Sweetpotato (Ipomoea batatas (L.) Lam.) is an important food crop in East Africa including Kenya. The crop incurs high yield losses in production due to biotic (insect pests and diseases) and abiotic (drought, and heat) constraints. Among abiotic constraints, drought is the most important. Prolonged periods of drought in arid and semi-arid areas of Kenya have led to reduced quantity and quality of sweetpotato storage roots and in severe cases caused total crop failure. The objectives of this study were to: 1) determine sweetpotato production system constraints and farmers’ coping strategies; 2) evaluate sweetpotato clones for yield performance and drought tolerance; 3) analyse genotype x environment interaction and stability for storage root yield of selected clones, 4) determine mechanisms of drought tolerance in sweetpotato, and 5) determine combining ability and heterosis for yield and drought tolerance traits under managed drought stress conditions. To determine the production constraints and farmers’ coping strategies, a survey was conducted in central, eastern and western Kenya. Out of 345 farmers interviewed, 60% were women, and 40% men. Farm sizes ranged from 0.4-0.8 ha, with 90% of sweetpotato cultivated on 0.2 ha or less. The main sweetpotato varieties were Vitaa, Kabonde and Bungoma and the majority of farmer’s used their own conserved planting material which was conserved by leaving them in the field after harvest. About 35% of the farmers identified weevils as the major pest, and sweetpotato virus disease (SPVD) as the major disease, while 28% of the farmers identified drought as a major constraint. The farmers used clean seed, high yielding varieties, high planting density, and manure application as the main strategies to cope with sweetpotato production constraints. Eighty four sweetpotato clones were evaluated under managed drought stress environments at KARI-Kiboko and KARI-Thika. Drought reduced the fresh weight of storage roots (FSR) (72.5%), fresh biomass weight (FB) (74.0%), marketable fresh storage root (MFSR) (80.7%), number of storage roots (NSR) (24.5%), days to permanent wilting point (DPWP) (0.3%), but seemed to increase percent root dry matter (% RDM) (-4.7%), harvest index (HI) (-2.6%), and chlorophyll content (CC) (-2.7%). Across the environments, genotypes 194555.7 (1.06), 421066 (1.05), Chingovu (0.94), 420014 (0.91), Excel (0.9), 199062.1 (0.87) and Unawazambane06-01 (0.81) gave higher FSR yields (kg plant-1) than the local checks. Genotypes Nyarmalo and Polista were among the lowest yielding in the irrigated and non-irrigated conditions. Clones W119, 441725, and Xiadla-xa-kau were the highest yielding under the drought stress conditions. The performance of 24 improved clones was evaluated in replicated trials at KARI-Thika and KARI-Kiboko using 24 sweetpotato clones grown under managed drought stress conditions for two seasons. AMMI, GGE biplots and regression analyses were conducted to determine stability of the clones. Mean FSR was significantly different (P < 0.001) in the two research sites with the environment contributing to 92.7% of the total variation, genotype 1.8%, and interactions 0.4%. AMMI and GGE biplots, and regression indicated the most stable clones to be 441725, Unawazambane06-01 and 189150.1, while Xiadla-xa-kau was the least stable. To gather more information on drought tolerance mechanisms expressed in the sweetpotato genotypes, an experiment was conducted in the greenhouse using clones expressing different levels of drought tolerance in the field. The results showed more under-developed roots (pencil roots) in the drought stressed regimes than in the irrigated regimes and in the drought susceptible genotypes. Drought tolerant genotypes produced more FSR and NSR. The number of vine branches (NVB), vine tip pubescence (VTP) and mature leaf pubescence (MLP) increased with reduction of drought stress however, drought tolerant clones had reduced NVB. Drought stressed clones had shorter basal vine length (BVL), reduced CC, and reduced leaf growth (LG). Drought stress reduced growth of vines in terms of internodes length, internodes diameter, vine length, petioles length, and leaf CC. Overall, for the first time, the study demonstrated that drought stress in the first three months after planting, leads to the proliferation of non-edible pencil roots, which do not become edible storage roots even when drought stress is removed. Therefore, water is critical during this period for improved sweetpotato storage root yield, probably as a drought tolerant mechanism. Combining ability for yield and drought tolerance of 15 F1 sweetpotato families generated through a half diallel mating of six parents was evaluated at KARI-Kiboko in 2012. Significant (P≤0.05) general combining ability (GCA) and specific combining ability (SCA) effects were recorded for root yield in both drought stress and no stress conditions, indicating that both additive and dominance gene effects were important in the inheritance of resistance to drought stress. Progenies from families G2, G5, G7, G8, G10, G12 and G15 had good SCA for fresh storage root yield, total biomass, number of days to permanent wilting point (DPWP), harvest index, and drought stress index (DSI). Progeny 8 from family G4, 5 and 8 from G15, had the highest mid and best parent heterotic effect (117-270%) for fresh storage root yield in both drought stress and no stress conditions. Progeny 6, and 7 from family G10, had the highest mid and best parent heterotic effect (165-234%) for fresh total biomass yield under no drought stress conditions. In conclusion, the progenies from families G2, G5, G7, G8, G10, G12 and G15 that had high yield and biomass specific combining ability under drought and no drought stress indicated that they could be having drought tolerant genes, and therefore could be incorporated into advanced drought screening trials with the aim of releasing the best performing drought tolerant varieties. Secondly, the findings in this study lay a foundation for sweetpotato breeding programmes on drought tolerance. Thirdly, for the first time, this study uniquely combines yield performance, combining ability estimates, days to permanent wilting point and heterosis under contrasting moisture regimes to unmask the gene action of drought tolerance in sweetpotato, a milestone in science. / Thesis (Ph.D.)-University of KwaZulu-Natal, Pietermaritzburg, 2013.

Alternaria leaf petiole and stem blight is an important disease of sweetpotato (Ipomoea batatas (L.) Lam.) causing yield losses in both landraces and improved cultivars. The most important species causing economic yield loss in Uganda are Alternaria bataticola and A. alternate with A. bataticola the most aggressive and widely distributed. The study was conducted to: i) establish farmer-preferred sweet potato attributes, production constraints and Alternaria leaf petiole and stem blight awareness; ii) evaluate Ugandan sweet potato germplasm for Alternaria leaf petiole and stem blight resistance; iii) determine the mode of inheritance of resistance to Alternaria leaf petiole and stem blight and storage root yield components of sweet potato through estimation of the general combining ability (GCA) of the parents and the specific combining ability (SCA) of the parents for each cross; and iv) determine the adaptability and farmer acceptability of selected F1 genotypes across environments. The participatory rural appraisal was conducted to establish farmer preferences and production constraints revealed that farmer preferred sweet-potato traits were high yield, sweetness (taste), early maturity, high dry mass, resistance to pests and diseases, and in-field root storability after maturity. A majority of the farmers considered Alternaria leaf petiole and stem blight a serious production constraint causing yield loss of over 50%. The main control measures against the disease were roguing of infected plants, spraying with fungicides, use of healthy planting materials and planting resistant genotypes. Thirty sweet potato land races and improved cultivars were evaluated for Alternaria blight severity; yield, dry mass, harvest index, sweetpotato weevil (Cylas spp.) damage and sweetpotato virus disease at two sites (Namulonge and Kachwekano) over three seasons (2010B, 2011A, 2011B) under Alternaria inoculum and fungicide spray treatments. Landrace Shock was more resistant to Alternaria blight than Tanzania, the resistant check. Genotypes NASPOT 1, NASPOT 7, New Kawogo and Dimbuka were the most susceptible. Thirty two F1 families were generated from 16 parents in two sets in a North Carolina II mating scheme. The families were evaluated at two sites using a 5 x 7 row-column design with two replications. There were significant (P<0.05) differences among the families in Alternaria blight severity. Both GCA and SCA mean squares (MS) for Alternaria blight were highly significant (P<0.001) but the predominance of GCA sum of squares (SS) for Alternaria blight at 67.4% of the treatment SS versus 32.6% for SCA SS indicated that additive effects were more important than the non-additive effects in controlling this trait. For the yield components, the GCA MS were significant (P<0.05) and accounted for more than 60% of the treatment SS except for percentage dry mass composition where SCA SS accounted for 53.0% of the treatment SS implying that non-additive genetic effects were slightly more important than additive for this trait. Some parents that had desirable high, negative GCA effects for Alternaria blight produced families with undesirable positive SCA effects and the reverse was also true. This implied that the best parents should not be chosen based on GCA effects alone but also on SCA effects of their best crosses. The promising F1 genotypes selected from previously evaluated crosses together with one Alternaria blight resistant check (Tanzania) and one susceptible check (NASPOT 1) were evaluated at three sites (Namulonge, Kachwekano and Serere) using a randomised complete block design with three replications. Scientists and farmers evaluated the agronomic performance and also quality traits of the genotypes before and at harvest. Genotypes G14, G16, G24, G29, G49, G59 and G69 were the most stable across the sites for low Alternaria blight severity and can, therefore, be recommended for further evaluation under both low and high disease pressure areas. Genotypes G67, G13, G14, G24, G29 and G53 were the most high yielding and stable across the sites and were therefore the most widely adapted. In the participatory selection, before harvest and at harvest, Spearman’s rank correlation of the scientists and farmers’ mean ranking of the genotypes at each site was positive and significant. This indicated that the scientists in the study were capable of selecting for farmer preferred traits. / Thesis (Ph.D.)-University of KwaZulu-Natal, Pietermaritzburg, 2012.

Thesis (MScAgric (Horticulture))--Stellenbosch University, 2008. / Sweet cherries (Prunus avium L.) have a high chilling requirement and grow best in areas receiving >1 100 Utah chill units during winter. The main production areas in South Africa, and particularly the eastern Free State, frequently receive insufficient winter chilling and late spring frosts leading to problems of poor budburst, flowering, floral abnormalities and poor fruit set. Research was conducted on the cultivar ‘Bing’ to determine the main factors causing its low fruit set. Various trials were conducted to optimize the timing of rest breaking agents, identify suitable cross pollinizers that flower synchronously with ‘Bing’, and evaluate the influence of temperature and pollen-pistil interactions on fertilization and fruit set. Pollen biology studies using 2- to 3-year-old ‘Bing’ sweet cherry trees were conducted near Clarens, eastern Free State, during the 2005 and 2006 seasons to determine the most suitable cross pollinizer/s for ‘Bing’ and to assess the influence of temperature and pollen-pistil interactions on pollen tube growth and ovule longevity. Significant differences in pollen germination (‘rates’ deleted) occurred between pollinizers, although differences were noted in pollen performance on the stigma and style (in vivo) compared to the artificial media (in vitro), indicating a lack of correlation between in vitro germination and in vivo pollen-pistil interactions. Pollen tube growth, following cross pollination, was influenced by pollinizer genotype, temperature, and the number of pollen grains deposited on the stigma. The highest pollen tube growth rates in ‘Bing’ styles were recorded for the pollinizers ‘Black Tartarian’ (2006), ‘Lapins’ and ‘Rainier’ sweet cherry cultivars at temperatures of approximately 21°C. Temperature had the most significant influence on ovule longevity with the lower orchard temperatures extending ovule viability compared to the higher laboratory temperatures, although pollen tube growth rates were also reduced, thus shortening the effective pollination period. Cross pollination was also shown to extend ovule viability. The results indicate that ‘Black Tartarian’, ‘Lapins’ and ‘Rainier’ were the most suitable pollinizers for ‘Bing’. Hand-pollination with pollen from these donors resulted in a several-fold increase in seed set over naturally-pollinated control flowers. It appears that the principle factors causing poor fruit set in ‘Bing’ sweet cherry are premature abortion of the ovule before fertilization and inadequate transfer of sufficient viable pollen under orchard conditions. Rest breaking trials were conducted on 4-year-old ‘Bing’ sweet cherry trees on ‘Gisela® 5’ rootstock near Clarens (28°28’S; 28°19’E, 1860m) and Reitz (28°0’S; 28°28’E; 1717m) in the eastern Free State, South Africa, during the 2005 and 2006 seasons respectively. In 2005 five treatments were evaluated; viz. 1% and 2% Dormex® (hydrogen cyanamide, HCN); 1% Dormex® + 3% mineral oil; and 3% Lift® (thidiazuron and mineral oil) sprayed at three dates (29 July 2005, 5 August 2005 and 12 August 2005) preceding expected the “green-tip” stage of flower development, plus an unsprayed control. In 2006 four treatments were evaluated; viz. 1% Dormex®; 1% Dormex® + 3% mineral oil; 3% Lift® applied on three dates (26 July 2006, 7 August 2006 and 12 August 2006) and an unsprayed control. No interaction was observed between time of application and type of rest breaking agent (RBA). RBAs were effective at improving budburst and yield during both seasons with the time of application of RBAs having the most significant influence on budburst and production efficiency in ‘Bing’ sweet cherry trees. RBAs were most effective at improving vegetative budburst when applied 9 to 16 days before the (‘actual’ deleted) “green-tip” stage of flower development. Floral budburst and yield were increased by 1% Dormex® + 3% mineral oil and 3% Lift®, but results varied between seasons indicating that time of RBA application should be based on chilling accumulation and bud development stage and not based on calendar date. This current research suggests that ‘Bing’ sweet cherry is poorly suited climatically to the current production areas of the eastern Free State and short-term research needs to identify methods of improving chilling and fruit set by means of evaporative cooling and fruit set-enhancing plant growth regulators. Longer term work requires the identification of new, lower chill cultivars with improved climatic adaptation to South African conditions.

Sweetpotato (Ipomoea batatas, L.) is one of the important sources of carbohydrates and economic income in Mozambique. As with most of the food crops in Mozambique, it is usually produced by small-scale farmers under dryland conditions. Despite the importance of the crop, the storage root yields are still low and it is difficult to keep planting material (vines) for the next planting season. One of the major challenges to production is drought stress. Drought stress affects sweetpotato by retarding aboveground growth, reducing total root yield, percentage of dry mass, and reducing the quality of the roots as a result of the increase in damage caused by the sweetpotato weevil (Cylas formicarius). The objective of this study was to identify sweetpotato genotypes tolerant to drought particularly amongst the orange fleshed types which can be used in breeding programmes to improve the drought tolerance of genotypes grown in Mozambique. To this end, 48 genotypes were evaluated in both field and greenhouse studies conducted at Umbeluzi Research Station (26º 03’ S, 32ºC 23’ E; 12 masl) located about 30 km from Maputo city. The field trial was a three replicate, α-design with split-plots. Genotypes were the wholeplot treatment factor and irrigation levels were the sub-plot treatment factor. The three irrigation levels imposed were: nonstressed plants irrigated from planting to 120 DAP; moderately stressed, plants irrigated until 60 DAP; and severely stressed, plants irrigated until 30 DAP. In the greenhouse trial the 48 genotypes were grown in wooden boxes arranged in a two replicate, randomized complete block design. The plants were exposed to water stress from 10 DAP to the end of experiment at 60 DAP. Genotypes were significantly different for all traits, namely: survival %, vine vigour, aboveground biomass, total and commercial root yield, total fresh biomass, harvest index, β-carotene content, % dry mass, dry mass yield, incidence of sweetpotato virus disease, and incidence of weevil damage. Irrigation levels were significant for the traits: survival %, vine vigour, aboveground biomass, total and commercial root yield, total fresh biomass, harvest index, β-carotene content, % dry mass, and dry mass yield. Irrigation levels were not significant for incidence of sweetpotato virus disease and incidence of weevil damage. The genotypes x irrigation levels interaction was significant for: total and commercial root yield, and incidence of weevil damage; and not significant for: survival %, vine vigour, aboveground biomass, total fresh biomass, harvest index, β-carotene content, % dry mass composition, dry mass yield and incidence of sweetpotato virus disease. The mean dry mass yields across irrigation levels of the national breeding lines and introduced genotypes were higher than the landrace genotypes. Most of the national breeding lines had higher β-carotene content than the introduced and landrace genotypes. The landrace genotypes had relatively higher % dry mass composition compared to the national breeding lines. The stress tolerance index (STI) separated the 48 sweetpotato genotypes evaluated in the field trial into three groups: drought tolerant (high STI); moderate drought tolerant (intermediate STI); and drought sensitive (low STI). Under moderate stress, yield potential (Yp) and yield in a stress environment (Ys) were highly significant, positively correlated with Mean productivity (MP), Geometric mean productivity (GMP), Stress tolerance index (STI) and Tolerance index (TOL). Under severe stress the same correlations were reported. Under moderate and severe stress, the correlation between stress tolerance index (STI) and Stress susceptibility index (SSI) was significant and negative. In the greenhouse trial, differences between genotypes in vine length increment, vine diameter increment, leaf width increment and number of nodes vine-1 were significant (P<0.05). Vine length, vine diameter, leaf width and length increments either increased or were reduced due to water stress. Less than 10% increment in vine length (between 25 and 50 DAP) was recorded in MGCl01, Atacama, Cordner, Beauregard, and CN1448-49. Higher than 40% vine length increment was recorded in Jonathan and UNK-Malawi, Naspot, MUSG0614-24, Resisto, K566632, Tainung64, Ejumula and MUSG0623-09. Vine diameter decreased in Manhissane and MUSG0616-18. No change in leaf length in Tacna and Jonathan and in leaf width in Xihetamakote and Resisto-Nairobi was recorded. The longest petiole length at 30 DAP was recorded by Tacna and the shortest by Nhacutse4. The longest internode length was recorded in 199062.1. Similar to petiole length, Nhacuste4 reported the shortest internode length. The highest number of primary vines was recorded by MUSG0608-61 and lowest by Beauregard. Of the 48 genotypes exposed to water stress, 18 survived until the end of the greenhouse experiment at 60 DAP and were therefore considered to be drought tolerant. / Thesis (M.Sc.Agric.)-University of KwaZulu-Natal, 2011.

Made available in DSpace on 2017-07-10T15:14:22Z (GMT). No. of bitstreams: 1 DissertacaoLincolnGerke.pdf: 1910648 bytes, checksum: 6358009ffae74f406d3f40ede319052c (MD5) Previous issue date: 2015-02-27 / The sorghum was investigated as a food source to replace corn and alternative to sugar cane for ethanol production. Experimental in the State University of Paraná- UNIOESTE West station in Rondon-PR, with the hybrid ADV 2010, which was ensiled and processed with the same equipment already used in the processing of corn and sugarcane, produced a quantity of biomass that exceeded the volume of 165,000 kg of fresh weight per hectare in two sections with an ethanol production of 1,035 liters per hectare in the 1st section and 695 liters per hectare in regrowth, resulting in a cost of R$ 1.26 per liter produced in a rural property. The chemical composition of silage dry matter, acid detergent fiber, neutral detergent fiber, ash and crude protein were relevant in the silage. The results showed that there is viability in producing ethanol from sweet sorghum in rural properties, an additional investment. The economic potential of the material, addition of ethanol and silage extends to the biomass, which can be used for other purposes, and food, can be dried and incorporated into animal feed (fiber) in digesters supply or production steam boilers. / O sorgo sacarino foi investigado como fonte de alimento em substituição ao milho e alternativa à cana de açúcar para a produção de etanol. Na Estação Experimental da Universidade Estadual do Oeste do Paraná-UNIOESTE em Marechal Cândido Rondon-PR, com o híbrido ADV 2010, que foi ensilado e processado com os mesmos equipamentos já usados no processamento de milho e cana, produziu uma quantidade de biomassa que superou o volume de 165.000 kg de massa fresca por hectare em dois cortes, com uma produção de etanol de 1.035 litros por hectare no 1º corte e de 695 litros por hectare no rebrote, resultando num custo de R$ 1,26 por litro produzido em uma propriedade rural. A composição bromatológica da silagem em matéria seca, fibra em detergente ácido, fibra em detergente neutro, matéria mineral e proteína bruta mostraram-se relevantes nas silagens. Os resultados mostraram que há viabilidade em produzir etanol a partir do sorgo sacarino em propriedades rurais, mediante um investimento adicional. O potencial econômico do material, além da produção de etanol e silagem, se estende à biomassa, que pode ser usada para outros fins, além de alimentação, também pode ser secado e incorporado à rações (fibras), em alimentação de biodigestores ou produção de vapor em caldeiras.

Thesis. (M. A. Agriculture (Agricultural Economics)) -- University of Limpopo, 2022 / Food security, poverty and hunger issues, as well as methods of addressing remain a concern for many South Africans. Smallholder farmers' agricultural production is seen as the key to simultaneously alleviating poverty and ensuring food security, especially in rural areas. The sweet potato crop is commonly produced by smallholder farmers in rural areas as a staple in many South African households with the potential to reduce hunger and poverty. Nevertheless, just like other crops, the sweet potato is impaired by external factors such as extreme weather conditions, insects, pests and diseases, thus threatening food security. The most destructive pest to sweet potatoes acknowledged in the literature is the sweet potato weevil (SPW), which can cause between 5-100% in areas where it is not controlled. While there are many SPW control measures Entomopathogenic Nematodes (EPNs) are emerging as one of the Integrated Pest Management (IPM) bio-control techniques that have shown promise in controlling SPW infestations in South Africa and globally. This study conducts a socio-economic analysis of smallholder sweet potato production and analyses the acceptability of EPNs as bio-control measures against the SPW in the Gauteng, Limpopo and North West Provinces of South Africa. This was done through an assessment of farmers‘ knowledge, attitudes, perception and practices (KAPP analysis), exploration of the acceptability of EPNs by farmers, determination of and factors influencing profitability and technical efficiency. Primary data was collected from 119 respondents who were selected through non-probability sampling techniques; purposive, census, and snowball. The analytical tools used to analyse the data were descriptive statistics, Gross Margin Analysis, Multiple linear regression model, Data Envelopment Analysis (DEA) and the Tobit regression model. From the results, an average knowledge score of 2.30 based on a 3–point Likert scale revealed that sweet potato farmers are knowledgeable of the SPW, the impacts and the control measures. Despite this level of knowledge, the farmers were impartial about the attitudes and perceptions regarding the SPW and the control measures. This was based on the findings of a 5-point Likert scale, which yielded average scores of 2.53 and 2.74, respectively. The study also revealed that the majority of the farmers prefer the use of indigenous and physical practices to control SPW. With regards to acceptance of the EPNs bio-control innovation towards control of the SPW, a mean Composite Index of Acceptancy (CIA) of 0.77 revealed the willingness of farmers to accept the EPNs as a bio-control measure. A Gross margin of R9 552.37 indicates that sweet potato farming is generally profitable, and this is influenced by socio-economic factors such as marital status, employment status, sweet potato output per cycle and access to machinery. On the other hand, while sweet potato farming was found to be profitable, the DEA score of 0.09 reveals that these farmers are technically inefficient. Their technical inefficiency is influenced by sweet potato output per cycle, gross margins, farm size, and access to credit, employment status, and chemical use. Based on these findings, the study recommends farmers‘ support through capacity development initiatives for the sweet potato farmers with regards to general economics of sweet potato production and marketing to maximise and sustain their revenue generation, as well as their general efficiency. In addition, increased training and awareness of the EPNs and their benefits as bio-control measures towards SPW infestation will work towards changing farmers‘ mindset with regard to SPW control measures. / Department of Social Innovation (DSI) and United States Agency for International Development (USAID)

Thesis (M.Sc. (Horticulture)) --University of Limpopo, 2022 / Worldwide, water scarcity, land degradation and unavailability of agricultural lands have posed serious threats on food security and income generation. Hunger, micronutrient deficiencies and starvation are likely to go up in Africa due to increasing urbanisation and rise in global food prices. As a result, it is important to identify innovative vegetable growing-based strategies, which can increase access to food by utilising the limited space available in rural and urban areas. Therefore, sack gardening technology could be a solution to both the lack of arable land and water scarcity in urban and rural areas. The objective of the study was to determine whether axillary bud number will have an effect on agronomic parameters and yield of sweet potato cv. 'Blesbok' produced using the sack gardening technology. Treatments, namely, 1, 2, 3, 4, and 5 number of axillary buds per stem cutting, were arranged in randomised complete block design, with 10 replicates. One bud (1) was used as a control. Different stem cuttings measuring from 10 to 30 cm long with approximately one (1) to six (6) axillary buds were collected from mature sweet potato plantation at a certified nursery from cv. 'Blesbok'. A total of eight (8) stem cuttings were planted in sacks consisting of growing media mixture of steam pasteurised loam soil and compost (3:1 v/v), 4 on top side of the sack and the remaining four on the side-holes of the sack. Insect pests were scouted and monitored weekly, while diseases were managed using spraying programmes as in commercial sweet potato production systems. Two weeks after transplanting, each plant was fertilised with 5 g nitrogen (N), phosphorus (P), and potassium (K) 2:3:2 (26) + 0.5% Zinc (Zn) + 5% sulphur (S) and 5% calcium (Ca). Number of axillary buds had significant effects on vine length, fresh shoot mass, number of shoots and dry shoot mass contributing 59%, 58%, 45% and 58% in total treatment variation (TTV), respectively, whereas axillary bud numbers had no significant effects on fresh tuberous root mass, chlorophyll content, vine stem diameter, tuberous root diameter, tuberous root length, dry tuberous root mass and number of tuberous roots. Relative to control (one bud), two (2), three (3), four (4), five (5) number of axillary buds decreased vine length, fresh shoot mass and dry shoot mass by 8-37, 30-55 and 26-55%, respectively. However, relative to control (one bud), number of axillary buds increased number of shoots by 8-17%. The quadratic relationship models were explained by 95, 92, 96 and 98% of vine length (VL), number of shoots (NS), fresh shoot mass (FSM) and dry shoot mass (DSM), respectively. In conclusion, findings of the study demonstrated that a single (1) or two (2) axillary bud(s) on stem cuttings of sweet potato CV. „Blesbok‟ showed better results for both yield and growth parameters as compared to three (3), four (4) and five (5) buds. / AgriSETA

LD2668 .T4 1948 D36 / Master of Science

This item was digitized as part of the Million Books Project led by Carnegie Mellon University and supported by grants from the National Science Foundation (NSF). Cornell University coordinated the participation of land-grant and agricultural libraries in providing historical agricultural information for the digitization project; the University of Arizona Libraries, the College of Agriculture and Life Sciences, and the Office of Arid Lands Studies collaborated in the selection and provision of material for the digitization project.

This item was digitized as part of the Million Books Project led by Carnegie Mellon University and supported by grants from the National Science Foundation (NSF). Cornell University coordinated the participation of land-grant and agricultural libraries in providing historical agricultural information for the digitization project; the University of Arizona Libraries, the College of Agriculture and Life Sciences, and the Office of Arid Lands Studies collaborated in the selection and provision of material for the digitization project.