Volume 6, Issue 4

Evaluating the Association between Climate Variability and Vegetation Dynamics by Using Remote Sensing Techniques: The Case of Upper Awash Basin, Ethiopia
Original Research
Examining the impact of climate variability on vegetation dynamics is the missing research element in Upper Awash Basin. Hence, the aim of this study was investigating climate variability and their impacts on vegetation dynamics. Monthly 250 meter resolution Moderate Imaging Spectro-radiometer (MODIS) Normalized difference vegetation Index (NDVI), 1kilometer resolution MODIS Land Surface Temperature (LST), rainfall data from 19 meteorological stations, and NINO3.4 (SSTA) were used for this study. A Mann Kendall (MK) trend test was used to determine the trend of each dataset using seasonal and annual time-series. Pearson correlation coefficient was also used to estimate the association between NDVI and climatic elements. Results of this study revealed that there was no significant change in the annual and seasonal NDVI, LST, Sea surface Temperature Anomaly (SSTA) and rainfall during the period 2001 to 2016, except NDVI in belg season. The correlation between NDVI and rainfall was positive (r = 0.51), strong positive (r= 0.62), low positive (r = 0.45) and low negative (r = -0.33) for annual, belg, bega and kiremit seasons, respectively. Similarly, the correlation between NDVI and LST was negative (r = - 0.58), strong negative (r= -0.67), negative (r = -0.5) and low positive (r = 0.41) for annual, belg, bega and kiremit seasons, respectively. On the other hand, the correlation between NDVI and SSTA was low negative (r = - 0.41), weak negative (r= -0.29), weak positive (r = 0.22) and low positive (r = 0.42) for annual, bega, belg as well as kiremit seasons, respectively.
World Journal of Agricultural Research. 2018, 6(4), 153-166. DOI: 10.12691/wjar-6-4-6
Pub. Date: December 28, 2018
6370 Views1558 Downloads
Efficiency of Aphid and Thrips Vectors in Transmission of Maize Lethal Necrosis Viruses
Original Research
Maize lethal necrosis disease occur in major growing regions of Kenya, causing losses of up to 100% estimated at 50 million US$ in 2014/15. The study was undertaken to evaluate the efficiency of thrips and aphids in transmission of maize lethal necrosis viruses. Maize seedlings were inoculated with adults and nymphs of Western flower thrip (Franklinella occidentalis), corn leaf aphids (Rhapolosiphum maidis) and Russian wheat aphid (Diuraphis noxia) carrying maize lethal necrosis viruses. Data collected included virus titre, disease incidence and severity and plant height. Area under disease progress curve (AUDPC) was calculated using the MLN severity data. Adults of R. maidis were the most efficient vector of Sugarcane mosaic virus (SCMV) but adults and nymphs of F. occidentalis did not transmit any of the maize lethal necrosis viruses. The highest titre of SCMV at 0.38 was noted in plants where adults of R. maidis were used to transmit viruses. Disease severity and AUDPC was highest at 44.4 % and 928.3 respectively in plants inoculated with viruses using adults of R. maidis. Inoculating maize plants with viruses using R. maidisreduced plant height by 15.1 to 18.2%. The study showed that adults of R. maidisare the most efficient in transmission of Sugarcane mosaic virus. Therefore, for effective management of maize lethal necrosis disease, management of aphid vectors is critical.
World Journal of Agricultural Research. 2018, 6(4), 144-152. DOI: 10.12691/wjar-6-4-5
Pub. Date: December 17, 2018
7841 Views1164 Downloads
Variation of Phytochemical Content and Antioxidant Capacity of Domesticated and Non-DomesticatedMomordica Charantia L. Populations in Different Maturity Stages
Original Research
Momordica charantia Linn. commonly known as bitter melon or bitter gourd is an annual plant, belongs to family Cucurbitaceae. Bitter gourd possesses antidiabetic, anticancer, anti-inflammatory, antivirus, and cholesterol lowering effects. The content and composition of bioactive molecules are varied according to the plant parts and maturity levels of the plant. However, phytochemical distribution of leaves and fruits at different maturity stages of domesticated and non-domesticated populations of M. charantia populations cultivated in Sri Lanka is scattered or lacking. Therefore, the present study was undertaken to determine the phytochemical distribution of leaves and fruits of domesticated and non-domesticated populations of M. charantia at different maturity stages. Fruits were harvested at three different maturity stages viz. 10 days (immature), 20 days (mature) and 30 days (ripen) after fruit set. Total Antioxidant Capacity (TAC), Total Phenolic Content (TPC) and Total Flavonoid Content (TFC) were determined using Ferric Reducing Antioxidant Power (FRAP) assay, modified Folin-Ciocalteu colourimetric method and the colourimetric method respectively. Results revealed that TPC and TAC were higher in immature stages and decreased with the maturity. However, values were slightly increased at ripening stage. Significantly higher TPC, TFC and TAC were reported in leaves than fruits. In conclusion, since most of the tested phytochemicals were high in immature fruits and leaves of domesticated and non-domesticated populations of Momordica charantia, immature fruits and leaves can be recommended for the production of pharmaceuticals and nutraceuticals with elevated therapeutic activity.
World Journal of Agricultural Research. 2018, 6(4), 140-143. DOI: 10.12691/wjar-6-4-4
Pub. Date: November 30, 2018
8212 Views2323 Downloads
Agricultural Exports, Economic Growth and Households Consumption in Togo
Original Research
The role of exports in stimulating economic growth continue to be the subject of many investigations. In effect, despite theoretical foundations establishing the relationship between exports and economic growth, disagreements are persistent concerning the direction of causality and the magnitude of effects. In developing countries where agriculture is a growth sector, it is worth determining the role of agricultural exports in economic growth and households’ welfare. In this paper, we have determined the relationships between agricultural exports and economic growth on the one hand and between agricultural exports and households’ consumption on the other hand in Togo. In this respect, we have performed Granger causality tests and estimate error correction models. The results indicate that there exist a unidirectional causal relationships from the agricultural exports to economic growth and households’ consumption. The results of estimation of error correction models revealed that, deviations from the long-run equilibrium in the relationship between agricultural exports and economic growth are resorbed at the rate of 44.9 percent per year whereas deviations from the long-run equilibrium in the relationship between agricultural exports and households consumption are resorbed at the rate of 28.4 percent per year. The results suggest that, policies towards agricultural exports promotion in Togo will not only stimulate economic growth but also improve households’ consumption.
World Journal of Agricultural Research. 2018, 6(4), 132-139. DOI: 10.12691/wjar-6-4-3
Pub. Date: November 23, 2018
7225 Views891 Downloads
A Study on Root Exudation Pattern and Effect of Plant Growth Promoting Fungi during Biotic and Abiotic Stress in Pigeonpea
Original Research
An experiment was conducted to observe the interaction of Fusarium udum and Macrophomina phaseolina with a rhizospheric microbe Pseudomonas [AKC-O11] to see their impact on pigeonpea under biotic and abiotic conditions. Both biotic [Fusarium udum and Macrophomina phaseolina] and abiotic stress (NaCl) were applied and performances of these microbes were evaluated. The strain was used individually and in combination with the stresses and applied as seed bacterization of pigeonpea (Var. MA-3) seeds to see the impact on total phenol content in plant root exudates. The bacterized seeds were grown under invitro conditions and after three days of germination the seedlings were exposed to biotic stress due to challenge of the pathogens [Fusarium udumand Macrophomina phaseolina] and abiotic stress due to irrigation with salt solution of 100 mM. Root exudates were collected at 48 h, 96 h and 144 h after the application of stresses. The collected root exudates were processed for total phenolic content and High Pressure/Performance Liquid Chromatography (HPLC) analysis. It was observed that total phenol content was low in seeds bacterized with Pseudomonas strain but the concentration increased when the plants were challenged with the pathogen particularly Macrophomina phaseolina and NaCl. Similarly, a similar trend was also observed in gallic acid accumulation. The above results indicates that Pseudomonas strain (AKC-O11) have potential to be used as biocontrol agent that can help pigeonpea plants to combat attack of Macrophominaphaseolina and Fusarium udumas well as salinity.
World Journal of Agricultural Research. 2018, 6(4), 122-131. DOI: 10.12691/wjar-6-4-2
Pub. Date: November 20, 2018
9750 Views1162 Downloads
Effect of Time after Incorporation of Lablab Green Manure on Root Rot Pathogens and Establishment of Common Bean (Phaseolus vulgaris L.)
Original Research
Green manure incorporation is important for restoration of soil quality, particularly buildup of organic matter and supply of nutrients to plants. However, undecomposed plant residues reduce crop establishment and plant stand. Therefore, there is need to determine suitable time for green manure incorporation before planting. The effect of time after incorporation of lablab green manure on soilborne pathogens and bean crop establishment was evaluated by incorporating 12t/ha of lablab green manure at planting and at 7, 14, and 28 days before planting. Soil samples were collected before and after incorporation of green manure at planting, and at two, four and six weeks after planting. Data was collected on crop emergence, plant stand, yield, incidence and severity of root rot, and population of root rot pathogens. Incorporation of lablab residues 28 days before planting resulted in 21% improvement in germination, with corresponding reduction in root rot incidence and severity of 8% and 36%, respectively, compared to plots incorporated with green manure at planting. Plots incorporated with lablab green manure earlier before planting had reduced population of root rot pathogens, while those incorporation at planting excited the population of root rot pathogens and also had up to 71% reduction in grain yield compared to plots where lablab residue was incorporated 28 days before planting. The results of the study showed that a period of 28 days between Lablab green manure incorporation and planting is necessary to allow for proper decomposition, resulting in a reduction in root rot incidence and an increase in grain yield.
World Journal of Agricultural Research. 2018, 6(4), 113-121. DOI: 10.12691/wjar-6-4-1
Pub. Date: November 15, 2018
8916 Views1672 Downloads1 Likes