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- Journal of Applied Science in Southern Africa
- OA African Journal Archive
- Volume 8, Issue 1, 2002
Journal of Applied Science in Southern Africa - Volume 8, Issue 1, 2002
Volume 8, Issue 1, 2002
Source: Journal of Applied Science in Southern Africa 8, pp 1 –10 (2002)More Less
Knowledge of genetic parameters is of paramount importance in designing sound breeding programmes. Genetic and phenotypic parameters are needed in the estimation of breeding values. The objectives of this study were to: estimate genetic parameters for milk, fat and protein yields; determine genetic and phenotypic correlations among these production traits and determine if genetic parameters are the same within lactations in Holstein cattle. A total of 17 598 Holstein 305 day milk records from the Zimbabwe Dairy Services Association were used to estimate heritabilities, variances, covariances and genetic and phenotypic correlations among 305 day yields of milk, fat and protein.
Source: Journal of Applied Science in Southern Africa 8, pp 11 –15 (2002)More Less
With and without hollow cathode cavity behind the cathode aperture, the self breakdown discharge features of the multigap pseudospark (MGPS) are investigated. With a hollow cathode cavity system, a very small and stable erosion pattern by electron-beam generated from MGPS is formed on the opposite surface inside the anode cavity and stable concentric ring-shaped erosion patterns are observed at the central areas around the apertures on the electrodes. Without the hollow cathode cavity, the patterns become irregular and unstable. These results reveal that the hollow cathode cavity plays an essential role in the stability of pseudospark discharges in multigap pseudosparks and to the generation of a well pinched electron-beam. This work was done in October 1997 at Tshingua University in Beijing, China.
A survey on goat production in a semi-arid smallholder farming area situated in the north of ZimbabweAuthor J.F. Kusina, N.T. & KusinaSource: Journal of Applied Science in Southern Africa 8, pp 16 –24 (2002)More Less
A survey was carried out to evaluate goat production in a crop-livestock farming area in the north of Zimbabwe. The objectives of the study were to determine goat production systems and productivity. Qualitative information was obtained using participatory rural appraisal techniques (PRA) while quantitative data was obtained through administration of a structured questionnaire to 317 households. The major finding of the survey indicated that the predominant goat breed found was the small indigenous Mashona goat. The goats were reared exclusively through extensive foraging during the dry season but were herded, tethered or a combination was used during the cropping season. Flock sizes were small, averaging 12 goats/household resulting in few goats available for sale or slaughter. All goat sales were informal. Ninety one percent of farmers indicated interest in cross breeding Mashona does with Boer bucks to improve the size of the Mashona.
Effects of organic and inorganic nitrogen fertilizer on maize (Zea mays L.) nitrogen uptake and nitrate leaching measured in field lysimetersSource: Journal of Applied Science in Southern Africa 8, pp 25 –36 (2002)More Less
Maize (Zea mays L.) production in the smallholder farming areas of Zimbabwe is based on both organic and inorganic nutrient sources. A study was conducted to determine the effect of cattle manure, N fertiliser, and their combinations on nitrate concentration in leachate leaving the root zone and to establish N fertilisation levels which minimise N leaching. Maize was grown for two seasons (1996/97 and 1997/98) in field lysimeters repacked with a coarse-grained sandy soil. Average leachate volumes over the two seasons were similar between different treatments, and ranged from 388 to 418 mm yr-1.
Performance assessment of water delivery to a smallholder irrigation scheme in Zimbabwe: Nyanyadzi case studySource: Journal of Applied Science in Southern Africa 8, pp 37 –51 (2002)More Less
The potential benefits from smallholder irrigation schemes are rarely realised due to unsatisfactory performance of their water delivery systems. A study was conducted to quantify and evaluate water delivery performance indicators of adequacy (Ad), equity (Eq) and dependability (Dp) in three sub-blocks of Nyanyadzi smallholder irrigation scheme using water requirement analysis and a questionnaire survey. The water delivery performance evaluation was carried out between October 1996 and January 1997 for two maize crops under supplementary irrigation and for two consecutive irrigation cycles. Water supply adequacy (ratio of supply to demand) in the first cycle was good (Ad>1.21) and became marginally good (0.96 to 1.01) and poor (Ad<0.74) in the second cycle.
Maize seed orientation in the substrate and its influences on germination, seedling structure, and transmission of Fusarium moniliformeSource: Journal of Applied Science in Southern Africa 8, pp 52 –63 (2002)More Less
The percentage of seedlings emerging during the first 4 days after sowing and the mesocotyl length after 7 days in sand at 25C was strongly influenced by the orientation of the seed in the seedbed. Maize seeds emerged faster when oriented vertically with the pedicel end facing down (VD) or horizontally with the embryal side facing up (HU). The mesocotyl portion of the seedling was shorter (11mm) when sown at HU and VD, providing a fast and easy emergence to the seedling. It was much longer (20mm) when the seed was oriented horizontally with the embryal side facing down (HD) and vertically with the pedicel end facing up (VU). We concluded that the length of the mesocotyl portion of the seedling varies with the orientation of the seed in the substrate at the same depth.