Temben(0.65%),Tselemti(0.60%),and Tsegede(0.31%).Kafta Humera was also the largest good potential area,which accounts for 2.75%.Compared to the current distribution,the total area of the high potential regions and good potential regions for Oxytenanthera abyssinica under the three RCPs(RCP2.6,RCP4.5,and RCP8.5)would increase in the 2050s and 2070s.However,the total area of the least potential regions under the three RCPs(RCP2.6,RCP4.5,and RCP8.5)in 2050s and 2070s would decrease.Conclusion:This study can provide vital information for the protection,management,and sustainable use of Oxytenanthera abyssinica,the resource to address the global climate challenges.

Dispersed trees on smallholder farms enhance soil fertility in semi-arid Ethiopia

Introduction:Dispersed trees such as Oxytenanthera abyssinica(A.Rich.)and Dalbergia melanoxylon(Guill.&Perr.)which are objectively maintained or planted on farmland provide a significant contribution to soil fertility improvement.However,there was no quantitative information on the level of soil nutrient additions of these trees to the soil system.Methods:This study was conducted on the farmers’fields in Kafta Humera district,Tigray region(northern Ethiopia),where mature stands of O.abyssinica and D.melanoxylon trees exist.Radial distance-based soil sampling(under the canopy,near to canopy,and far from canopy)was adopted to quantify the role of these trees on soil fertility improvement.Soil parameters tested were soil reaction(pH),total nitrogen(TN),available phosphorus(AvP),electrical conductivity(EC),cation exchange capacity(CEC),and organic carbon(OC).Results:There was a negative linear relationship between the radial distance of the O.abyssinica tree trunk and soil TN,OC,CEC,and AvP contents but not for pH.Similarly,negative linear relationship between distance from D.melanoxylon and TN,OC,and AvP was obtained.The average total nitrogen(0.26%and 0.13%),available phosphorus(7.21 ppm and 6.37 ppm),and organic carbon(1.73%and 1.02%)contents were respectively higher under the tree canopies of O.abyssinica and D.melanoxylon compared with the adjacent open canopies.The amount of soil OC,TN,AvP,and CEC under O.abyssinica tree species was also significantly higher by 69%,100%,13%,and 42%compared to that of D.melanoxylon tree species.However,the amount of EC and soil pH was significantly lower by 57%and 19%,respectively.Conclusion:In general,O.abyssinica and D.melanoxylon added a significant amount of nutrients to the soil.Thus,retaining these important tree species on farmland played a positive role in replenishing soil fertility for resource-constrained households so as to reduce chemical fertilizer amendments.