Browsing by Author "Iddrisu, A."
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Item Anatomical, Germination And In Vitro Studies On Shea Tree (Vitellaria Paradoxa C.F.Gaertn.) Seed(University of Ghana, 2013-07) Iddrisu, A.In vivo and in vitro germination and regeneration studies were conducted on the development of Vitellaria paradoxa seedlings as an initial effort towards its domestication. However, to achieve this objective, the morphology and anatomy of the seeds were first studied because they influence germination. Although a smooth, brown coat encloses a V. paradoxa seed, it did not impose dormancy on the embryo. Transverse and longitudinal sections through the seed showed that the embryo is surrounded by latex- and fat-containing tissues which made its identification difficult. Thus, the embryo was identified by immersing transversely cut seeds in 1.0 % tetrazolium chloride (TTC) solution for 24 hours which stained it red. When V. paradoxa seeds of similar size were sown on nursery beds, the resulting seedlings developed through seven stages namely sprouting, pseudoradicle elongation, bulging, appearance of the shoot on the pseudoradicle, shoot elongation, emergence and seedling establishment. The pseudoradicle is the fused petioles of the two cotyledons and a transverse section through it revealed an outer sheath and lactiferous vessels surrounding a central hollow tube. Longitudinal section also showed the lactiferous vessels surrounding the central hollow tube in which the plumule moves through until it reaches the bulge of the pseudoradicle where it develops into a rudimentary shoot. The rudimentary shoot then protrudes from the pseudoradicle and grows upwards. Classifying seeds into three groups based on sizes and sowing them on nursery beds showed that seed size significantly affected days to germination and the morphology of the resulting seedlings. Large seeds germinated within one week after sowing with vigorous growth compared to small and medium seeds. Although the seedcoat of V. paradoxa never imposed dormancy, deshelling (removal of the seedcoat) significantly led to early germination and synchronous seedling emergence compared to those for intact seeds (control). In vitro culture of intact and deshelled seeds on Murashige and Skoog (1962) basal salts modified with 6-benzylaminopurine (BAP) produced no plantlets although 80 % of the deshelled seeds developed long pseudoradicles on a medium supplemented with lower concentration of BAP (1.0 or 2.0 mg/l). Similarly, the culture of TTC identified embryonic axes did not produce plantlets, but rather significantly long pseudoradicles were produced with BAP having significant effect on pseudoradicle development. Contrastingly, in vitro culture of excised rudimentary shoots on the same MS medium modified with BAP and naphthaleneacetic acid (NAA) produced plantlets with distinct shoots and leaves. Significant reduction in days to emergence of seedlings from deshelled seeds and successful in vitro plantlet development using rudimentary shoot explants will enhance nursery establishment of this economically important tree species for domestication and reafforestation programmes in sub-Saharan Africa.Item High insecticide resistance intensity of Anopheles gambiae (s.l.) and low efficacy of pyrethroid LLINs in Accra, Ghana(Parasites & Vectors, 2019-06-05) Dadzie, S.K.; Pwalia, R.; Joannides, J.; Iddrisu, A.; Addae, C.; Acquah‑Baidoo, D.; Obuobi, D.; Amlalo, G.; Akporh, S.; Gbagba, S.; Athinya, D.K.; Hadi, M.P.; Jamet, H.P.; Chabi, J.Background: Insecticide resistance of Anopheles gambiae (s.l.) against public health insecticides is increasingly reported in Ghana and need to be closely monitored. This study investigated the intensity of insecticide resistance of An. gambiae (s.l.) found in a vegetable growing area in Accra, Ghana, where insecticides, herbicides and fertilizers are massively used for plant protection. The bioefficacy of long-lasting insecticidal nets (LLINs) currently distributed in the country was also assessed to delimitate the impact of the insecticide resistance intensity on the effectiveness of those nets. Methods: Three- to five-day-old adult mosquitoes that emerged from collected larvae from Opeibea, Accra (Ghana), were assayed using CDC bottle and WHO tube intensity assays against different insecticides. The Vgsc-L1014F and ace- 1 mutations within the population were also characterized using PCR methods. Furthermore, cone bioassays against different types of LLINs were conducted to evaluate the extent and impact of the resistance of An. gambiae (s.l.) from Opeibea. Results: Anopheles gambiae (s.l.) from Opeibea were resistant to all the insecticides tested with very low mortality observed against organochlorine, carbamates and pyrethroid insecticides using WHO susceptibility tests at diagnostic doses during three consecutive years of monitoring. The average frequencies of Vgsc-1014F and ace-1 in the An. gambiae (s.l.) population tested were 0.99 and 0.76, respectively. The intensity assays using both CDC bottle and WHO tubes showed high resistance intensity to pyrethroids and carbamates with survivals at 10× the diagnostic doses of the insecticides tested. Only pirimiphos methyl recorded a low resistance intensity with 100% mortality at 5× the diagnostic dose. The bioefficacy of pyrethroid LLINs ranged from 2.2 to 16.2% mortality while the PBO LLIN, PermaNet ® 3.0, was 73%. Conclusions: WHO susceptibility tests using the diagnostic doses described the susceptibility status of the mosquito colony while CDC bottle and WHO tube intensity assays showed varying degrees of resistance intensity. Although both methods are not directly comparable, the indication of the resistance intensity showed the alarming insecticide resistance intensity in Opeibea and its surroundings, which could have an operational impact on the efficacy of vector control tools and particularly on pyrethroid LLINs. Keywords: Anopheles gambiae (s.l.), WHO susceptibilityItem Identity, fashion and exchange: Pottery in West Africa(Azania Archaeological Research in Africa, 2011-04) Haour, A.; Manning, K.; Bakinde, C.; Iddrisu, A.; Saako, M.Item The Morphological And Syntactic Functions Of Dagbani Nominal Suffixes(Topics in Linguistics, 2023) Hudu, F.; Iddrisu, A.One of the defining morphological properties of nouns and adjectives of Dagbani (a Gur/Mabia language) of northern Ghana) and related languages is the presence of suffixes that mark number (singular or plural) as well as serve as the basis for noun classification. The typical regular noun or adjective (e.g. bi-a ‘a child’) consists of a bound root (bi-) providing the lexical meaning and a suffix (-a), which indicates the singular number of the noun. In plural form, the suffix is replaced by a different one. marks plurality (bi-hi). In this paper, we show that while this broad description is generally accepted, is much weaker than assumed in previous studies, with many inconsistencies. As our main goal, we offer a much broader analysis of the morphological and syntactic functions of the nominal suffixes. We show that these suffixes are primarily there to project lexical words as nouns and adjectives and should be referred to as nominal suffixes used to inflect inherent nouns and derive nouns and adjectives from verbs. The nominal suffixes are also crucial to distinguishing between different compound nouns and nouns. phrases. The paper is largely descriptive, with no specific theoretical approach assumed.Item Observations on seed embryo and germination, seedling morphology and development of Vitellaria paradoxa (C. F. Gaertn.)(Observations on seed embryo and germination, seedling morphology and development of Vitellaria paradoxa (C. F. Gaertn.), 2019-02) Iddrisu, A.; Elegba, W.; Klu, G.Y.P.; Danso, K.E.Cotyledon morphology and subsequent establishment of V. paradoxa seedlings that account for its cryptohypogeal germination were studied. To identify the embryonic axis, fresh and partially dry seeds were deshelled and their distal ends transversely cut off. Cut seeds were immersed in 1.0 % tetrazolium chloride (TTC) solution for 24 hours and kept in the dark for staining. To study cotyledon morphology, 50 seeds were deshelled, air-dried for 3–5 days and split open from the distal end. Another batch of 50 seeds were sown directly. The sprouted seeds or seedlings were sampled at 5-day intervals and their cotyledonary tubes sectioned to observe morphological and anatomical features. Morphologically the seed bears a cotyledonary raphe, which lies vertically with distally schizocotylous and proximally syncotylous cotyledons. Large seeds sprouted earlier (7 days) followed by seedling emergence within 61 days, while small seeds sprouted almost a week later (12 days) with seedling emergence within 75 days. The location of the embryos at the proximal ends cause germinating seeds to produce long cotytedonary tubes which bury the plumules deep into the soil, a protection against bushfires. This germination study will enhance nursery establishment for plantation development of V. paradoxa.Item Old tractors, new policies and induced technological transformation: agricultural mechanisation, class formation, and market liberalisation in Ghana(Taylor & Francis Group, 2022) Amanor, K.S.; Iddrisu, A.This article examines the recent uptake of tractor ploughing services in northern Ghana. It examines the historical continuities in mechanisation and the emergence of a class of medium-scale commercial farmers. In the light of this, it questions the thesis that the recent uptake of mechanisation and emergence of medium scale farmers reflects the successes of market liberalisation. It is critical of neoclassical theories of agricultural transformation rooted in theories of induced innovation and argues for a political economy approach that links agricultural transformation to processes of social differentiation and the historical role of the state in promoting agricultural commercialisation.