Cavendish bananas are the most important sub-group of all bananas. They includes more than 30% of the global banana production and almost all bananas exported are of the Cavendish type. This sub-group is also an important food source. Most of the fruit is consumed locally, such that only 35% enters the international market. To meet the regular demand for domestic consumption and market supply there must be a reliable production strategy. The technique of tissue culture is a better option than conventional propagation techniques. However. the high incidence of somaclonal variation among plants derived from tissue culture is a problem for commercial producers. Several factors such as genotype, tissue source, duration in culture, and the tissue culture technique employed, cause somaclonal variation. The impact of plant growth regulators on somaclonal variation was studied on Cavendish banana cv. 'Zelig' obtained from African Biotechnologies Ltd., South Africa. In vitro grown plants at the 4th multiplication cycle were supplied for the investigation. The first component of the investigation dealt with the effect of types of plant growth regulators. Combinations of the auxins IAA, IBA and NAA with the cytokinins BA and TDZ were used to culture the plants for ten multiplication cycles. Plants were then randomly selected to collect leaf material for DNA extraction and RAPD analysis. The second aim of this study was to investigate the effect of the cytokinin BA on plantlets subcultured over 5-10 multiplication cycles. The auxin IAA at the concentration of 2 mgl-1 was combined with BA at concentrations of 2.5, 5.0 and 7.5 mgl-1. Plants were analyzed at each level of subculture from the 5th to the 10th cycle for respective cytokinin concentrations. Plants were then randomly selected for the collection of leaf material for DNA extraction and RAPD analysis. DNA was extracted from leaf tissue of in vitro grown plants using a modified CTAB extraction procedure. DNA amplification products were scored for the presence and absence of bands in a particular locus. Results were clustered according to their similarities. The relationship between multiplication rate and variation was assessed using correlation analysis. Results of the investigation showed that treatments with higher multiplication rates produced higher rates of variation. A variation rate of 55% was recorded for treatments containing IAA and BA. A higher rate of variation (72%) was identified in the treatment with IAA (2mgl-1) plus BA (7.5 mgl-1) over 10 cycles. In all cases the dwarf off-type was the most common type of variant obtained, contributing 87.7% of the total amount of variation. The dwarf specific marker (OPJ-041500) reported previously in Williams Cavendish was identified in cv. 'Zelig' in this study. Another band similar in size was amplified by primer OPC-15 and named OPC-151500 . This band consistently appeared in all the normal plants and was absent in all the dwarf types and hence could be used as a dwarf specific marker. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2004.

Mozambique has potential to boost its banana exports. To fully realise this, agronomic practices in production should be fully developed to combat physiological disorders associated with banana within the region. Currently, lower temperatures are being experienced in some production sites, consequently affecting yield and quality. The objective of this study was to evaluate use of bunch protection covers on banana cultivars Grand Nain and Williams banana cultivars, for performance under different fruit protection materials to determine best fruit protection bag suitable for Metocheria, Nampula. Plants were not selected near plantation borders, drainage canals, cable way and roads, as this would influence the growth pattern of plants and fruit development. Treatments consisted of control (no bag on bunches), white perforated polyethylene, white non-perforated polyethylene, blue perforated polyethylene, blue non perforated polyethylene, green perforated polyethylene, green polyethylene non perforated and cheese cloth bags arranged in a complete randomised block designed CRBD with 26 plants replicated eight times. During 2012/2013, bagging treatments did not considerably improve weight in hands, banana finger weight, total fruit weight, marketable weight and percentage marketable fruit weight and box stem ratio (BSR) of Grand Nain. However there was reduction of fruit defects in all bagging treatments compared to control (no bags). In Williams during the 2013 season bagging treatments improved weight but no significant differences were observed on weight of hands in 2012. Bagging of banana bunches reduce defects in both seasons. Both green and blue perforated bags improved box stem ratio. Bagging treatments increased Williams‟s cultivar yield (per ton) in both seasons / Agriculture and  Animal Health / M. Sc. (Agriculture)

Mozambique has potential to boost its banana exports. To fully realise this, agronomic practices in production should be fully developed to combat physiological disorders associated with banana within the region. Currently, lower temperatures are being experienced in some production sites, consequently affecting yield and quality. The objective of this study was to evaluate use of bunch protection covers on banana cultivars Grand Nain and Williams banana cultivars, for performance under different fruit protection materials to determine best fruit protection bag suitable for Metocheria, Nampula. Plants were not selected near plantation borders, drainage canals, cable way and roads, as this would influence the growth pattern of plants and fruit development. Treatments consisted of control (no bag on bunches), white perforated polyethylene, white non-perforated polyethylene, blue perforated polyethylene, blue non perforated polyethylene, green perforated polyethylene, green polyethylene non perforated and cheese cloth bags arranged in a complete randomised block designed CRBD with 26 plants replicated eight times. During 2012/2013, bagging treatments did not considerably improve weight in hands, banana finger weight, total fruit weight, marketable weight and percentage marketable fruit weight and box stem ratio (BSR) of Grand Nain. However there was reduction of fruit defects in all bagging treatments compared to control (no bags). In Williams during the 2013 season bagging treatments improved weight but no significant differences were observed on weight of hands in 2012. Bagging of banana bunches reduce defects in both seasons. Both green and blue perforated bags improved box stem ratio. Bagging treatments increased Williams‟s cultivar yield (per ton) in both seasons / Agriculture and  Animal Health / M. Sc. (Agriculture)

Reduced banana yield owing to black Sigatoka Mycosphaerella fijiensis Morelet is a threat to the livelihoods of Ugandan subsistence farmers who depend entirely on the banana crop for food security. The objectives of this investigation were to: (i) assess farmers’ knowledge of black Sigatoka disease in central Uganda; (ii) document the qualities farmers would desire in the banana genotypes to be developed for black Sigatoka resistance; (iii) appraise the methods for assessing black Sigatoka resistance in diploid banana populations; (iv) determine the phenotypic variation for black Sigatoka resistance and agronomic traits in diploid and tetraploid bananas; (v) determine the influence of tetraploid and diploid parents on the black Sigatoka resistance and agronomic traits in the triploid progenies; and (vi) evaluate 2x by 2x banana progenies for yield and black Sigatoka resistance. A survey that focused on low and medium banana production zones in Uganda established that there was limited awareness of black Sigatoka disease as a constraint on banana production in the areas surveyed. It was also established that farmers liked local bananas because of their superior taste, early maturity, and marketability. There were farmers who had been exposed to new black Sigatoka resistant materials but never liked these new banana materials because of poor taste and lack of market. Farmers desired new banana materials with good taste on cooking, heavy bunches, resistance to pests and diseases, drought tolerance, and early maturing capacity in that order. The results indicated that the banana farmers in Uganda attached more importance to food quality attributes than to production attributes especially when considering new banana materials. This suggested that farmers mainly grow bananas for consumption. Three black Sigatoka assessment methods, youngest leaf spotted, disease development time and area under disease progress curve (AUDPC) were appraised using a diploid population. All the three methods were able to classify the diploid accessions into resistant and susceptible clones. The cultivar rankings of AUDPC correlated strongly with the rankings of disease development time. The cultivar rankings of AUDPC correlated positively with the rankings of youngest leaf spotted method. The youngest leaf spotted at flowering and AUDPC predicted significantly total number of leaves at flowering (R2 = 0.53). Overall AUDPC had the highest coefficient of determination (R2=0.84) in assessment of banana diploids for black Sigatoka resistance indicating that it accounted for the highest variation in disease response observed among the diploid clones. From this investigation it was recommended that AUDPC should be used to assess resistance on black Sigatoka in Musa species. A phenotypic analysis on the diploid and synthetic tetraploids, and a molecular analysis using RAPD markers on the tetraploid population were conducted. Results indicated that the diploid population had significant (P<0.001) variation for plant height, plant girth, days from flowering to harvest, bunch weight, number of suckers, youngest leaf spotted, total leaves at flowering, area under disease progress curve, and number of functional leaves at harvest. Principal component analysis showed that plant height and girth explained most of the variation observed in the diploid population. In the tetraploid population, significant differences were observed for plant height, plant girth, and number of suckers (P<0.05). In the tetraploids principal component analysis, indicated that youngest leaf spotted and total leaves at flowering had higher loadings on principal component one. Genetic distances computed from RAPD markers indicated limited genetic variability in the tetraploid population. Another investigation was also carried out to determine the influence of tetraploid and diploid parents on black Sigatoka resistance and agronomic traits in the triploid progenies generated from tetraploid-diploid crosses. The results indicated that diploids transferred black Sigatoka resistance to triploid progenies as measured by disease development over time, the number of functional leaves at flowering and at harvest. On the other hand, the female synthetic tetraploids influenced plant height and bunch weight in the triploid progenies generated from tetraploid-diploid crosses as observed from triploid progeny correlations and parent-offspring regressions. Therefore, it is important to select tetraploids with heavy bunch weights to generate high yielding triploids in tetraploid-diploid crosses. Lastly, this thesis investigated the relationship between bunch weight and black Sigatoka resistance traits in 2x by 2x progenies generated using a random polycross design. Phenotypic correlations revealed strong positive relationships between bunch weight with total leaves at flowering, youngest leaf spotted, plant girth, and days from planting to flowering among the 2x by 2x progenies. Linear regression analysis indicated that girth, total fingers and finger length significantly predicted bunch weight (R2=0.67). However, days from planting to flowering, and total leaves at flowering had strong indirect effects on bunch weight via plant girth. The results imply that selection for parents with good combining ability for girth, finger length and total fingers can improve bunch weight in a diploid population. / Thesis (Ph.D.) - University of KwaZulu-Natal, Pietermaritzburg, 2009.