The relationship between the fate of nitrogen (N) fertilizer and the N application rate in paddy fields in Northeast China is unclear,as is the fate of residual N.To clarify these issues,paddy field and15N microplot e...The relationship between the fate of nitrogen (N) fertilizer and the N application rate in paddy fields in Northeast China is unclear,as is the fate of residual N.To clarify these issues,paddy field and15N microplot experiments were carried out in 2017 and 2018,with N applications at five levels:0,75,105,135 and 165 kg N ha–1(N0,N75,N105,N135 and N165,respectively).15N-labeled urea was applied to the microplots in 2017,and the same amount of unlabeled urea was applied in 2018.Ammonia (NH3) volatilization,leaching,surface runoff,rice yield,the N contents and15N abundances of both plants and soil were analyzed.The results indicated a linear platform model for rice yield and the application rate of N fertilizer,and the optimal rate was 135 kg N ha–1.N uptake increased with an increasing N rate,and the recovery efficiency of applied N (REN) values of the difference subtraction method were 45.23 and 56.98%on average in 2017and 2018,respectively.The RENwas the highest at the N rate of 135 kg ha–1in 2017 and it was insignificantly affected by the N application rate in 2018,while the agronomic efficiency of applied N (AEN) and physiological efficiency of applied N (PEN) decreased significantly when excessive N was applied.N loss through NH3volatilization,leaching and surface runoff was low in the paddy fields in Northeast China.NH3volatilization accounted for 0.81 and 2.99%of the total N application in 2017 and 2018,respectively.On average,the leaching and surface runoff rates were 4.45% and less than 1.05%,respectively,but the apparent denitrification loss was approximately 42.63%.The residual N fertilizer in the soil layer (0–40 cm) was 18.37–31.81 kg N ha–1in 2017,and the residual rate was 19.28–24.50%.Residual15N from fertilizer in the soil increased significantly with increasing N fertilizer,which was mainly concentrated in the 0–10 cm soil layer,accounting for 58.45–83.54% of the total residual N,and decreased with increasing depth.While the ratio of residual N in the 0–10 cm soil layer to that in the 0–40 cm soil layer was decreased with increasing N application.Furthermore,of the residual N,approximately 5.4%was taken up on average in the following season and 50.2%was lost,but 44.4%remained in the soil.Hence,the amount of applied N fertilizer should be reduced appropriately due to the high residual N in paddy fields in Northeast China.The appropriate N fertilizer rate in the northern fields in China was determined to be 105–135 kg N ha–1in order to achieve a balance between rice yield and high N fertilizer uptake.展开更多
This comprehensive review focuses on the performance of solar dryers, with a specific emphasis on their structural shape and orientation. Researchers have extensively examined these design parameters, often employing ...This comprehensive review focuses on the performance of solar dryers, with a specific emphasis on their structural shape and orientation. Researchers have extensively examined these design parameters, often employing Computational Fluid Dynamics (CFD) to assess thermal attributes and predict temperature distribution, airflow patterns, and temperature profiles within the structures. Geographical location significantly influences solar dryer shape preferences, with the parabolic shape finding favor in tropical regions for its superior solar radiation capture and storm resistance, while even-span and Quonset shapes are popular elsewhere. Solar dryer orientation is another crucial factor, with east-west alignment consistently proving optimal due to its ability to maximize year-round solar radiation absorption and, consequently, enhance drying efficiency. Economic considerations, however, fall beyond the scope of this review, which predominantly focuses on thermal aspects. This investigation reveals diverse global preferences for solar dryer shapes and orientation, highlighting the necessity of considering geographical factors in design choices. While CFD and shape/orientation dynamics have provided valuable insights, there remains room for future research to expand into transient state simulations under various conditions, contributing to a more comprehensive understanding of solar dryer performance. Such insights promise to promote sustainable and efficient drying processes, benefitting agricultural and drying applications across the globe.展开更多
Nitrogen(N)supply is the most important factor affecting yield and quality of flue-cured tobacco(FCT).A field experiment and an in situ incubation method were used to study the effects of soil N mineralization in the ...Nitrogen(N)supply is the most important factor affecting yield and quality of flue-cured tobacco(FCT).A field experiment and an in situ incubation method were used to study the effects of soil N mineralization in the later stages of growth on yield and nicotine content of FCT in Fenggang and Jinsha,Guizhou Province.The yield and market value of FCT at Fenggang were much lower than those at Jinsha.However,the nicotine content of middle and upper leaves was much higher at Fenggang than at Jinsha when the same rate of fertilizer N was applied,which might be due to a higher N supply capacity at the Fenggang site.At later stages of growth(7-16 weeks after transplanting),the soil net N mineralization at Fenggang(56 kg N ha^(-1))was almost double that at Jinsha(30 kg N ha^(-1)).While soil NH_4-N and NO_3-N were almost exhausted by the plants or leached 5 weeks after transplanting,the N taken up at the later growth stages at Fenggang were mainly derived from soil N mineralization,which contributed to a high nicotine content in the upper leaves.The order of soil N contribution to N buildup in different leaves was:upper leaves>middle leaves>lower leaves.Thus,soil N mineralization at late growth stages was an important factor affecting N accumulation and therefore the nicotine content in the upper leaves.展开更多
Balancing ecological preservation with sustainable agricultural practices is a global issue. Erhai Lake has felt this challenge keenly. To address it, in 2022, a Science and Technology Backyards(STBs) project was laun...Balancing ecological preservation with sustainable agricultural practices is a global issue. Erhai Lake has felt this challenge keenly. To address it, in 2022, a Science and Technology Backyards(STBs) project was launched in Gusheng Village. The goal of this is to care for the environment while ensuring that farms and farmers can thrive sustainably. The uniqueness of the Erhai STB arises from its interdisciplinary integration, encompassing fields such as ecology, agronomy and social science, resulting in specifically-designed solutions for the Erhai context. While this model aligns with broader STB paradigms, its distinctive edge lies in technological innovation and robust support mechanisms for local agricultural stakeholders. This paper describes the methodology and outcomes of the STB initiative, highlighting its pivotal role in spearheading sustainable transition in Erhai. Preliminary findings underscore the potential of the STB model as an efficacious tool for harmonizing environmental conservation and agricultural practices, that are both financially and environmentally sustainable, rendering it a potential model for comparable regions in China and other counties.展开更多
The rapidly growing demand for food, feed and fuel requires further improvements of land and water management, crop productivity and resource-use efficiencies.Combined field experimentation and crop growth modelling d...The rapidly growing demand for food, feed and fuel requires further improvements of land and water management, crop productivity and resource-use efficiencies.Combined field experimentation and crop growth modelling during the past five decades made a great leap forward in the understanding of factors that determine actual and potential yields of monocrops.The research field of production ecology developed concepts to integrate biological and biophysical processes with the aim to explore crop growth potential in contrasting environments.To understand the potential of more complex systems(multi-cropping and intercropping) we need an agro-ecosystem approach that integrates knowledge derived from various disciplines: agronomy, crop physiology, crop ecology, and environmental sciences(soil, water and climate).Adaptation of cropping systems to climate change and a better tolerance to biotic and abiotic stresses by genetic improvement and by managing diverse cropping systems in a sustainable way will be of key importance in food security.To accelerate sustainable intensification of agricultural production, it is required to develop intercropping systems that are highly productive and stable under conditions with abiotic constraints(water, nutrients and weather).Strategies to achieve sustainable intensification include developing tools to evaluate crop growth potential under more extreme climatic conditions and introducing new crops and cropping systems that are more productive and robust under conditions with abiotic stress.This paper presents some examples of sustainable intensification management of intercropping systems that proved to be tolerant to extreme climate conditions.展开更多
Size and shape are important properties of shrub crops such as blueberries,and they can be particularly useful for evaluating bush architecture suited to mechanical harvesting.The overall goal of this study was to dev...Size and shape are important properties of shrub crops such as blueberries,and they can be particularly useful for evaluating bush architecture suited to mechanical harvesting.The overall goal of this study was to develop a 3D imaging approach to measure size-related traits and bush shape that are relevant to mechanical harvesting.3D point clouds were acquired for 367 bushes from five genotype groups.Point cloud data were preprocessed to obtain clean bush points for characterizing bush architecture,including bush morphology(height,width,and volume),crown size,and shape descriptors(path curveλand five shape indices).One-dimensional traits(height,width,and crown size)had high correlations(R^(2)=0.88–0.95)between proposed method and manual measurements,whereas bush volume showed relatively lower correlations(R^(2)=0.78–0.85).These correlations suggested that the present approach was accurate in measuring one-dimensional size traits and acceptable in estimating three-dimensional bush volume.Statistical results demonstrated that the five genotype groups were statistically different in crown size and bush shape.The differences matched with human evaluation regarding optimal bush architecture for mechanical harvesting.In particular,a visualization tool could be generated using crown size and path curveλ,which showed great potential of determining bush architecture suitable for mechanical harvesting quickly.Therefore,the processing pipeline of 3D point cloud data presented in this study is an effective tool for blueberry breeding programs(in particular for mechanical harvesting)and farm management.展开更多
A rice residual heterozygous line(RHL) carrying a heterozygous segment extending from RM111 to RM19784 on the short arm of rice chromosome 6 was selected from a RHL-derived population used previously.The resultant F2:...A rice residual heterozygous line(RHL) carrying a heterozygous segment extending from RM111 to RM19784 on the short arm of rice chromosome 6 was selected from a RHL-derived population used previously.The resultant F2:3 population was used to detect quantitative trait loci(QTLs) for three yield traits,the number of spikelets per panicle(NSP),the number of grains per panicle(NGP) and grain yield per plant(GY).Two QTLs for NSP,one QTL for NGP and one QTL for GY were detected,all of which were partially dominant and had the enhancing alleles from the maternal line Zhenshan 97B.Analysis based on the genotypic groups of the markers closely linked to the two QTLs for NSP indicated that they did not interact with each other.Two F2 populations and two near isogenic line(NIL) sets segregating in two sub-regions of interval RM111-RM19784 were developed.The two QTLs for NSP were validated,of which one had major effect and was co-segregated with heading date gene Hd1,and the other had smaller effect and was located in an upper region linked to Hd1.The two regions also showed significant effects on the number of filled grain and grain yield,although the effect on the number of filled grain was less consistent.展开更多
Smallholder farmers in Namutumba district draw on a combination of adaptation strategies to respond to effects of climate variability. However, there is limited scholarly evidence and explanation that has been conduct...Smallholder farmers in Namutumba district draw on a combination of adaptation strategies to respond to effects of climate variability. However, there is limited scholarly evidence and explanation that has been conducted on the factors that influence the choice of alternative sets of strategies that smallholder farmers use in response to climate variability specific stress and literature that disentangles climatic stressors specific adaptation options. A multi-stage sampling procedure was employed to select the study area and household respondents. The study used cross-sectional research design to collect both quantitative and qualitative data. Household data was collected from 160 respondents with a structured questionnaire supported by key informant interviews. Multinomial logit modeling (MNL) was used to determine the relative influence of selected household socio-demographic factors on the choice of adaptation strategies against the dry spell. Principal Components Analysis (PCA) was used to create weighted adaptation index for categorizing various similar adaptation strategies. In order to respond to the impact of climate variability stresses, smallholder farmers have adapted growing drought-resistant crops (12.2%), extension of the agricultural frontier into wetlands during the dry spells (37%), whereas use of crop rotation (9.8%) is the most dominant strategies used to manage pest and diseases, similarly soil and water conservation (15.3%) and climate-smart planning basin (11%) are the most dominant adaptation strategies use to manage flood. Empirical results from multinomial logit modeling showed that predictor variables gender, level of education, years of farming, house size, access to credit, and own radio have a significant influence on the choice of adaptation strategies with differences significant level during the dry spell. The study recommends that future policies should focus on strengthening the existing extension training package, strengthening the existing farmer’s groups and cooperatives, encouraging informal social networks in order to boost smallholder farmers’ adaptation to climate variability.展开更多
Community garden is a popular vegetation landscape mode with production,ecology and life functions. On the basis of eco-service functions of community garden,this paper selected 14 such gardens in Los Angeles and stud...Community garden is a popular vegetation landscape mode with production,ecology and life functions. On the basis of eco-service functions of community garden,this paper selected 14 such gardens in Los Angeles and studies them by field survey. It researched the response of diversity of urban vegetation varieties and distribution pattern to planters' ethnic background and construction mode,then it analyzed its implications for China's urban green space construction and leisure agriculture. A total of 439 varieties of plant were studied,indicating that community garden is an important species pool of urban ecosystem; it can maintain rich native taxa resources; plant function is mainly edible plant, which plays a great role in protecting ethnic traditional culture and regional native culture; landscape structure and function of vegetation are influenced by ethnic background and construction mode. Researches show that the community garden,as the intersection landscape of ecological diversity and cultural diversity,is a feasible construction mode for realizing urban green infrastructure construction and leisure agricultural development. China should learn from this experience,take into consideration interested parties when making green space planning and conducting eco-vegetation construction. This is of great significance to launching urban eco-vegetation construction and developing leisure agriculture in China.Community garden is a popular vegetation landscape mode with production,ecology and life functions. On the basis of eco-service functions of community garden,this paper selected 14 such gardens in Los Angeles and studies them by field survey. It researched the response of diversity of urban vegetation varieties and distribution pattern to planters' ethnic background and construction mode,then it analyzed its implications for China's urban green space construction and leisure agriculture. A total of 439 varieties of plant were studied,indicating that community garden is an important species pool of urban ecosystem; it can maintain rich native taxa resources; plant function is mainly edible plant, which plays a great role in protecting ethnic traditional culture and regional native culture; landscape structure and function of vegetation are influenced by ethnic background and construction mode. Researches show that the community garden,as the intersection landscape of ecological diversity and cultural diversity,is a feasible construction mode for realizing urban green infrastructure construction and leisure agricultural development. China should learn from this experience,take into consideration interested parties when making green space planning and conducting eco-vegetation construction. This is of great significance to launching urban eco-vegetation construction and developing leisure agriculture in China.展开更多
Oil exploitation in many African countries is associated with litigation and conflicts to water and soil pollution. It is because of inadequate planning for management of oil spills and industrial effluents in environ...Oil exploitation in many African countries is associated with litigation and conflicts to water and soil pollution. It is because of inadequate planning for management of oil spills and industrial effluents in environmentally sustainable manner. Uganda’s natural resources such as soils and water bodies are threatened by contamination due to rapid industrialization and rural-urban migration in established Industrial Business Parks and planned oil and gas production at Albertine Graben Region. The low level of compliance to industrial effluents discharge standards relevant to specific environmental receptors and activities within oil and gas sector development pose a big question of how to sustain the biodiversity and natural resource management. Experiences from elsewhere have shown bioremediation as a viable and proven option to provide potentially manageable solutions to resulting pollution as a substitute to modern well-known remediation methods, for it is relatively cheaper, more efficient and minimal toxic byproducts after treatment. The most used bioremediation agents in different studies reviewed are bacterial species especially Pseudomonas and Bacillus, followed by Aspergillus a fungi species, microalgae and aquatic plants such as duckweed, macrophytes and pteridophytes. Regardless of the waste produced in either oil and gas sector or industries, these agents have shown greater biodegradation rates. Pseudomonas sp. has a degradation efficiency of oil compounds ranging from 90% - 100%, and Aspergillus sp. 75% - 95%. Some aquatic plants can thrive in created wetlands with relatively still water such as Phragmites australis which can degrade hydrocarbons especially Aromatic compounds with benzene ring up to 95%. It can thrive in salty water with high pH range of 4.8 - 8.2. With industrial wastewater, algae is the most dominant with the degradation rates varying from 65% -100% and bacteria at 70% - 90%. Most of the reported results are in the developed country context. In developing countries, duckweed is reported as the commonest aquatic plant in wastewater treatment for removal of heavy metals because it is more tolerant to a wide range of environmental conditions and produce biomass faster. It has a removal rate of heavy metals between 90% and 100%. Basing on literature data analysis, bacteria are more suitable for treating water from oil pollution using Pseudomonas sp. Phragmites australis is suited for cleaning up oil in both water and soil. Duckweed is the best in treating water polluted with industrial effluents. This paper presents the different bioremediation methods that Uganda can potentially apply to mitigate the increased risk of environmental pollutions from planned industrialization and oil and gas development in the Albertine Graben Region.展开更多
The study evaluated the productivity and energy balance of the harvesting and the extraction of wood in plantation of exotic tree species, i.e., Pinus patula (Schiede ex Schlectendahl et Chamisso) and Cupressus lusita...The study evaluated the productivity and energy balance of the harvesting and the extraction of wood in plantation of exotic tree species, i.e., Pinus patula (Schiede ex Schlectendahl et Chamisso) and Cupressus lusitanica (Mill.). The harvesting and extraction operations concerned clear-cut felling on two different types of terrain (gentle and steep terrain) and two levels of pruning. The results show that cutting is not affected by the terrain gradient whereas the pruning condition shows a significant effect on the delimbing operation. The productivity of cutting is evaluated at 28.1 m3·d-1 for unpruned trees and at 30.2 m3·d-1 for pruned trees. For the extraction phase, rolling was significantly affected by terrain conditions. On steep terrain, the gross productivity can be evaluated at 22.5 m3·d-1 for an extraction distance of 40 m, while for the same distance on gentle terrain the productivity decreases to 14.1 m3·d-1 . As a result, the steep terrain condition showed higher energy efficiency, suggesting that it is the more efficient system of extraction. The productivity model and the energy balance resulting from the study provide a better understanding of the variables affecting motor-manual cutting and rolling extraction in exotic plantations in Uganda.展开更多
The cultural universe is sometimes confusing,surprising and murky,so many cultural maps get drawn,discussed and envisioned.A study was undertaken around Mabira Forest Reserve in central Uganda to identify the trees an...The cultural universe is sometimes confusing,surprising and murky,so many cultural maps get drawn,discussed and envisioned.A study was undertaken around Mabira Forest Reserve in central Uganda to identify the trees and shrubs culturally managed on-farm,assess the cultural practices of forest and tree system management and determine the relationship between farmer gender and forest and tree system management.We engaged 203 farmers in focus group discussions and semi-structured interviews to collect data.Qualitative data were jointly evaluated with farmers;quantitative data were analyzed in SPSS 20.0.The results showed a high likelihood for involvement of local people in tree or forest management for economic gain,as timber and fast-growing species were highly ranked.Food and medicinal species were also regarded as important,suggesting high prospects of integrating them into the local farming system or protecting them in the forest.Numerous cultural practices(including rituals,trenching,bark slashing,ring barking,spot weeding and use of organic manure and pesticides)of forest and tree system management were acknowledged.However,their knowledge was mixed and unclear about distinct cultural and supportive arrangements for natural forest and tree restoration.While gender was not a significant cultural attribute for knowledge of the forest and allied tree system management,age substantially affected farmer propensity for various timber products.Also farmer’s family size influenced the collection of tree wildings and fodder.We encourage considering gender disparities and livelihood needs including income,during selection of cultural practices for forest and tree restoration.展开更多
Children in resource poor settings are at a high risk of inadequate iron and vitamin A intake when diets lack diversity and are dominated by staple foods. Yet comparative information on diet quality among school child...Children in resource poor settings are at a high risk of inadequate iron and vitamin A intake when diets lack diversity and are dominated by staple foods. Yet comparative information on diet quality among school children is scarce. The objective of the study was to assess the potential of simple food group diversity to serve as a proxy indicator of iron and vitamin A status among rural school children in Uganda. A cross sectional correlation model of associations between Food Group Diversity (FGD) and iron and vitamin A status was used. We analyzed 8 schools in Kumi District, Uganda, randomly selected from the 34 schools that participated in the main part of the study. Our sample included primary school children, aged between 9-15 years (n = 172). Food group diversity and food variety (FV) were calculated from both a food frequency questionnaire (FFQ) and a 24-hour dietary recall. The FGD and FVS were tested against iron (as serum ferritin) and vitamin A (as serum retinol) status. The FGD (based on FFQ data) was 9.6 (±1.9). There was a positive correlation between 24-hour recall and FFQ for consumption of cereals (Corr. Coef = 0.28;p 0.05), which was also the most highly consumed group (98.9% & 86.9% by FFQ and 24-hour recall;respectively). Consistent with other studies, increase in the number of food groups significantly increased serum ferritin and serum retinol measures (p 0.001). Presence of at least one food item in the “roots & tubers”;“cereals”;and “pulses/nuts”, significantly increased serum ferritin and serum retinol concentrations (p 0.01). We speculate that simple food group diversity may reflect intake and serve as a simple indicator of iron and vitamin A status among school children. Strategies aimed at increasing dietary diversity in the community may benefit the families of these children and improve their micronutrient status.展开更多
Striga hermonthica(Del.)Benth is ranked as the number one constraint to maize productivity in Eastern Uganda.The use of trap crops is one of the control measures suggested for farmers with limited resources in Striga ...Striga hermonthica(Del.)Benth is ranked as the number one constraint to maize productivity in Eastern Uganda.The use of trap crops is one of the control measures suggested for farmers with limited resources in Striga infested areas.In this study the main focus was on the effectiveness of intercropping in reducing Striga infestation and hence overall land productivity.The major objective was to identify suitable legumes in the control of Striga.In order to achieve this,on-farm experiments were conducted in Tororo and Busia districts of Eastern Uganda where the effect of the legumes on the Striga prevalence was evaluated.Maize(Zea mays)was intercropped with common beans(Phaseolus vulgaris),soybean(Glycine max)and silver leaf desmodium(Desmodium uncinatum)with sole maize(Z.mays)as the control.Soybean,beans and desmodium decreased the infestation of Striga by 26%,40%and 72%,respectively.There was a significant(p<0.05)difference in the number of emerged Striga and maize yield attained by desmodium and the rest of the legumes.Desmodium was found to be the most effective of the legumes in the control of Striga.展开更多
Sorghum’s natural adaptation to a wide range of abiotic stresses provides diverse genetic reserves for potential improvement in crop stress tolerance. Growing interest in sorghum research has led to the expansion of ...Sorghum’s natural adaptation to a wide range of abiotic stresses provides diverse genetic reserves for potential improvement in crop stress tolerance. Growing interest in sorghum research has led to the expansion of genetic resources though establishment of the sorghum association panel (SAP), generation of mutagenized populations, and recombinant inbred line (RIL) populations</span><span style="font-family:Verdana;">,</span><span style="font-family:Verdana;"> etc. Despite rapid improvement in biotechnological tools, lack of efficient phenotyping platforms remains one of the major obstacles in utilizing these genetic resources. Scarcity of efforts in root system phenotyping hinders identification and integration of the superior root traits advantageous to stress tolerance. Here, we explored multiple approaches in root phenotyping of an ethyl methanesulfonate (EMS)-mutagenized sorghum population. Paper-based growth pouches (PGP) and hydroponics were employed to analyze root system architecture (RSA) variations induced by mutations and to test root development flexibility in response to phosphorus deficiency in early growing stages. PGP method had improved capabilities compared to hydroponics providing inexpensive, space-saving, and high-throughput phenotyping of sorghum roots. Preliminary observation revealed distinct phenotypic variations which were qualitatively and quantitatively systemized for association analysis. Phenotypes/ideotypes with root architecture variations potentially correlated with Pi acquisition were selected to evaluate their contribution to P-efficiency (PE). Sand mixed with P-loaded activated alumina substrate (SAS) provided closely to natural but still controlled single-variable conditions with regulated Pi availability. Due to higher labor and cost input we propose SAS to be used for evaluating selected sorghum candidates for PE. The ability of rapidly screening root phenotypes holds great potential for discovering genes responsible for relevant root traits and utilizing mutations to improve nutrient efficiency and crop productivity.展开更多
Alfalfa (Medicago sativa L.) is an important forage and conservation crop in North America but occurrences of naturalized alfalfa in rangelands are rare. A naturalized population of yellow-flowered alfalfa in mixed-gr...Alfalfa (Medicago sativa L.) is an important forage and conservation crop in North America but occurrences of naturalized alfalfa in rangelands are rare. A naturalized population of yellow-flowered alfalfa in mixed-grass prairie on the Grand River National Grassland in South Dakota has potential agricultural value for the region. Despite this value, the distribution pattern of this alfalfa among and within native plant communities in the northern Great Plains is unknown. Field studies were conducted from 2003 through 2006 along topographic positions at two sites where yellow-flowered alfalfa was naturalized to evaluate the relationships of yellow-flowered alfalfa on biomass production, cover, species diversity, and alfalfa seedbank distribution characteristics. High yellow-flowered alfalfa cover (>50%) was associated with increased total biomass and occurred exclusively in swales and toeslopes that had silty loam soils. However, species diversity and non-alfalfa biomass were reduced when yellow-flowered alfalfa cover was high. Yellow-flowered alfalfa cover was lower and species richness was higher on backslopes and shoulder areas where sandy loam soils were present. A strong positive linear association existed between yellow-flowered alfalfa cover and alfalfa seedbank density (r values ranged from 0.76 to 0.82, P < 0.0001). Greater than 99% of the seeds were viable but germination rate was only 4%, indicating a high percentage of hard seed in this alfalfa population. Naturalized yellow-flowered alfalfa was a dominant component of a stable, low diversity plant community composed of mainly introduced species in rich soils of swales/toeslopes that contributed to forage production and quality in mixed-grass prairie in the northern Great Plains.展开更多
Access to information and appropriate fishing gear is fundamental to the protection and conservation of the fisheries resources to guarantee sustainable livelihood of the fishers. Social networks in eight fishing sett...Access to information and appropriate fishing gear is fundamental to the protection and conservation of the fisheries resources to guarantee sustainable livelihood of the fishers. Social networks in eight fishing settlements of Rivers State were purposively selected to assess the role of networks on access and use of information and gear among the shrimp fishers. The cross-sectional study used mixed methods to elicit data. Data obtained were subjected to content analysis and MAXQDA 2018 software to generate project maps showing information and fishing gear accessed and used. Results show that 24.8%(31) of respondents joined social network due to information sharing behavior of network members. Information was shared through one-on-one interactions, group meetings, fish buyers and phone calls. Out of the 96.8%(121) of respondents belonging to shrimp fishers’ network, 23.2% attended meetings for at least four times a month while 22.4% attended meetings for more than four times a month. Information shared bordered on price of shrimps, weather and tide, fishing grounds and traps, water level, timing of fishing and processing techniques. Respondents revealed that information shared in their networks was correct, adequate and timely. Fishing gear accessed and used proficiently was dragnet, cast net and beach seine. In all, the evidence from the interview responses suggests that networks play a key role in shrimp fishers’ access and use of information and fishing gear. Fishers are therefore, encouraged to be in one network or the other.展开更多
基金supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(XDA28100302)the earmarked fund for China Agriculture Research System (CARS-01-29)+2 种基金the National Key Research and Development Program of China(2017YFD0200104)the Fifth (2019) of ‘Young Talents’ Project of Northeast Agricultural University,Chinathe Open Program of Key Laboratory of Germplasm Enhancement,Physiology and Ecology of Food Crops in Cold Region,Ministry of Education,Northeast Agricultural University (CXSTOP2021009)。
文摘The relationship between the fate of nitrogen (N) fertilizer and the N application rate in paddy fields in Northeast China is unclear,as is the fate of residual N.To clarify these issues,paddy field and15N microplot experiments were carried out in 2017 and 2018,with N applications at five levels:0,75,105,135 and 165 kg N ha–1(N0,N75,N105,N135 and N165,respectively).15N-labeled urea was applied to the microplots in 2017,and the same amount of unlabeled urea was applied in 2018.Ammonia (NH3) volatilization,leaching,surface runoff,rice yield,the N contents and15N abundances of both plants and soil were analyzed.The results indicated a linear platform model for rice yield and the application rate of N fertilizer,and the optimal rate was 135 kg N ha–1.N uptake increased with an increasing N rate,and the recovery efficiency of applied N (REN) values of the difference subtraction method were 45.23 and 56.98%on average in 2017and 2018,respectively.The RENwas the highest at the N rate of 135 kg ha–1in 2017 and it was insignificantly affected by the N application rate in 2018,while the agronomic efficiency of applied N (AEN) and physiological efficiency of applied N (PEN) decreased significantly when excessive N was applied.N loss through NH3volatilization,leaching and surface runoff was low in the paddy fields in Northeast China.NH3volatilization accounted for 0.81 and 2.99%of the total N application in 2017 and 2018,respectively.On average,the leaching and surface runoff rates were 4.45% and less than 1.05%,respectively,but the apparent denitrification loss was approximately 42.63%.The residual N fertilizer in the soil layer (0–40 cm) was 18.37–31.81 kg N ha–1in 2017,and the residual rate was 19.28–24.50%.Residual15N from fertilizer in the soil increased significantly with increasing N fertilizer,which was mainly concentrated in the 0–10 cm soil layer,accounting for 58.45–83.54% of the total residual N,and decreased with increasing depth.While the ratio of residual N in the 0–10 cm soil layer to that in the 0–40 cm soil layer was decreased with increasing N application.Furthermore,of the residual N,approximately 5.4%was taken up on average in the following season and 50.2%was lost,but 44.4%remained in the soil.Hence,the amount of applied N fertilizer should be reduced appropriately due to the high residual N in paddy fields in Northeast China.The appropriate N fertilizer rate in the northern fields in China was determined to be 105–135 kg N ha–1in order to achieve a balance between rice yield and high N fertilizer uptake.
文摘This comprehensive review focuses on the performance of solar dryers, with a specific emphasis on their structural shape and orientation. Researchers have extensively examined these design parameters, often employing Computational Fluid Dynamics (CFD) to assess thermal attributes and predict temperature distribution, airflow patterns, and temperature profiles within the structures. Geographical location significantly influences solar dryer shape preferences, with the parabolic shape finding favor in tropical regions for its superior solar radiation capture and storm resistance, while even-span and Quonset shapes are popular elsewhere. Solar dryer orientation is another crucial factor, with east-west alignment consistently proving optimal due to its ability to maximize year-round solar radiation absorption and, consequently, enhance drying efficiency. Economic considerations, however, fall beyond the scope of this review, which predominantly focuses on thermal aspects. This investigation reveals diverse global preferences for solar dryer shapes and orientation, highlighting the necessity of considering geographical factors in design choices. While CFD and shape/orientation dynamics have provided valuable insights, there remains room for future research to expand into transient state simulations under various conditions, contributing to a more comprehensive understanding of solar dryer performance. Such insights promise to promote sustainable and efficient drying processes, benefitting agricultural and drying applications across the globe.
基金the Program for Changjiang Scholars and Innovation Research Team in University(No.IRT0511)
文摘Nitrogen(N)supply is the most important factor affecting yield and quality of flue-cured tobacco(FCT).A field experiment and an in situ incubation method were used to study the effects of soil N mineralization in the later stages of growth on yield and nicotine content of FCT in Fenggang and Jinsha,Guizhou Province.The yield and market value of FCT at Fenggang were much lower than those at Jinsha.However,the nicotine content of middle and upper leaves was much higher at Fenggang than at Jinsha when the same rate of fertilizer N was applied,which might be due to a higher N supply capacity at the Fenggang site.At later stages of growth(7-16 weeks after transplanting),the soil net N mineralization at Fenggang(56 kg N ha^(-1))was almost double that at Jinsha(30 kg N ha^(-1)).While soil NH_4-N and NO_3-N were almost exhausted by the plants or leached 5 weeks after transplanting,the N taken up at the later growth stages at Fenggang were mainly derived from soil N mineralization,which contributed to a high nicotine content in the upper leaves.The order of soil N contribution to N buildup in different leaves was:upper leaves>middle leaves>lower leaves.Thus,soil N mineralization at late growth stages was an important factor affecting N accumulation and therefore the nicotine content in the upper leaves.
基金supported by the National Key R&D Program of China (2022YFD1901504-02)the Yunnan Science and Technology Program (202202AE090034-05) to Kemo Jin。
文摘Balancing ecological preservation with sustainable agricultural practices is a global issue. Erhai Lake has felt this challenge keenly. To address it, in 2022, a Science and Technology Backyards(STBs) project was launched in Gusheng Village. The goal of this is to care for the environment while ensuring that farms and farmers can thrive sustainably. The uniqueness of the Erhai STB arises from its interdisciplinary integration, encompassing fields such as ecology, agronomy and social science, resulting in specifically-designed solutions for the Erhai context. While this model aligns with broader STB paradigms, its distinctive edge lies in technological innovation and robust support mechanisms for local agricultural stakeholders. This paper describes the methodology and outcomes of the STB initiative, highlighting its pivotal role in spearheading sustainable transition in Erhai. Preliminary findings underscore the potential of the STB model as an efficacious tool for harmonizing environmental conservation and agricultural practices, that are both financially and environmentally sustainable, rendering it a potential model for comparable regions in China and other counties.
基金funded by the International Cooperation and Exchange of the National Science Foundation of China(31461143025,31210103906,51209220)the National Basic Research Program of China(973 Program,2011CB100405)the Special Fund for Agro-Scientific Research in the Public Interest,China(201003043)
文摘The rapidly growing demand for food, feed and fuel requires further improvements of land and water management, crop productivity and resource-use efficiencies.Combined field experimentation and crop growth modelling during the past five decades made a great leap forward in the understanding of factors that determine actual and potential yields of monocrops.The research field of production ecology developed concepts to integrate biological and biophysical processes with the aim to explore crop growth potential in contrasting environments.To understand the potential of more complex systems(multi-cropping and intercropping) we need an agro-ecosystem approach that integrates knowledge derived from various disciplines: agronomy, crop physiology, crop ecology, and environmental sciences(soil, water and climate).Adaptation of cropping systems to climate change and a better tolerance to biotic and abiotic stresses by genetic improvement and by managing diverse cropping systems in a sustainable way will be of key importance in food security.To accelerate sustainable intensification of agricultural production, it is required to develop intercropping systems that are highly productive and stable under conditions with abiotic constraints(water, nutrients and weather).Strategies to achieve sustainable intensification include developing tools to evaluate crop growth potential under more extreme climatic conditions and introducing new crops and cropping systems that are more productive and robust under conditions with abiotic stress.This paper presents some examples of sustainable intensification management of intercropping systems that proved to be tolerant to extreme climate conditions.
基金Project supported by the National Natural Science Foundation of China (No. 40201023)the Program for Changjiang Scholars and Innovative Research Team in University (IRT0412).
文摘在集中 of1,2,3,4,5,6-hexachlorocyclohexane ( HCH )和 l 的空间可变性， l ，l-trichloro-2,2-bis-( p-chloro-phenyl )乙烷( DDT ) insurface 土壤根据从北京的冲积区域的 thesurface 层( 0-20 厘米深度)收集的 131 件土壤样品的分析被学习， totalHCHs 的 China.The 集中(包括alpha-，贝它--，gamma-，和6异构体)并且全部的 DDT ( includingp ， p'-DDT ， p ， p'-DDD ， p ， p'-DDE ，和 o ， p'-DDT )在表面，测试的土壤在范围
基金supported by the USDA National Institute of Food and Agriculture Specialty Crop Research Initiative(Award No:2014-51181-22383).
文摘Size and shape are important properties of shrub crops such as blueberries,and they can be particularly useful for evaluating bush architecture suited to mechanical harvesting.The overall goal of this study was to develop a 3D imaging approach to measure size-related traits and bush shape that are relevant to mechanical harvesting.3D point clouds were acquired for 367 bushes from five genotype groups.Point cloud data were preprocessed to obtain clean bush points for characterizing bush architecture,including bush morphology(height,width,and volume),crown size,and shape descriptors(path curveλand five shape indices).One-dimensional traits(height,width,and crown size)had high correlations(R^(2)=0.88–0.95)between proposed method and manual measurements,whereas bush volume showed relatively lower correlations(R^(2)=0.78–0.85).These correlations suggested that the present approach was accurate in measuring one-dimensional size traits and acceptable in estimating three-dimensional bush volume.Statistical results demonstrated that the five genotype groups were statistically different in crown size and bush shape.The differences matched with human evaluation regarding optimal bush architecture for mechanical harvesting.In particular,a visualization tool could be generated using crown size and path curveλ,which showed great potential of determining bush architecture suitable for mechanical harvesting quickly.Therefore,the processing pipeline of 3D point cloud data presented in this study is an effective tool for blueberry breeding programs(in particular for mechanical harvesting)and farm management.
基金supported by the Chinese Super Rice Research Program(200906)the High-Yielding Transgenic Program,China(2008ZX08001-004)the National Natural Science Foundation of China(30571062)
文摘A rice residual heterozygous line(RHL) carrying a heterozygous segment extending from RM111 to RM19784 on the short arm of rice chromosome 6 was selected from a RHL-derived population used previously.The resultant F2:3 population was used to detect quantitative trait loci(QTLs) for three yield traits,the number of spikelets per panicle(NSP),the number of grains per panicle(NGP) and grain yield per plant(GY).Two QTLs for NSP,one QTL for NGP and one QTL for GY were detected,all of which were partially dominant and had the enhancing alleles from the maternal line Zhenshan 97B.Analysis based on the genotypic groups of the markers closely linked to the two QTLs for NSP indicated that they did not interact with each other.Two F2 populations and two near isogenic line(NIL) sets segregating in two sub-regions of interval RM111-RM19784 were developed.The two QTLs for NSP were validated,of which one had major effect and was co-segregated with heading date gene Hd1,and the other had smaller effect and was located in an upper region linked to Hd1.The two regions also showed significant effects on the number of filled grain and grain yield,although the effect on the number of filled grain was less consistent.
文摘Smallholder farmers in Namutumba district draw on a combination of adaptation strategies to respond to effects of climate variability. However, there is limited scholarly evidence and explanation that has been conducted on the factors that influence the choice of alternative sets of strategies that smallholder farmers use in response to climate variability specific stress and literature that disentangles climatic stressors specific adaptation options. A multi-stage sampling procedure was employed to select the study area and household respondents. The study used cross-sectional research design to collect both quantitative and qualitative data. Household data was collected from 160 respondents with a structured questionnaire supported by key informant interviews. Multinomial logit modeling (MNL) was used to determine the relative influence of selected household socio-demographic factors on the choice of adaptation strategies against the dry spell. Principal Components Analysis (PCA) was used to create weighted adaptation index for categorizing various similar adaptation strategies. In order to respond to the impact of climate variability stresses, smallholder farmers have adapted growing drought-resistant crops (12.2%), extension of the agricultural frontier into wetlands during the dry spells (37%), whereas use of crop rotation (9.8%) is the most dominant strategies used to manage pest and diseases, similarly soil and water conservation (15.3%) and climate-smart planning basin (11%) are the most dominant adaptation strategies use to manage flood. Empirical results from multinomial logit modeling showed that predictor variables gender, level of education, years of farming, house size, access to credit, and own radio have a significant influence on the choice of adaptation strategies with differences significant level during the dry spell. The study recommends that future policies should focus on strengthening the existing extension training package, strengthening the existing farmer’s groups and cooperatives, encouraging informal social networks in order to boost smallholder farmers’ adaptation to climate variability.
基金Supported by National Key Technology Research and Development Program of the Ministry of Science and Technology of China(2012BAJ24B05)Farmland Landscape Research Project of Beijing
文摘Community garden is a popular vegetation landscape mode with production,ecology and life functions. On the basis of eco-service functions of community garden,this paper selected 14 such gardens in Los Angeles and studies them by field survey. It researched the response of diversity of urban vegetation varieties and distribution pattern to planters' ethnic background and construction mode,then it analyzed its implications for China's urban green space construction and leisure agriculture. A total of 439 varieties of plant were studied,indicating that community garden is an important species pool of urban ecosystem; it can maintain rich native taxa resources; plant function is mainly edible plant, which plays a great role in protecting ethnic traditional culture and regional native culture; landscape structure and function of vegetation are influenced by ethnic background and construction mode. Researches show that the community garden,as the intersection landscape of ecological diversity and cultural diversity,is a feasible construction mode for realizing urban green infrastructure construction and leisure agricultural development. China should learn from this experience,take into consideration interested parties when making green space planning and conducting eco-vegetation construction. This is of great significance to launching urban eco-vegetation construction and developing leisure agriculture in China.Community garden is a popular vegetation landscape mode with production,ecology and life functions. On the basis of eco-service functions of community garden,this paper selected 14 such gardens in Los Angeles and studies them by field survey. It researched the response of diversity of urban vegetation varieties and distribution pattern to planters' ethnic background and construction mode,then it analyzed its implications for China's urban green space construction and leisure agriculture. A total of 439 varieties of plant were studied,indicating that community garden is an important species pool of urban ecosystem; it can maintain rich native taxa resources; plant function is mainly edible plant, which plays a great role in protecting ethnic traditional culture and regional native culture; landscape structure and function of vegetation are influenced by ethnic background and construction mode. Researches show that the community garden,as the intersection landscape of ecological diversity and cultural diversity,is a feasible construction mode for realizing urban green infrastructure construction and leisure agricultural development. China should learn from this experience,take into consideration interested parties when making green space planning and conducting eco-vegetation construction. This is of great significance to launching urban eco-vegetation construction and developing leisure agriculture in China.
文摘Oil exploitation in many African countries is associated with litigation and conflicts to water and soil pollution. It is because of inadequate planning for management of oil spills and industrial effluents in environmentally sustainable manner. Uganda’s natural resources such as soils and water bodies are threatened by contamination due to rapid industrialization and rural-urban migration in established Industrial Business Parks and planned oil and gas production at Albertine Graben Region. The low level of compliance to industrial effluents discharge standards relevant to specific environmental receptors and activities within oil and gas sector development pose a big question of how to sustain the biodiversity and natural resource management. Experiences from elsewhere have shown bioremediation as a viable and proven option to provide potentially manageable solutions to resulting pollution as a substitute to modern well-known remediation methods, for it is relatively cheaper, more efficient and minimal toxic byproducts after treatment. The most used bioremediation agents in different studies reviewed are bacterial species especially Pseudomonas and Bacillus, followed by Aspergillus a fungi species, microalgae and aquatic plants such as duckweed, macrophytes and pteridophytes. Regardless of the waste produced in either oil and gas sector or industries, these agents have shown greater biodegradation rates. Pseudomonas sp. has a degradation efficiency of oil compounds ranging from 90% - 100%, and Aspergillus sp. 75% - 95%. Some aquatic plants can thrive in created wetlands with relatively still water such as Phragmites australis which can degrade hydrocarbons especially Aromatic compounds with benzene ring up to 95%. It can thrive in salty water with high pH range of 4.8 - 8.2. With industrial wastewater, algae is the most dominant with the degradation rates varying from 65% -100% and bacteria at 70% - 90%. Most of the reported results are in the developed country context. In developing countries, duckweed is reported as the commonest aquatic plant in wastewater treatment for removal of heavy metals because it is more tolerant to a wide range of environmental conditions and produce biomass faster. It has a removal rate of heavy metals between 90% and 100%. Basing on literature data analysis, bacteria are more suitable for treating water from oil pollution using Pseudomonas sp. Phragmites australis is suited for cleaning up oil in both water and soil. Duckweed is the best in treating water polluted with industrial effluents. This paper presents the different bioremediation methods that Uganda can potentially apply to mitigate the increased risk of environmental pollutions from planned industrialization and oil and gas development in the Albertine Graben Region.
文摘The study evaluated the productivity and energy balance of the harvesting and the extraction of wood in plantation of exotic tree species, i.e., Pinus patula (Schiede ex Schlectendahl et Chamisso) and Cupressus lusitanica (Mill.). The harvesting and extraction operations concerned clear-cut felling on two different types of terrain (gentle and steep terrain) and two levels of pruning. The results show that cutting is not affected by the terrain gradient whereas the pruning condition shows a significant effect on the delimbing operation. The productivity of cutting is evaluated at 28.1 m3·d-1 for unpruned trees and at 30.2 m3·d-1 for pruned trees. For the extraction phase, rolling was significantly affected by terrain conditions. On steep terrain, the gross productivity can be evaluated at 22.5 m3·d-1 for an extraction distance of 40 m, while for the same distance on gentle terrain the productivity decreases to 14.1 m3·d-1 . As a result, the steep terrain condition showed higher energy efficiency, suggesting that it is the more efficient system of extraction. The productivity model and the energy balance resulting from the study provide a better understanding of the variables affecting motor-manual cutting and rolling extraction in exotic plantations in Uganda.
基金The work was supported by the European Union under the French Agricultural Research Center for International Development(CIRAD)through a project entitled"Forest Restoration in Degraded Forest Landscapes of Eastern Africa and Indian Ocean Islands"(FOREAIM),within the FP6 framework(International Cooperation-Developing Countries[INCO-DEV],Contract INCO-CT-2005-510790).
文摘The cultural universe is sometimes confusing,surprising and murky,so many cultural maps get drawn,discussed and envisioned.A study was undertaken around Mabira Forest Reserve in central Uganda to identify the trees and shrubs culturally managed on-farm,assess the cultural practices of forest and tree system management and determine the relationship between farmer gender and forest and tree system management.We engaged 203 farmers in focus group discussions and semi-structured interviews to collect data.Qualitative data were jointly evaluated with farmers;quantitative data were analyzed in SPSS 20.0.The results showed a high likelihood for involvement of local people in tree or forest management for economic gain,as timber and fast-growing species were highly ranked.Food and medicinal species were also regarded as important,suggesting high prospects of integrating them into the local farming system or protecting them in the forest.Numerous cultural practices(including rituals,trenching,bark slashing,ring barking,spot weeding and use of organic manure and pesticides)of forest and tree system management were acknowledged.However,their knowledge was mixed and unclear about distinct cultural and supportive arrangements for natural forest and tree restoration.While gender was not a significant cultural attribute for knowledge of the forest and allied tree system management,age substantially affected farmer propensity for various timber products.Also farmer’s family size influenced the collection of tree wildings and fodder.We encourage considering gender disparities and livelihood needs including income,during selection of cultural practices for forest and tree restoration.
文摘Children in resource poor settings are at a high risk of inadequate iron and vitamin A intake when diets lack diversity and are dominated by staple foods. Yet comparative information on diet quality among school children is scarce. The objective of the study was to assess the potential of simple food group diversity to serve as a proxy indicator of iron and vitamin A status among rural school children in Uganda. A cross sectional correlation model of associations between Food Group Diversity (FGD) and iron and vitamin A status was used. We analyzed 8 schools in Kumi District, Uganda, randomly selected from the 34 schools that participated in the main part of the study. Our sample included primary school children, aged between 9-15 years (n = 172). Food group diversity and food variety (FV) were calculated from both a food frequency questionnaire (FFQ) and a 24-hour dietary recall. The FGD and FVS were tested against iron (as serum ferritin) and vitamin A (as serum retinol) status. The FGD (based on FFQ data) was 9.6 (±1.9). There was a positive correlation between 24-hour recall and FFQ for consumption of cereals (Corr. Coef = 0.28;p 0.05), which was also the most highly consumed group (98.9% & 86.9% by FFQ and 24-hour recall;respectively). Consistent with other studies, increase in the number of food groups significantly increased serum ferritin and serum retinol measures (p 0.001). Presence of at least one food item in the “roots & tubers”;“cereals”;and “pulses/nuts”, significantly increased serum ferritin and serum retinol concentrations (p 0.01). We speculate that simple food group diversity may reflect intake and serve as a simple indicator of iron and vitamin A status among school children. Strategies aimed at increasing dietary diversity in the community may benefit the families of these children and improve their micronutrient status.
文摘Striga hermonthica(Del.)Benth is ranked as the number one constraint to maize productivity in Eastern Uganda.The use of trap crops is one of the control measures suggested for farmers with limited resources in Striga infested areas.In this study the main focus was on the effectiveness of intercropping in reducing Striga infestation and hence overall land productivity.The major objective was to identify suitable legumes in the control of Striga.In order to achieve this,on-farm experiments were conducted in Tororo and Busia districts of Eastern Uganda where the effect of the legumes on the Striga prevalence was evaluated.Maize(Zea mays)was intercropped with common beans(Phaseolus vulgaris),soybean(Glycine max)and silver leaf desmodium(Desmodium uncinatum)with sole maize(Z.mays)as the control.Soybean,beans and desmodium decreased the infestation of Striga by 26%,40%and 72%,respectively.There was a significant(p<0.05)difference in the number of emerged Striga and maize yield attained by desmodium and the rest of the legumes.Desmodium was found to be the most effective of the legumes in the control of Striga.
文摘Sorghum’s natural adaptation to a wide range of abiotic stresses provides diverse genetic reserves for potential improvement in crop stress tolerance. Growing interest in sorghum research has led to the expansion of genetic resources though establishment of the sorghum association panel (SAP), generation of mutagenized populations, and recombinant inbred line (RIL) populations</span><span style="font-family:Verdana;">,</span><span style="font-family:Verdana;"> etc. Despite rapid improvement in biotechnological tools, lack of efficient phenotyping platforms remains one of the major obstacles in utilizing these genetic resources. Scarcity of efforts in root system phenotyping hinders identification and integration of the superior root traits advantageous to stress tolerance. Here, we explored multiple approaches in root phenotyping of an ethyl methanesulfonate (EMS)-mutagenized sorghum population. Paper-based growth pouches (PGP) and hydroponics were employed to analyze root system architecture (RSA) variations induced by mutations and to test root development flexibility in response to phosphorus deficiency in early growing stages. PGP method had improved capabilities compared to hydroponics providing inexpensive, space-saving, and high-throughput phenotyping of sorghum roots. Preliminary observation revealed distinct phenotypic variations which were qualitatively and quantitatively systemized for association analysis. Phenotypes/ideotypes with root architecture variations potentially correlated with Pi acquisition were selected to evaluate their contribution to P-efficiency (PE). Sand mixed with P-loaded activated alumina substrate (SAS) provided closely to natural but still controlled single-variable conditions with regulated Pi availability. Due to higher labor and cost input we propose SAS to be used for evaluating selected sorghum candidates for PE. The ability of rapidly screening root phenotypes holds great potential for discovering genes responsible for relevant root traits and utilizing mutations to improve nutrient efficiency and crop productivity.
文摘Alfalfa (Medicago sativa L.) is an important forage and conservation crop in North America but occurrences of naturalized alfalfa in rangelands are rare. A naturalized population of yellow-flowered alfalfa in mixed-grass prairie on the Grand River National Grassland in South Dakota has potential agricultural value for the region. Despite this value, the distribution pattern of this alfalfa among and within native plant communities in the northern Great Plains is unknown. Field studies were conducted from 2003 through 2006 along topographic positions at two sites where yellow-flowered alfalfa was naturalized to evaluate the relationships of yellow-flowered alfalfa on biomass production, cover, species diversity, and alfalfa seedbank distribution characteristics. High yellow-flowered alfalfa cover (>50%) was associated with increased total biomass and occurred exclusively in swales and toeslopes that had silty loam soils. However, species diversity and non-alfalfa biomass were reduced when yellow-flowered alfalfa cover was high. Yellow-flowered alfalfa cover was lower and species richness was higher on backslopes and shoulder areas where sandy loam soils were present. A strong positive linear association existed between yellow-flowered alfalfa cover and alfalfa seedbank density (r values ranged from 0.76 to 0.82, P < 0.0001). Greater than 99% of the seeds were viable but germination rate was only 4%, indicating a high percentage of hard seed in this alfalfa population. Naturalized yellow-flowered alfalfa was a dominant component of a stable, low diversity plant community composed of mainly introduced species in rich soils of swales/toeslopes that contributed to forage production and quality in mixed-grass prairie in the northern Great Plains.
文摘Access to information and appropriate fishing gear is fundamental to the protection and conservation of the fisheries resources to guarantee sustainable livelihood of the fishers. Social networks in eight fishing settlements of Rivers State were purposively selected to assess the role of networks on access and use of information and gear among the shrimp fishers. The cross-sectional study used mixed methods to elicit data. Data obtained were subjected to content analysis and MAXQDA 2018 software to generate project maps showing information and fishing gear accessed and used. Results show that 24.8%(31) of respondents joined social network due to information sharing behavior of network members. Information was shared through one-on-one interactions, group meetings, fish buyers and phone calls. Out of the 96.8%(121) of respondents belonging to shrimp fishers’ network, 23.2% attended meetings for at least four times a month while 22.4% attended meetings for more than four times a month. Information shared bordered on price of shrimps, weather and tide, fishing grounds and traps, water level, timing of fishing and processing techniques. Respondents revealed that information shared in their networks was correct, adequate and timely. Fishing gear accessed and used proficiently was dragnet, cast net and beach seine. In all, the evidence from the interview responses suggests that networks play a key role in shrimp fishers’ access and use of information and fishing gear. Fishers are therefore, encouraged to be in one network or the other.
