https://cris.library.msu.ac.zw//handle/11408/144 Sat, 18 Apr 2026 08:08:07 GMT 2026-04-18T08:08:07Z https://cris.library.msu.ac.zw//handle/11408/3686 Title: Effects of different bio-fumigants on the control of root-knot nematodes (Meloidoygne javanica). Authors: Paskwavaviri, Netsai Sharon Abstract: Root-knot nematodes are one of the major economically important pests causing yield losses of up to 80% in many regions of the world including Zimbabwe. Control of nematodes has been mainly based on use of synthetic nematicides and these have negative impacts on the environment, as a result there is growing interest in alternative methods of management that are economically viable and non-polluting such as Bio-fumigation. An In vitro experiment was carried out in the 2018/19 growing season at Horticulture research Centre to investigate the use of different bio-fumigants (Brassica juncea, Brassica carinata, purple stem Cleome gynandra and green stem Cleome gynandra) at varying rates of 3, 5 and 10grams on the control of root-knot nematodes. The experiment was laid out as a 4×3 plus 1 factorial arranged in a Compete Randomised Design (CRD) with 13 treatments replicated 4 times. Nemacure®400Ec at 0.5ml/10mls water was used as a positive control. 100 juveniles of Meloidogyne javanica pure culture was obtained from Tobacco Research Board and were exposed to the different treatments and data was collected on the number of dead juveniles and number of eggs. Results show that there was significant interaction (p≤0.01) on the effects of bio-fumigants and rates on nematode mortality Brassica juncea at 10grams recording the highest juvenile mortality when compared to other bio-fumigants. There was no interaction (p≤0.09) between bio-fumigant type and rates on number of nematodes eggs. However, there was significant (p≤0.01) difference on the effect of the individual factors on number of nematode eggs recorded. Brassica juncea recorded the least number of nematode eggs followed by Brassica carinata, purple Cleome gynandra and green Cleome gynandra respectively. There was significant (p≤0.03) difference on the efficacy of different bio-fumigants rates on number of nematode eggs with 10grams recording the least number of eggs. Volatile compounds (ITCs) Isothiocynates produced from the hydrolysis of glucosinolates in plant tissue could have contributed to juvenile mortality and reduction in number of eggs recorded. It can therefore be concluded that use of Brassica juncea at 10grams as a bio-fumigant could be an alternative way of controlling root-knot nematodes. Mon, 01 Jan 2018 00:00:00 GMT https://cris.library.msu.ac.zw//handle/11408/3686 2018-01-01T00:00:00Z Paskwavaviri, Netsai Sharon https://cris.library.msu.ac.zw//handle/11408/3274 Title: Genotype × environment interaction studies on the performance, adaptability and stability of pre- release flue-cured tobacco hybrid lines in Zimbabwe Authors: Chikwature, Nyasha Abstract: The nature and magnitude of the genotype × environment interactions is important to identify superior and stable genotypes under target environments. This will assist to maximize specific adaptation and to speed up the distribution of new cultivars to growers. Eleven pre-release flue cured tobacco hybrid lines were evaluated for yield and quality in four different tobacco growing regions thus, Kutsaga and Rusape representing the slow growing areas, Trelawney representing the medium growing areas and Tengwe representing the fast growing areas . The thrust of this study was to assess the stability and adaptability of these hybrid lines. KRK 26R was used as a positive check line because it is a cultivar that is adaptable and stable to a wide range of environments. The hybrid lines were raised with the new float tray system of seedling production and all cultural practises were done following the TRB handbook recommendations. Significant genotype × environment variations were observed among the hybrid lines. For the total saleable yield, environmental high significant difference was observed (P = 0.001), the study revealed that Tengwe had the best yield of 2755kg/ha, while, Kutsaga had the least yield of 1934kg/ha. For the grade index genotypic highly significant difference was observed (P = 0.001) with G9 outperforming all other test genotypes including the check line with an index of 61.74, while, G1 least performed with an index of 51.0. For the top grades proportion Genotype × Environment interaction was found and GGE biplot procedure was followed and results indentified the stability and adaptability of the performance of the hybrid lines. The GGE biplots indentified that G7, G8 and G11 as the high quality and stable genotypes. G1, G2 and G5 least performed and had low stability. It was observed that Kutsaga that is located in the slow growing areas as the ideal testing environment for these set of hybrids that were under test. Mon, 01 Jan 2018 00:00:00 GMT https://cris.library.msu.ac.zw//handle/11408/3274 2018-01-01T00:00:00Z Chikwature, Nyasha