Characterizing Vulnerability of Crop-Based Rural Systems to Climate Change and Variability: Agro-Ecology Specific Empirical Evidence from the Dabus Watershed, North-West Ethiopia

Climate change is impacting climate sensitive rural livelihood systems. Exposure, sensitivity, and adaptive capacity of agricultural livelihoods to climate variability and change differ across agro-ecologies and these pose a challenge to climate resilient development strategy. This study assesses agro-ecology specific vulnerability of smallholder farmers to climate change and variability in the Dabus Watershed (North-west Ethiopia), based on a survey of 734 farm households complemented with focus group discussion and key informant interviews. Recognizing the physiographic and climatic diversity that exists across agro-ecologies in the study area, Livelihood Vulnerability Index (LVI) framed within the United Nations Intergovernmental Panel on Climate Change (IPCC) vulnerability framework (LVI-IPCC) is adapted to assess agro-ecology specific vulnerability in two local agro-ecologies, namely wet lowland and dry lowland. For each agro-ecology, exposure, sensitivity and adaptive capacity indices as well as LVI-IPCC vulnerability score was calculated. The result shows that the dry lowland agro-ecology has a relatively higher exposure and sensitivity to climate stresses with a comparatively limited adaptive capability. On the other hand, the wet lowland agro-ecology exhibits intermediate vulnerability with a relatively lower perceived exposure and higher adaptive capacity. Higher exposure relative to adaptive capacity resulted in a positive LVI-IPCC score in the dry lowland agro-ecology and positioned it in more vulnerable level than the wet lowland. A higher adaptive capacity relative to exposure unveils a negative LVI-IPCC score for the wet lowland agro-ecology and positioned it in a moderate vulnerability category. In line with the findings, there is a need to set agro-ecology specific priorities for intervention that is most needed to cop up with the effects of climate variability and change in each agro-ecology. Climate risk exposure levels can be reduced through timely provision of climate specific information and early warning systems aimed at enhancing preparedness of farm households to extreme events. It is also crucial to expand availability of infrastructural facilities such as market, health services, and veterinary services so as to enhance adaptive capacity. Supporting alternative livelihood options and enhancing water harvesting practices for supplementary irrigation also call policy attention.

Sustainability issues in agro-ecology: Socio-ecological perspective

In the recent past there has been concern to address the declining trends and deteriorating ecological elements and their functions in productive agricultural landscapes. The efforts to revive the ecological functions needs multiple scale approach, which include scientific understanding, time dependent restorative activities and incorporation of wisdom of the stakeholders. Conservation initiatives linked to precision farming is an apt mechanism to minimize the loss of natural resources of agricultural landscapes to maintain the complex stabilizers of ecological functions. Such an effort must address the scientific evaluation of the farm as “ecologically sustainable unit” with due consideration to social construct at local to regional level. Sustainability indices can be useful tools for evaluating the farms to isolate degradative factors and identify ecologically conservative practices. This review will analyze certain inter-linked concepts relevant to address the sustainability issues in agro-ecology at the interface of socio-ecological perspective.

Preservation Potentials of Essential Oils of Ocimum basilicum and Ocimum gratissimum from Two Agro-Ecological Zones on Freshwater Smoke-Dried Oreochromis niloticus Fish Sold in Some Local Markets in Cameroon

Dried fish are susceptible to bacteria and fungi attack and are liable to chemical changes which cause losses in quality and reduction of shelf-life. It is important therefore to maintain the quality of fish because continuous consumption of contaminated fish and their products may predispose consumers to health hazards. Maintenance of high quality fish therefore calls for adequate and effective preservation techniques. The study examined the effectiveness of essential oils of Ocimum basilicum and Ocimum gratissimum from two Agro-ecological zones of Cameroon in limiting the microbial proliferation and preserving the quality of smoke-dried Oreochromis niloticus fish stored at 25˚C for two months. The plant materials were harvested from the Western Highlands and Monomodal Humid Forest agroecological zones of Cameroon. Extraction of the essential oil from the plants was done by hydro-distillation. The fish species (Oreochromis niloticus) used in this study was chosen based on a survey study on the most consumed species of freshwater smoke-dried fish in the Western Highlands and Monomodal Humid Forest Agro-ecological zones of Cameroon. Heterotrophic bacteria counts, fungi counts and Enterobacteriaceae counts were used to assess the level heterotrophic bacteria, fungi and Enterobacteriaceae respectively in the fish samples during storage and were done by culture techniques using total plate count agar, potato dextrose agar and violet red bile glucose agar respectively. Total volatile basic nitrogen, peroxide value, and thiobarbituric acid reactive substance assays were used as spoilage indices to assess the nutritional quality of the fish during storage. From the survey study, Oreochromis niloticus was the most consumed smoke-dried fish in the Western Highlands (35.45%) and Monomodal Humid Forest (34.55%) agroecological zones. All the EOs caused a significant reduction in the microbial loads, total volatile basic nitrogen, peroxide value, and thiobarbituric acid reactive substance of smoke-dried Oreochromis niloticus as storage progressed. However, the reduction in these values was more pronounced in samples treated with essential oils of O. gratissimum from the Western Highlands, with heterotrophic bacteria, fungi and Enterobacteriaceae counts being 5.89, 6.97 and 4.59 log10 cfu/g respectively at the end of the storage period. This was followed by essential oils of O. gratissimum from the Monomodal Humid Forest with heterotrophic bacteria, fungi and Enterobacteriaceae counts being 6.11, 7.79 and 4.86 log10 cfu/g respectively at the end of the storage period. Also, essential oils of O. gratissimum from the Western Highlands was more effective in preserving the fish quality as lowest total volatile basic nitrogen (12.29 mg/100g), peroxide value (2.79 mEq O2·Kg−1) and thiobabituric reactive substance (1.695 mg MDA/Kg) values were observed for fish samples treated with this extract at the end of the storage period. This was followed by essential oils of O. gratissimum from the Monomodal Humid Forest with total volatile basic nitrogen (14.95 mgN/100g), Peroxide value (3.23 mEq O2·Kg−1) and thiobabituric reactive substance (2.354 mg MDA/Kg) at the end of the storage period. From the results obtained, essential oils from O. gratissimum were more effective than that from O. basilicum in the two agroecological zones and should be considered as natural alternative to chemical preservatives for further application in food preservation.

Efficiency of soil and water conservation practices in different agro-ecological environments in the Upper Blue Nile Basin of Ethiopia

In developing countries such as Ethiopia, research to develop and promote soil and water conservation practices rarely addressed regional diversity. Using a water-balance approach in this study, we used runoff plots from three sites, each representing a different agro-ecological environment, e.g., high, mid and low in both elevation and rainfall, in the Upper Blue Nile Basin of Ethiopia to examine the runoff response and runoff conservation efficiency of a range of different soil and water conservation measures and their impacts on soil moisture. The plots at each site represented common land use types（cultivated vs. non-agricultural land use types） and slopes（gentle and steep）. Seasonal runoff from control plots in the highlands ranged 214–560 versus 253–475 mm at midlands and 119–200 mm at lowlands. The three soil and water conservation techniques applied in cultivated land increased runoff conservation efficiency by 32% to 51%, depending on the site. At the moist subtropical site in a highland region, soil and water conservation increased soil moisture enough to potentially cause waterlogging, which was absent at the lowrainfall sites. Soil bunds combined with Vetiveria zizanioides grass in cultivated land and short trenches in grassland conserved the most runoff（51% and 55%, respectively）. Runoff responses showed high spatial variation within and between land use types, causing high variation in soil and water conservation efficiency. Our results highlight the need to understand the role of the agro-ecological environment in the success of soil and water conservation measures to control runoff and hydrological dynamics. This understanding will support policy development to promote the adoption of suitable techniques that can be tested at other locations with similar soil, climatic, and topographic conditions.

Evaluation of the Efficacy of an Aloe barbadensis Based Biological Insecticide against Pests of Abelmochus esculentus for Promoting Ecological Agriculture (Far-North, Cameroon)

Chemical insecticides have been considered as a means to combat crop pests. Although their effectiveness is evident, their impact on the environment is increasingly being discussed. The aim of this study is to determine the agro-ecological potential of a biological insecticide (C25H32O12) based on Aloe barbadensis in a Sahelian context. For this purpose, a completely randomized block experimental design with 3 replications and 4 treatments was set up to experiment with Aloe barbadensis as a bioinsecticide against pests of Abelmoschus esculentus. However, data were collected using an observation and parameter monitoring grid. This includes the cultivation of Abelmoschus esculentus, soil preparation, seeding and watering, plot labeling, preparation of the bioinsecticide (selection and preparation of raw materials, grinding of Aloe barbadensis miller and extraction of the crude bioinsecticide, quantification of treatment doses and dilution, and obtaining the formulated bioinsecticide), plant watering, plant treatment, and finally parameter monitoring. The results obtained reveal that the level of damage is significantly high in the control treatment T0 (63%) compared to the other treatments, with 29% for treatment T1, 7% for T2, and 1% for T3, implying a strong action capability of this insecticide against pests of Abelmoschus esculentus. Therefore, it can be concluded that for a normal growing season of Abelmoschus esculentus, this biological insecticide should be sprayed 12 times. Furthermore, this biological insecticide is unique in that it does not inflict any gastric toxicity on the pests, which gives it the characteristic of being a repellent. It is a biological insecticide whose efficacy period has been tested, with a minimum duration of 21 days. In conclusion, this formulated bioinsecticide based on Aloe barbadensis demonstrates significant efficacy against pests of Abelmoschus esculentus. In the future, we will consider experimenting with its effectiveness against pests of other plants.

Agro-Ecological Assessment of Non-Traditional Export Crops in North East Trinidad

North-East Trinidad is a low income, underutilized, agro-ecological significant and agricultural community with great potential for producing non-traditional crops for domestic usage and export. Diversification is critical to agro-ecological transitions to ensure food security and nutrition while conserving, protecting and enhancing natural resources. The growing demand for agro-ecological and food security solutions suggest that efforts be made to utilize sustainable agriculture, and agro-ecological methods by utilizing available rural landscapes and communities in an effort to fulfill these demands. Surveys of sustainable agriculture, organic farmers and agro-ecological interests were conducted in the impoverished region of North-East Trinidad. Survey results reported over 180 farmers with >1 - 10 acres of available farmland supported a high agricultural production capacity. The highest average per capita for vegetables was tomato (2.3 acres), for tubers was yam (1.03 acres), and for tree crops was green fig (900 plants). Livestock production was limited with duck production being highest (165). There is an increasing earning potential for small farmers and leaseholders, from utilization of non-traditional export crops and expanding agro-ecological land usage, increasing sustainable agriculture production in the area.

Agro-ecological engineering in China: a way towards sustainable agriculture

Sustainable development, as a “hot topic”, concerns not only economic development but also environmental protection. Agriculture, the base of other economic activities, has faced many difficulties that include over growth population, land decrease, and land degradation and so on. Therefore, how to increase the food supply, to meet the over\|growth population demands, is the main task all over the world at present, especially in the developing countries, such as China, but we also must protect agricultural environment for medium\| and long\|term development simultaneously. Hence, sustainable development in agriculture is the most important estate that we must concern. Its sustainable development determines the sustainability of other economic development to a great extent. Despite Chinese government has paid much attention to develop agricultural production and obtained great successions, there are also many shortcomings in Chinese agriculture. Therefore, China must seek new approaches for its development and environmental protection that suit local conditions and are based on local resources. Agro ecological engineering, the application of ecological engineering in agriculture, is very thriving in China in recent decades. In this paper, the ecological, economic and social benefits of agro\|ecological engineering are analyzed. The principles are discussed. The results indicated that agro\|ecological engineering can meet the farmer′s short\|, medium\| and long\|term benefits. In the meanwhile, it also concerns not only economic benefits but ecological and social benefits. Therefore, agro\|ecological engineering is a way that leads to sustainable agriculture in the future in China.

The Dynamic Analysis of Agro-ecological Economic System on the Basis of Emergy: A Case Study of Wu'an City in Hebei Province

Using the method of emergy analysis, we analyze the input and output of agroecological economic system, and select five indicators (net emergy yield ratio, emergy investment ratio, environmental loading ratio, emergy sustainability index, and dominance of emergy yield system) for assessment. The results show that the emergy input-output in Wu'an City is in general on the rise; the emergy investment ratio rises constantly, but the net emergy yield ratio decreases, and the comparative advantage in the prices of agricultural products is gradually lost. At the same time, with increase in the non-renewable industrial support emergy, the environmental pressures are also mounting. In the future agricultural development, it is necessary to pay more attention to the coordination between agricultural development and ecological environment, achieving sustainable development of agriculture.

Discussions and Recommendations about Establishing Agro-ecological Compensation Mechanism in Jiangsu Province

Establishing agro-ecological compensation mechanism is the objective requirement for protecting agricultural ecological environment on the prerequisite of stabilizing and benefiting farmers,to realize protection in the process of development and promote development through protection.This study analyzed existing problems in the practice of establishing agro-ecological compensation mechanism in Jiangsu Province,including failure to form systematic compensation system due to limited technological reserve,failure to bring into play expected compensation effect due to scant attention,and failure to set up perfect input mechanism due to insufficient financing channel.In line with these problems,it came up with feasible policy recommendations,including strictly implementing top frame design for agro-ecological compensation and giving impetus to standardized and institutionalized work,building pilot demonstration area for agro-ecological compensation,setting up diversified agro-ecological compensation approaches,establishing long-term security mechanism for agro-ecological compensation,and strengthening propaganda and education of agro-ecological compensation.It is expected to provide reference for establishing agro-ecological compensation mechanism in Jiangsu Province,and also provide system guarantee for promoting ecological progress and agricultural modernization in Jiangsu Province.

The Spatio-Temporal Variability of Rainfall over the Agro-Ecological Zones of Ghana

Rainfall variability plays an important role in many socio-economic activities such as food security, livelihood and farming in Ghana. Rainfall impact studies are thus very crucial for proper management of these key sectors of the country. This paper examines the seasonal and annual rainfall variability in the four agro-ecological zones of Ghana from the CHIRPS V2 rainfall time series spanning a period of 1981-2015. The rainfall indices were computed with the aid of the FClimDex package whereas the trends of these indices were further tested using the Mann Kendall trend test. The results show good agreement (r ≥ 0.7) between CHIRPS V2 and gauge in almost all portions of country although high biases were observed especially in DJF season over parts of the Northeastern (NE) portions of the country. The mean seasonal rainfall climatology over the country is observed to be in the range of 20 - 80 mm, 60 - 200 mm, 100 - 220 mm and 40 - 180 mm in DJF, MAM, JJA and SON seasons respectively with high intensities of rainfall dominating Southwestern portions of the country. The trend analysis revealed positive trends of consecutive dry days in the Transition, Forest and Coastal zones and negative trends in the Savannah zone of the country. Decreasing trends of consecutive wet days are observed over the Savannah, Transition and Coastal zones whereas increasing trends dominate the Forest zone. Savannah, Forest and Transition zones show weak increasing trends of the number of heavy rainfall days whilst weak decreasing trends are observed over the Coastal zone of the country. Similarly, weak increasing trends of the number of very heavy rainfall days are observed over all the agro-ecological zones except in the Transition zone. It is observed that the annual wet day rainfall total has increasing trend in the Savannah and Forest zones of the country whereas decreasing trends cover the remainder of the zones. The trends of these indices in the agro-ecological zones were all significant at a significant value of 0.05. This paper assessed the performance of the CHIRPS V2 rainfall data over the region and reports on the biases in seasonal rainfall amounts which are limited in previous studies. These findings have adverse impacts on rain-fed agricultural practices, water resource management and food security over the country.

Post-Harvest Fungi Associated with Cowpea (Vigna unguiculata L. Walp.) Seeds Produced in Burkina Faso

Cowpea is a very popular foodstuff among people in sub-Saharan Africa. In Burkina Faso, it is the main food legume, especially in rural areas. Its production is facing difficulties including post-harvest losses caused by fungi. Therefore, the objective of this study was to isolate and identify fungal strains associated with cowpea seeds produced in Burkina Faso. Thus, a total of 108 seed samples were collected in the three agro-ecological zones of Burkina Faso. The sanitary analysis of the seeds was carried out using the direct contact method. The isolation and purification of the isolates were performed on Potato Dextrose Agar medium while their identification was done through macroscopic and microscopic phenotypical characterization using different culture media (Potato Dextrose Agar (PDA), Malt Extract Agar (MEA) and Czapeck Dox Agar (CZA)) and different identification keys. A total of 10 fungal species were isolated, with predominance of Aspergillus flavus, Aspegillus niger, Macrophomina phaseolina, Fusarium oxysporium and Rhizopus sp. whose infection rates were 70.8% to 100% of seed samples. In addition to being present in all three zones, the infection rates of Aspergillus flavus (56.55%), Aspergillus niger (20.35%) and Rhizopus (32.80%) were higher in the Sahelian zone. In the Sudano-Sahelian zone, Macrophomina (50.66%) and Fusarium (18.88%) presented the highest infection rates, while Penicillium sp. showed the highest infection rate (2.84%) in the Sudanian zone. This finding demonstrated the necessity to improve post-harvest and conservation techniques of cowpea to limit crop losses and preserve the sanitary quality of this important foodstuff.

A Review of the History and Development of Integrated Pest Management(IPM)

The evolvement of IPM has experienced several significant stages. IPM is an ecosystem as a governance unit. It allows the presence of low numbers of pests because a direct or indirect relationship between biological species and their associated environmental living conditions could keep a long-term ecological balance. IPM also emphasizes overall benefits; it is necessary to integrate all kinds of safe, effective, economic, and simple managements as far as possible. When synthesizing and coordinating various managements, effective control object, effective time limit, effective scope, and effective degree of the individual method should be analysed first. The ultimate goal of IPM is for the sustainable development of agriculture. In the future IPM system engineering, crop resistance, the role of natural enemies, agricultural control, and the application of biological control technologies will be greatly strengthened, and the role of chemical pesticides will be significantly reduced. Safe, effective, and long-lasting control of pest populations will be below the level of harm caused, which could protect the ecological environment and the health of people and livestock, and promote the development of production.

Screening Azadirachta indica tree for enhancing azadirachtin and oil contents in dry areas of Gujarat,India

Azadirachta indica seed samples were collected from four different agro-ecological regions（AERs） viz.,AER-2,AER-4,AER-5A and AER-5B of Gujarat state,India during 2000 to 2002 with an aim to assess variability in azadirachtin,oil and fatty acids content of the seeds and assess correlation of these parameters with morphological characters.Azadirachtin,oil and fatty acids content indicated significant（p0.01） variations between years and AERs in Gujarat.The azadirachtin ranged from 142 to 9 527 μg·g-1 seed kernel with an average of 2 426 μg·g-1 for the state.AER-5B recorded highest azadirachtin and oil content.Fatty acid composition was found to be affected by environmental factors particularly varying degree of annual rainfall and temperature during fruit ripening period.Conclusively trees growing in AER-5B performed better in term of azadirachtin,oil and stearic acid content.Tree girth at breast height showed no significant relation with these biochemicals.

Variation of Physiochemical Components of Acid Lime (<i>Citrus aurantifolia</i>Swingle) Fruits at Different Sides of the Tree in Nepal

Acid Lime (Citrus aurantifolia Swingle) is one of the important commercial fruits cultivated from terai to high hill of Nepal. It is an important source of vitamin “C” (ascorbic acid) for human nutrition. Amount of juice, TSS (Total soluble solids), TA (Titrable acid) and vitamin C are the determining factors of quality of acid lime fruits which may vary according to bearing sides of the trees. The main objective of this study is, to determine the variation of fruit quality at different sides of the tree. Total of 15 bearing trees were selected randomly (5 trees per site) from three different agro ecological domain representing terai (1200 m asl) and samples were collected from the selected trees. Randomly ten fruits (from east, west, centre, north and south sides) were collected from each tree and analyzed for amount of vitamin C, TSS, TA and juice. Highest ascorbic acid 79.6 mg and 69.9 mg was observed in south side fruits whereas lowest 62.8 mg and 55.1 mg was observed in centre fruits in the high and mid hills zone respectively, but in terai, highest ascorbic acid 58.7 mg was observed in north side and lowest 41.8 mg was observed in centre. Highest amount of juice 43.9% was observed in south side fruits and lowest 36.6% in centre fruits, but amount of TSS 8.2% and TA 7.2% was observed in south side fruits and lowest 7.3% TSS and 7.0% TA was observed in centre fruits in high hills. In terai highest TSS 8.3% and TA 7.4% was observed in north side fruits and lowest TSS 7.3% and TA 6.7% was observed in centre fruits. Variation of TSS, TA percent and ascorbic acids was observed according to the agro ecological zone.

Emergy Analysis of Agro-ecosystem in Poyang Lake Area

By using emergy analysis theory and methods, we conduct quantitative analysis on the input and output of emergy, and sustainable development of agro-ecological system in Poyang Lake Area. The results show that compared with the national average, the environmental loading ratio is relatively low in this area; the net emergy yield rate is high; the sustainable development ability is strong. Finally according to the results of emergy analysis, corresponding countermeasures are put forward as follows: develop agriculture based on the existing rich natural resources; increase technological inputs; develop circular agriculture; promote sustainable agricultural development.

Mitochondrial D-loop diversity of grasscutter (<i>Thryonomys swinderianus</i>Rodentia: Hystricomorpha) in Ghana

Attempts are being made to domesticate the grasscutter (Thryonomys swinderianus) for commercial production in Sub-Saharan Africa to cater for the protein needs of the people and to satisfy the craving for bushmeat, thereby reducing habitat destruction through hunting. The objective of this study was to determine the genetic diversity of grasscutter populations in Ghana. DNA was extracted from roots of hair samples collected from 84 grasscutters from three agro-ecological zones in Ghana, namely Guinea Savanna (n = 17), Forest (n = 22), and Coastal Savanna (n = 45). Mitochondrial D-loop was sequenced and the diversity was determined across the zones. Out of 26 haplotypes found, 15 were obtained from Guinea Savanna, 7 from Forest and 13 from Coastal Savanna. Haplotype diversities were 0.978, 0.853 and 0.875 respectively for Guinea Savanna, Forest and Coastal Savanna zones. Analysis of molecular variance (AMOVA) revealed significant differentiation between Forest and Savanna populations (FST = 0.14, p 0.05). Network analysis indicated two clusters, one of which consisted of only Savanna haplotypes. Population neutrality tests showed that Forest and Coastal Savanna populations had been stable while the Guinea Savanna zone population had undergone an expansion (Fu’s FS = ‐7.132,

Heavy Metals Uptake in Maize Grains and Leaves in Different Agro Ecological Zones in Uasin Gishu County

Maize grain is the second most vital food after wheat to humans and forms an important part of a human diet due to its nutrients. In Kenya, it is estimated that one out of every two acres of land put to crop production is under maize crop. Maize can also be fed whole to livestock (grazed or chopped and ensiled). Due to increased demand and the need for higher productivity, farmers have adopted modern farming methods which include use of fertilizers, pesticides, compost manure, and irrigation. Uses of these products elevate amounts of heavy metals in the soil. Such heavy metals such as lead (Pb) and cadmium when taken up by plants accumulate in the plants becoming toxic at high levels. It is essential to monitor these levels in grains and leaves to ensure they do not exceed the WHO permissible limits. This study aimed at monitoring the levels of heavy metals uptake in maize (Zea mays) grains and leaves is within permissible levels. Level of heavy metals in maize grains from different ecological zones in UG County had mean concentration of Zn 0.122, Cd 0.03, Cu 0.111, Co 0.04, and Pb 0.33 mg/kg. These results were below WHO standards except for Cadmium, Co, and Pb which were slightly higher than recommended standard. The study also found that maize leaves had mean concentration of Zn 0.115, Cd 0.04, Cu 0.117, Co. 0.041 and Pb 0.323 mg/kg. The results were below WHO standards except Co and Pb which had slightly higher levels than the recommended WHO standards. The analytical results from this study provided important baseline statistics on the concentration of selected heavy metals in maize grains and leaves besides being an important assessment of environmental pollution in rural areas where maize farming is predominant.

Assessment of Soil Erosion and Climate Variability on Kerio Valley Basin, Kenya

This study was aimed at assessing soil erosion, climate variation and how climate has affected both the agro climatic and agro-ological zones of Kerio Valley basin. The basin faces challenges especially soil loss, due to the massive degradation that takes place in Kerio valley. Due to the increase in rainfall recently experienced in the area, most of the top soil has been carried away leading to excessive degradation of the valley, causing soil loss in the basin and subsequent deposition of the sediments in Lake Kamnarok which is an oxbow lake posing it to the threat of extinction. All these aforementioned factors, i.e. soil erosion, climate variation and land degradation have contributed to reduction of water storage capacity of the Lake. The main objective of this study was to assess the effects of soil erosion, climate variation on the basin and climate effect on agro-climatic and agro-ecological zones of the basin. Agro-climatic zones show how climate variability shapes agricultural landscape of an area while agro-ological zones show how agriculture affects the ecology of the basin. This includes the reduction of the lake size that has led to the disruption of the ecology of Lake Kamnarok and its environs, the major implications being the lake size reduction as the lake is proved to be a home for reptiles especially crocodiles. All these factors were finally assessed to determine their effect on water reduction capacity of Lake Kamnarok. The results depicted that the major factors that have caused changes in the basin and the Lake include heavy rainfall that has resulted in soil erosion and subsequent land degradation. These factors have eventually affected the agroclimatic and agroecological zones of the basin. This study integrated the use of Geographic Information System (GIS) and Remote Sensing (RS) to assess the areas with massive degradation and to quantify the amount of soil loss using Revised Universal Soil Loss Equation (RUSLE) model. It was concluded that the main factor that caused the changes in the agroclimatic and the agroecological zones was soil erosion which was influenced by climatic factors, i.e. rainfall and temperature.

ISSR-Based Molecular Characterization of an Elite Germplasm Collection of Sweet Potato(Ipomoea batatas L.) in China

To determine the genetic diversity and population structure of sweet potato accessions cultivated in China, and to establish the genetic relationships among their germplasm types, a representative collection of 240 accessions was analyzed using inter-simple sequence repeat （ISSR） markers. The mean genetic similarity coefifcient, Nei’s gene diversity, and shared allele distance of tested sweet potato accessions were 0.7302, 0.3167 and 0.2698, respectively. The 240 accessions could be divided into six subgroups and ifve subpopulations based on neighbor-joining （NJ） clustering and STRUCTURE results, and obvious genetic relationships among the tested sweet potato accessions were identiifed. The marker-based NJ clustering and population structure showed no distinct assignment pattern corresponding to lfesh color or geographical ecotype of the tested sweet potato germplasm. Analysis of molecular variance （AMOVA） revealed small but signiifcant difference between white and orange-lfeshed sweet potato accessions. Small but signiifcant difference were also observed among sweet potato accessions from the Southern summer-autumn sweet potato region, the Yellow River Basin spring and summer sweet potato region and the Yangtze River Basin summer sweet potato region. This study demonstrates that genetic diversity in the tested sweet potato germplasm collection in China is lower than that in some reported sweet potato germplasm collections from other regions. Pedigree investigations suggest that more diverse Chinese sweet potato varieties should be formed by broadening the selection scope of breeding parents and incorporating the introduced varieties into future breeding programs.

In vitro biological activities of aqueous extracts of Tetrapleura tetraptera(Schumach. & Thonn.) taub. and Aframomum citratum(C. Pereira) K.Schum from three Agroecologic Zones in Cameroon

Objective:To investigate some phytochemical constituents and biological activities of twelve samples of Tetrapleura tetraptera(Schumach&Thonn.)taub.and nine samples of Aframomum citratum(C.Pereira)K.Schum fruits collected in the bimodal forest zone(ZONEⅤ),the unimodal forest zone(ZONEⅣ)and the highlands zone(ZONEⅢ)in Cameroon.Methods:Fresh fruits extracts were obtained by aqueous infusion(100℃during 15 min)and evaluated by spectrophotometric methods for total polyphenol(TPP),total flavonoids(TFLV)contents and antioxidant(DPPH,total antioxidant capacity by the phosphomolybdenum method,iron reducing power or ferric reducing antioxidant power and inhibition of beta carotene discoloration assays)and anti-inflammatory(inhibitions of protein denaturation and 5-LOX represented by INH.PROT and INH.5-LOX respectively)properties.Principal component analysis was performed.Results:For both species,fruits from ZONEⅤhave the highest TPP,TFLV levels and biological activities.TPP and TFLV content of Aframomum citratum and Tetrapleura tetraptera fruits are positively and significantly(P<0.05)correlated.The biological activities of all extracts(0.25,2.5,25,250 mg/mL)were dosedependent and the extracts have shown strong antioxidant and antiinflammatory activities,but less than references(ascorbic acid,diclofenac,quercetin,and butylated hydroxytoluene).There was a positive correlation between TPP,TFLV and total antioxidant capacity,ferric reducing antioxidant power,and inhibition of beta carotene discoloration assays,and inverse correlations were observed with the IC50(g/mL)of DPPH,INH.5-LOX and INH.PROT assays for both species.Conclusions:The fruits exhibit variabilities and those from ZONEⅤfor both species are economically and healthcare challenging for herbalists,pharmaceutical firms,scientists and consumers.Indeed,most important extraction yield of bioactive compounds correlated with significant biological activities and the use of less material compared with an implementation in other Agro-ecologic Zones with the same results are noted.