Soil phosphorus (P) toxicity in tuber production is a significant issue and to solve this problem and have optimum tuber yield at a lesser cost of P-fertilization, knowledge in depth on the dynamics of phosphorus release in sandy loamy soil is necessary. Therefore, the present work was carried out to assess the trend of P-release from the application time to the period of its optimum release along with its effects on sweet potato growth and tuber production. For obtaining so, a 5-week incubation study under laboratory conditions was performed to study P-release dynamics using different P sources. Another similar field experiment was concurrently conducted using the same P sources and application rates to monitor the influence of P-release rate on sweet potato production. Various parameters, namely leaves, vine length, tuber yield, soil extractable phosphorus and leaf phosphorus uptake were taken into consideration. Relationships were also established between P-uptake and tuber yield, number of leaves and vine length. The curve of the trend of the phosphorus release was S-shaped. Also, P-application improved the production of leaf and vine length while tuber yield was suppressed. The study recommended that P-fertilizer should not be applied at close intervals even if its effects are yet to be felt on plants.
Aims: This study is based on the use of the FAO AquaCrop model to determine the amount of water needed to improve corn yields in Northern Cameroon.
Study Design: The regions of Garoua (9˚18'N - 13˚24' E), Kaélé (10˚05'44"N - 14˚26'37"E) and Maroua (10˚35'N - 14˚19’E) were considered for this purpose. This region corresponds to a semi-arid zone in the Northern Cameroon in Central Africa.
Place and Duration of Study: The climate data used in this work were collected in the meteorological stations of Garoua, Maroua and Kaélé from 1979 to 2004 during the AMMA (African Monsoon Multidisciplinary Analysis) project. The phenology data of maize crops were obtained from the Institute of Agricultural Research for Development (IARD) which is the national institute.
Methodology: The software used here is AquaCrop, developed by a group of experts at the Food and Agriculture Organization (FAO) for prediction of agricultural production under conditions of water limitation. Two simulations were carried out to determine the impact of climate change on agricultural yields and to determine the amount of water needed to mitigate this impact. The first consists of estimating yields in the dry and rainy seasons. The second consists of the estimation of the yields that are in the dry season or in the rainy season by using the irrigation. Hence, we have estimated the quantities of water needed for irrigation for each season over the region.
Results: The yields of the maize crop are most important during the rainy season and are close to 2.32 ton/ha. If irrigation is done during this season a rate of 72.15 mm, these yields are improved to 2.56 ton/ha. In the dry season, yields are close to 0.15 ton/ha. When irrigation is done with an average rate of 427.03 mm, yields are considerably improved and are relatively close to those obtained in the rainy season (2.37 ton/ha).
Conclusion: This study allows farmers to cultivate in all seasons to preserve and improve food security in the future years.
Aims: The aim of this study was to determine the status of restricted-range bird species of East African coastal biome, particularly within the Southern coastal forests of Kenya and as a proxy of the conservation value of the current existing fragmented forests.
Study Design: Ecological survey design, using point counts method.
Place and Duration of Study: The study was carried out in south-coast forests of Kenya within Kwale County between July 2007 and February, 2008.
Methodology: Five forests out of more than 10 forest fragments differing in sizes were randomly selected in the coastal area between the coastline and about 60 km inland within Kwale County, Kenya. Point counts were systematically placed at each forest, spaced at least 200 m from each other hence three forests namely Marenje, Nzombo and Mrima had 50 point counts each owing to their large size, while Diani and Kaya Waa had 15 and 7 point counts respectively.
Results: The findings showed that nearly half (48%) of the restricted-range bird species of East African Coastal Biome are found in the south coast forests of Kenya, 78% of which are truly forest birds. Some specific forest species such as Anthus sokokensis has been lost here while the occupancy range of Anthreptesreichenowi seems to have shrank from earlier records. Though all forests are found to be important, larger forests are particularly critical for the conservation of these birds. This means forests are the only refuge remaining for the restricted-range bird species in coastal Kenya.
Conclusion: The south coast forest fragments should be conserved irrespective of size, but the management should mainly aim at maintaining larger forests as the only way of ensuring persistent occupancy of East African Coastal biome restricted-range species.
This study was conducted in wanzaye natural forest, South Gondar, Ethiopia. The main objective of the study was to determine the species composition, diversity and vegetation structure analysis of wanzaye natural forest. A total of 75 quadrants or plots were used. Each sample plot covered an area of 400 m2 (20m x 20 m). For trees/ shrubs, all woody species with diameter at breast height (DBH) >2.5 cm and height >2 m were recorded in all plots. For the regeneration purpose, trees/shrubs species with diameter < 2.5 cm and height < 2 m also recorded. Diversity and richness were calculated using the Shannon- Wiener diversity index. All Woody species population was examined by estimating Frequency, relative Frequency, density, relative density and Dominance (basal area). Basal area was calculated using the cross-sectional area of a tree trunk measured at diameter at breast height (DBH, 1.3 m height) Excel and STATISTICA version 10 software were used to analyse vegetation data. The result indicated that a total of 49 woody species belongs to 29 families were identified. The total basal area was 23.3 m2 ha-1. Number of individuals with (DBH) >2.5cm and height >2 m was 482 trees ha-1 and for the regeneration it was (2916 individuals ha-1). Based on Importance Value Index (IVI) Ficus sycomorus (56%) followed by Dodonaea viscosa (31%) and Croton macrostachys (19%) was recorded. The overall diameter frequency distribution of woody species show inverse J- shape.
The vegetative and reproductive phenology of 17 overstorey and 10 understorey species were studied in the Takamanda National Park in Cameroon. Phenological observations; leaf initial, maturation, abscission, flush (vegetative), while flower initiation, maturation, dropping and fruit initiation, maturation, dropping and ripening (reproductive) were carried out monthly for two years (January 2012 - December 2013). Results indicated that phenological behaviour of most of the tree species was similar for the two years of monitoring. A prominent peak in leaf abscission, leaf initiation, flower initiation and fruit ripening of overstorey species occurred in December, February, July-August and February-March respectively. However, the peak periods of such phenological events in understorey species were different from that of the overstorey species. It was noted that fruit maturation and ripening of the overstorey species attained their major peak in December and a minor peak in February while the understorey tree species recorded their main peak in March and minor in February. Leaf flushing for both overstorey and understorey species occurred at the end of the dry season (January- February). Fruit dropping in many species coincided with early rains, thus ensuring available moisture for seed germination and establishment. Temperature was (P<0.01) significantly positively correlated with fruit ripening for the overstorey and understorey species. Rainfall was significant (P<0.01) but was negatively correlated with leaf initiation, leaf dropping, flower initiation and fruit ripening. The phenological information obtained in this study is mostly influenced by the seasons and would be useful for planning proper management strategies to sustain plant regeneration dynamics in the Takamanda National Park.