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.

Large scale genetic landscape and population structure of Ethiopian sesame (Sesamum indicum L.) germplasm revealed through molecular marker analysis

Sesame(Sesamum indicum L.) plays a crucial role in Ethiopian agriculture,serving both subsistence and commercial purposes.However,our understanding of the extensive genetic diversity and population structure of Ethiopian sesame remains limited.To address this knowledge gap,we genotyped 368 Ethiopian sesame germplasms,categorizing into four distinct breeding groups:Accessions,landraces,improved varieties,and wild types,using a comprehensive set of 28 polymorphic markers,including 23 simple sequence repeat(SSR) and five Insertion-Deletion(InDel) markers.These markers ensured robust genomic representation,with at least two markers per linkage group.Our results unveiled substantial genetic diversity,identifying a total of 535 alleles across all accessions.On average,each locus displayed 8.83 alleles,with observed and expected heterozygosity values of 0.30 and 0.36,respectively.Gene Diversity and Polymorphic Information Content(PIC) were recorded at 0.37 and 0.35.The percentage of polymorphic loci varied significantly among breeding groups,ranging from8.00% to 82.40%,indicating high diversity in accessions(82.4%),moderate diversity in improved varieties(31.20%) and landraces(29.60%),and limited diversity in wild types(8.00).Analysis of Molecular Variance(AMOVA) results emphasized significant genetic differentiation among populations,with substantial diversity(P<0.001) within each population.Approximately 8% of the entire genetic diversity could be attributed to distinctions among populations,while the larger proportion of genetic diversity(92%) resided within each individual sesame population,showcasing heightened diversity within each group.Our study’s findings received support from both Bayesian clustering and Neighbor-joining(NJ) analysis,reaffirming the credibility of our genetic structure insights.Notably,Population structure analysis at its highest Δk value(k=2) revealed the existence of two primary genetic clusters,further subdivided into four sub-populations at k=4.Similarly,NJ analysis identified two prominent clusters,each displaying additional sub-clustering.In conclusion,our research provides a comprehensive understanding of genetic groups,subpopulations,and overall diversity within Ethiopian sesame populations.These findings underscore the significant genetic diversity and population structure within Ethiopian sesame germplasm collections.This genetic richness holds promise for breeding and conservation efforts,highlighting the importance of preserving genetic diversity to ensure adaptation to changing environments and meet the needs of farmers and consumers.

Screening and evaluation for antibiosis resistance of the spring wheat accessions to the grain aphid,Sitobion miscanthi(Takahashi)(Hemiptera:Aphididae)

Resistant cultivar deployment is an effective method for cereal aphid management.Under greenhouse conditions,preliminary antibiosis resistance screening was conducted on 114 Ethiopian and 22 Chinese spring wheat accessions.After performing a bioassay to determine antibiosis resistance,aphid feeding behaviour and phenolic acid content analyses were performed on the aphid resistant wheat accessions by electrical penetration graph(EPG)and high performance liquid chromatography(HPLC),respectively.Among the wheat accessions,two high resistances,27moderate-resistances,and 35 low-resistances to Sitobion miscanthi were identified.The antibiosis resistance test showed prolonged pre-adult and pre-reproductive periods,shorter reproductive periods,lower fecundity,an intrinsic rate(rm)of increase,and a finite rate(λ)of increase of S.miscanthi on Lunxuan 145,Wane,Lunxuan 6,204511,Lunxuan 103and 5215 than those on the aphid-susceptible accession Beijing 837.The changes for the parameters of aphid feeding behaviour,including spending a longer time in the penetration and phloem salivation phases and less time in the phloem sap-feeding phase on the resistant wheat accessions,indicated that the aphid resistance may occur during the phloem phase and may be due to difficulties in the mechanical probing of the mesophyll cells.Additionally,the HPLC analysis showed higher contents of:1)ferulic acid in Lunxuan 145,Lunxuan 103 and Lunxuan 6;2)p-coumaric acid in Lunxuan145;3)vanillic acid in Lunxuan 145,Wane and Lunxuan 6;4)syringic acid in Lunxuan 103;and 5)caffeic acid in 5215.The contents of some phenolic acids within wheat leaves,such as p-courmaric acid and vanillic acid showed significant positive correlation with the duration of aphid development,but negative correlation with the aphid fecundity.The concentrations of these acids may be the causes of antibiosis resistance to S.miscanthi.The identification of grain aphid-resistant wheat accessions in our study will be helpful in future breeding program for pest control.

Long noncoding RNAs:new insights in modulating mammalian spermatogenesis

Spermatogenesis is a complex differentiating developmental process in which undifferentiated spermatogonial germ cells differentiate into spermatocytes,spermatids,and finally,to mature spermatozoa.This multistage developmental process of spermatogenesis involves the expression of many male germ cell-specific long noncoding RNAs(lncRNAs)and highly regulated and specific gene expression.LncRNAs are a recently discovered large class of noncoding cellular transcripts that are still relatively unexplored.Only a few of them have postmeiotic;however,lncRNAs are involved in many cellular biological processes.The expression of lncRNAs is biologically relevant in the highly dynamic and complex program of spermatogenesis and has become a research focus in recent genome studies.This review considers the important roles and novel regulatory functions whereby lncRNAs modulate mammalian spermatogenesis.

Temporal and Spatial Factors Affecting the Nature of Genotype x Environment Interaction in Sugarcane (<i>Saccharum officinarum L.</i>) under Ethiopian Agro-Climatic Conditions: An Integrated Approach

Analytical approaches are important for identification the causes of Genotype x environment interaction (GEI) in multi-environment trials (MET). The objectives of this investigation were to explore the nature and causes of the GEI in sugarcane under Ethiopian agro ecological conditions. Data of Cane yield, recoverable sucrose% and sugar yield obtained from 13 test environments were subjected to Additive Main and Multiplicative Interaction (AMMI2) for empirical study. For environmental characterization, mean values of twenty seven temporal and spatial factors were subjected to Principal Component Analysis (PCA). Moreover, to identify the environmental factors affecting the patterns of GEI and its components, mean values of these factors were correlated with environment AMMI2 IPCA scores of the yield traits studied. Results of the present study indicated that the GEI accounted for larger variation than the genotypic effects which suggested its importance and complexity. The PCA bi-plot successfully identified the environmental factors that most discriminated the test environments (crop years and locations). The correlation analysis between the environmental factors and environmental AMMI2 IPCA scores adequately identified the environmental factors affecting GEI and its components. Soil organic matter% and soil clay%, pan evaporation at establishment, relative humidity at growth stage and harvesting month were the major factors that substantially affect the GEI interaction patterns in cane yield while maximum relative humidity recorded during the growing season, all temperature regimes recorded during the entire growing season and at different crop stages were the major factors that affect GEI in recoverable sucrose%. Moreover, the pattern of GEI in sugar yield was significantly affected by harvest age, percent of clay in soil, altitude, relative humidity at harvest and pan evaporation at establishment. For efficient environmental selection and networks, genotype evaluations and formulation of appropriate sugarcane breeding strategy, f METs should adopt the inclusion of these environmental factors identified as major factors influencing the patterns of GEI. Moreover, more information will be generated if other physiological and soil moisture stress indices are included in future GEI studies in sugarcane.

In Vitro Screening of Cactus [Opuntia ficus-indicia (L.) Mill] Genotypes for Drought Tolerance

Drought is one of the complex environmental factors affecting growth and yield of crops in arid and semi-arid areas of the world. In this context, this investigation was carried out to select drought tolerance cactus genotypes under in vitro condition. An experiment was carried out at Laboratory of Mekelle Agricultural Research Center, Northern Ethiopia. Six cactus pear genotypes namely, Gerao, Keyih Beles, Shenkor, Limo, Lemats Beles and Suluhna were used. Areoles were used as explants in tissue culture. The non-ionic water soluble polymer polyethylene glycol (PEG) of molecular weight 6000 was used as osmoticum to simulate water stress. In the first culture, the MS medium was supplemented with (2, 4-D (4 mg/l) and BA (0.5 mg/l) for callus induction. In all cultures MS medium was supplemented with 0, 10, 20 and 40 g/l polyethylene glycol (PEG) and was solidified with 0.8% agar and 30 g of sucrose. Significant differences were observed among the genotypes, PEG levels. In the first culture highest number of explants initiated callus on medium supplemented with no PEG but had not shown significant difference with 10 g/l PEG. At 10 g/l PEG, the callus induction frequency, callus fresh weight and plantlet regeneration were recorded highest for Suluhna (83.3%, 5.5 g and 63.3%), respectively. At 40 g/l PEG, callus induction frequency, callus fresh weight and plantlet regeneration were produced highest for Suluhna (41.7%, 2.75 g and 45%), respectively but no significant difference with Gerao, Limo and Lemats Beles. However, Shenkor and Keyih Beles were induced callus but became reddish black within 35 days supplemented with 40 g/l PEG. Both shoot and root production decreased with increased PEG level in the medium. At 40 g/l PEG in MS medium, the highest shoot number was in Suluhna genotype (4.33) followed by Gerao (3.67). The highest shoot length was in Suluhna (2.11 cm) with no significant difference with Gerao (2.02 cm). Root number (5.00 and root length (1.41 cm) were in the genotype Suluhna. Survival percentage of in vitro regenerated plantlets was 100% during hardening. By taking into consideration, all the growth parameter tested revealed that Suluhna, Gerao, Limo and Lemats Beles showed better drought stress tolerance at the highest level of PEG while Keyih Beles and Shenkor appeared to be drought sensitive at the highest level of PEG.

Physico-chemical Properties of Sesame (<i>Sesamum indicum</i>L.) Varieties Grown in Northern Area, Ethiopia

This study was conducted to evaluate the physico-chemical properties of three sesame varieties: Adi, Bawnji and T-85. Sesame varieties showed significant (p ≤ 0.05) differences on some physical properties, proximate, mineral, anti-nutritional (phytic acid) and antioxidant compositions. The average values of 1000 seed weight were ranged from (2.74 - 3.16 g) and true density from (1190.66 to 1215.58 kg m-3). The moisture (wb), crude protein, ash, fat, fiber, total carbohydrate, Ca, Zn and Fe (db) were ranged: 3.17% - 3.96%, 22.58% - 24.27%, 4.46% - 6.19%, 50.88% - 52.67%, 5.60% - 6.26%, 8.3% - 11.69%, 1172.08 - 1225.71 mg/100g, 4.23 - 4.45 mg/100g and 10.2 - 10.75 mg/100g, respectively. Phytic acid contents were ranged from 307.61 to 324.91 mg/100g, total phenolics from (23.16 - 25.69 mg GAE/g) and ferric ion reducing power value from (32.33 - 34.53 μmol/g) (db). The results were compared with some other sesame varieties grown worldwide. Results showed that Ethiopian sesame varieties were good source in nutrients and were functional foods for human nutrition and utilization.

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.

Rehabilitation of indigenous browse plant species following exclosure established on communal grazing lands in South Tigray, Ethiopia, and implication for conservation

Background:Despite the wide use of indigenous browse plant species,there is almost no information on the rehabilitation of indigenous browse species following area exclosure(AE)established on communal grazing lands(CGL)in Southern Tigray.The objectives of this study were to assess the rehabilitation of browse plant species following AE establishment on CGL.A total of 61 and 59 plots of 10×10m2 size were laid down at 50-m intervals along parallel line transects at AE and GCL,respectively.Data collected on vegetation attributes were subjected to analysis of t test(unequal variances)using R-software.Results:The Shannon diversity index of the browse plant species was 1.25 and 0.81 in AE and CGL,respectively(P<0.001).The overall population structure of browse plant species in the AE shows a reverse J-shaped population curve and“good”regeneration status,which reveals that the future communities may be sustained.Leaf biomass and basal area of browse plant species were significantly higher in the AE than in CGL(P<0.001).After exclusion of grazing,AE was found to have positive effects on diversity and aboveground biomass of browse plant species.Conclusions:The study gives an understanding of the diversity,the pattern of population and regeneration of the browse plant species,which may help in the management and conservation of the species.Our results indicate that grazing exclusion is an effective management strategy to restore browse plant species.We concluded that the establishment of AE had a positive effect on the rehabilitation of browse plant species diversity and improved population structure and regeneration potentials of degraded grazing lands.Long-term monitoring and evaluation systems will be required to gain an informed understanding of the roles played by area exclosures in the rehabilitation and conservation of browse palnt species diversity.

Effect of Senna obtusifolia(L.)invasion on herbaceous vegetation and soil properties of rangelands in the western Tigray,northern Ethiopia

Introduction:Invasion of exotic plant species is a well-known threat to native ecosystems since it directly affects native plant communities by altering their composition and diversity.Moreover,exotic plant species displace native species through competition,changes in ecosystem processes,or allelopathic effects.Senna obtusifolia(L.)invasion has affected the growth and productivity of herbaceous vegetation in semi-arid regions of northern Ethiopia.Here,we investigated the species composition,species diversity,aboveground biomass,and basal cover of herbaceous vegetation,as well as soil properties of rangelands along three S.obtusifolia invasion levels.Methods:Herbaceous vegetation and soil properties were studied at two locations,Kafta Humera and Tsegede districts,in the western Tigray region of northern Ethiopia under three levels of S.obtusifolia invasion,i.e.,non-invaded,lightly invaded,and heavily invaded.Herbaceous plant species composition and their abundance were assessed using a 1-m^(2) quadrat during the flowering stage of most herbaceous species from mid-August to September 2015.Native species were classified into different functional groups and palatability classes,which can be useful in understanding mechanisms underlying the differential responses of native plants to invasion.The percentage of basal cover for S.obtusifolia and native species and that of bare ground were estimated in each quadrat.Similar to sampling of the herbaceous species,soil samples at a depth of 0–20 cm were taken for analyzing soil physical and chemical properties.Results:Highly palatable grasses and legumes based on the frequency of occurrence were 1.9 and 3.8 times higher in non-invaded sites than in lightly and heavily invaded sites,respectively.Furthermore,unpalatable plant species were 4.0 times higher in the heavily invaded sites than in the lightly invaded sites.Aboveground biomass,basal cover,and species diversity of the herbaceous vegetation were significantly(P<0.01)lower in the heavily invaded sites compared to the non-invaded sites.However,most soil properties were not affected by S.obtusifolia invasion compared with non-invaded sites in our study.Conclusions:Our findings contribute towards better understanding of how S.obtusifolia invasion affects the community structure and composition of native herbaceous vegetation in semi-arid rangelands in northern Ethiopia.Further long-term studies are required to understand the mechanisms of how S.obtusifolia invasion influences soil properties for better control and eradication of its invasion in the semi-arid rangelands of northern Ethiopia.

Exclosure land management for restoration of herbaceous species in degraded communal grazing lands in Southern Tigray

Herbaceous species contribute to the largest proportion of the fodder.Despite the profound benefits obtained,anthropogenic disturbances are hindering its development.On the other hand,to ensure the sustainability of herbaceous species,communities and governments have been putting efforts in managing herbaceous species through the establishment of area exclosure(AE).Thus,the main importance of this research paper is to provide information about the role of AE on the restoration of herbaceous species.The objective of this study was to assess the effect of restoration on the herbaceous species following AE established on communal grazing land(CGL).A total of 124 and 73 quadrats of 1×1m^(2) size were laid down at 50 m intervals along parallel transects at AE and CGL,respectively,and data were analyzed by t-test unequal variances using R-software.AE displayed higher plant species richness and diversity than the CGL and showed a significant difference(p<0.001).Similarly,the AE had significantly(p<0.001)higher forage biomass than the CGL.In general,herbaceous species diversity index and species richness were significantly(p<0.001)higher in the AE compared to the CGL.The study concluded that effective AE has the potential to enhance the restoration of herbaceous species and hence forage productivity.

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.

Variation in Plant Morphology and Sinigrin Content in Ethiopian Mustard(Brassica carinata L.)

Ethiopian mustard(Brassica carinata) is mainly grown as a leafy vegetable and oilseed crop. Sinigrin is predominant glucosinolate in the leaves of Ethiopian mustard. It is hydrolyzed by enzyme myrosinase to produce bioactive product specifically allyl-isothiocyanates. Due to sinigrin content, Ethiopian mustard has a mild flavor and it is a healthy addition to human diet. However, sinigrin concentration depends on genotype.Understanding variations of plant morphology and sinigrin content may be the first step for crop improvement. According to the analyses of various plant characteristics among ninety nine Ethiopian mustard accessions, we found significant differences in plant height, chlorophyll content, and petiole length. In addition, sinigrin content was determined using ultra-performance liquid chromatography tandem quadrupole mass spectrometers/tunable ultraviolet detector(UPLC-TQS/TUV). We found a significant difference in sinigrin content among leaves of 94 Ethiopian mustard accessions. Except for petiole length, the sinigrin content was negatively correlated with leaf area, leaf width, number of primary branches, and plant height. This information will help Ethiopian mustard breeders in screening breeding lines for new accessions.

Evaluation of Global Gridded Precipitation and Temperature Datasets against Gauged Observations over the Upper Tekeze River Basin,Ethiopia

The availability of satellite and reanalysis climate datasets and their applicability have been greatly promoted in hydro-climatic studies.However,such climatic products are still subject to considerable uncertainties and an evaluation of the products is necessary for applications in specific regions.This study aims to evaluate the reliability of nine gridded precipitation and temperature datasets against ground-based observations in the upper Tekeze River basin(UTB)of Ethiopia from 1982 to 2016.Precipitation,maximum temperature(Tmax),minimum temperature(Tmin),and mean temperature(Tmean)were evaluated at daily and monthly timescales.The results show that the best estimates of precipitation are from the Eart H2 Observe,WFDEI,and ERA-Interim reanalysis data Merged and Bias-corrected for the Inter-Sectoral Impact Model Intercomparison Project(EWEMBI),and the Climate Hazards Group Infra Red Precipitation with Station data(CHIRPS)datasets.The percentage biases and correlation coefficients(CCs)are within±15%and>0.5,respectively,for both EWEMBI and CHIRPS at the two timescales.All products underestimate the drought conditions indicated by the standardized precipitation index(SPI),while the EWEMBI and CHIRPS datasets show higher agreement with the observations than other datasets.The Tmean estimates produced by the ECMWF ReAnalysis version 5(ERA5)and the Climate Hazards Group Infra Red Temperature with Station data(CHIRTS)are the closest to the observations,with CCs of 0.65 and 0.55,respectively,at the daily timescale.The CHIRTS and EWEMBI datasets show better representations of Tmax(T_(min)),with CCs of 0.69(0.72)and 0.62(0.68),respectively,at the monthly timescale.The temperature extremes are better captured by the ERA5(T_(mean)),CHIRTS(T_(max)),and EWEMBI(T_(min))datasets.The findings of this study provide useful information to select the most appropriate dataset for hydrometeorological studies in the UTB and could help to improve the regional representation of global datasets.

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.

Coupling remote sensing and crop growth model to estimate national wheat yield in Ethiopia

Estimation of crop yield at a regional level is essential for making agricultural planning and addressing food security issues in Ethiopia.Remote sensing observations,particularly the leaf area index(LAI),have a strong relationship with crop yield.This study has proposed an approach to estimate wheat yield at field level and regional scale in Ethiopia by assimilating the retrieved MODIS time-series LAI data into the WOrld FOod STudies(WOFOST)model.To improve the estimation of crop yield in the region,the Ensemble Kalman Filter(EnKF)was used to incorporate the LAI into the WOFOST model.The estimation accuracy of wheat crop yield was validated using field-measured yields collected during the 2018 growing season.Our findings indicated that wheat yield was more precisely estimated by WOFOST(at water-limited mode)with EnKF algorithm(R^(2)=0.80 and RMSE=413 kg ha^(−1))compared to that of without assimilating remotely sensed LAI(R^(2)=0.58,RMSE=592 kg ha^(−1)).These results demonstrated that assimilating MODIS-LAI into WOFOST has high potential and practicality to give a reference for wheat yield estimation.The findings from this study can provide information to policy,decision-makers,and other similar sectors to implement an appropriate and timely yield estimation measure.