Thesis (M. Sc. (Agronomy)) -- University of Limpopo, 2021 / Cowpea (Vigna unguiculata (L.) Walp) is an important annual leguminous crop grown in arid and semi-arid areas in Sub Saharan Africa. Most of the cowpea production in South Africa is mainly used for domestic consumption and, as seed for planting and little gets to be used in food processing, thus, there is a need to expand the utilization of cowpea through food processing. This study aimed to evaluate cowpea genotypes for phenotypic and canning quality traits. Field experiments were conducted at two locations in Limpopo Province, namely Syferkuil Agricultural Experimental Farm and Ga-Molepo village during the 2017/2018 growing season. The field experiment was comprised of 100 cowpea genotypes laid out in an Alpha Lattice Design replicated twice. Cowpea canning analysis was done using tomato puree following ARC-GC in-house method at the Agricultural Research Council-Grain Crops in Potchefstroom, North West Province of South Africa. Collected data on yield was analysed using Genstat 18th edition and XLSTAT 2021.1.1.1081 software for canning quality data. The results revealed significant differences among the cowpea genotypes based on the number of seeds per pod and 100 seed weight for Syferkuil. Significant differences were also observed among the studied genotypes for 100 seed weight at Ga-Molepo. The highest yield recorded across locations was for genotypes RV 555 (875.4 kg/ha), RV 207 (756,3 kg/ha), RV 439 (694.6 kg/ha) and RV 554 (682.3 kg/ha) respectively. The number of pods per plant recorded a high positive association with pod number per plant and number of seeds per pod. Grain yield of RV 558, RV 556, RV 207, RV 439 and RV 553 was high at Syferkuil and at Ga-Molepo RV 353, RV 194, IT99K-494-6, RV 341 and RV 202 recorded the highest yield. The Principal Component Analysis (PCA) revealed the three most important PCs contributing to a total variation of 76.71%. PC1, PC2, and PC3 contributed 51.01, 13.97 and 11.73%, respectively. For canning ability, out of 79 cowpea canned genotypes, only 11 genotypes were spoiled and had a bad odour. About 68 genotypes were suitable for canning including genotypes that had an excellent appearance without cracks or loose skins and even colour. Furthermore, there was vast variability among the genotypes based on yield and yield components as well as canning quality traits. Genotypes with high grain yield and had canning ability are recommended xi for canning. Data produced from this study will add useful information to the database of the characteristics of these cowpea genotypes.

Thesis (Ph.D. (Plant Production)) -- University of Limpopo, 2022 / Sustainable food production has been a major challenge in the era of climate change and a growing population in the twenty-first century. However, climate change scenarios such as extreme temperatures and fluctuations in annual precipitation continue to pose a great threat to agricultural production systems. On the other hand, anthropogenic activities such as conventional farming continue to contribute to climate change through the emission of greenhouse gases while not sustaining agricultural production. The Food and Agriculture Organization of the United Nations (FAO-UN) developed the concept of Climate-Smart Agricultural (CSA) production with the idea of securing food in the face of global change. No-tillage and intercropping systems are among the traditional practices that are advocated as components of climate-smart traditional practices, especially in the semi-arid regions of Africa like the Limpopo Province. Producing sorghum and cowpeas using CSA practices such as intercropping under no-tillage is envisaged to increase productivity and soil fertility under Limpopo Province's dryland conditions. However, there is still limited information on how grain sorghum-cowpea intercrop will respond in terms of growth, physiological productivity, and carbon dioxide emissions in the system, especially under no-tillage and different growing conditions. Furthermore, more field data is required for predictions of future scenarios using simulating crop models such as the Agricultural Production system sImulator (APSIM). Hence, a no-till Randomized Complete Block Design (RCBD) in a 2 x 4 x 2 factorial arrangement was conducted at two locations (Syferkuil and Ofcolaco) in the Limpopo Province during the 2018/19 and 2020/21 cropping seasons to generate data on sorghum and cowpea growth, physiology, productivity as well as carbon dynamics under planted and simulated intercropping system. Leaf gaseous exchange and leaf area index (LAI) were measured on fully developed grain sorghum and cowpea leaves in both the binary and sole cultures of sorghum and cowpea. The CO2 measurements were taken from each plot using a GMP343 CO2 probe along with an MI70 data logger. Aboveground biomass was collected for each crop from two plants at vegetative, flowering, physiological and harvest maturity and oven-dried at 65 oC for 48 hours. In the 2020/21 cropping season, cowpea at Ofcolaco failed to produce grain. Hence, only the grain yield of the 2018/19 cropping season from Ofcolaco is presented in this thesis. Grains collected for each crop from a 2.7m2 area were taken to the laboratory to determine grain yield and yield components. Harvest index (HI) and land equivalent ratio (LER) for each crop were also determined. In the laboratory, the total nitrogen (%) and natural abundance of 15N (δ15N‰) were determined using an isotope ratio mass spectrometer with an N analyzer. Growth (biomass) and yield (grain) data obtained from APSIM were compared with data collected from a two-year field experiment at Syferkuil. Multi-variate analysis of variance (ANOVA) model to fit each response variable using the Statistical Analysis System (21 SAS version 9.4). Mean separation was done where the means were different using the least significant difference (LSD) at probability levels of p ≤ 0.05. Intercropping system and the density of the companion crop cowpea had a significant (p ≤ 0.05) effect on the physiological responses of sorghum and cowpea, cowpea yield and yield components at the two experimental sites across seasons. However, grain yield and yield components of sorghum were not affected by intercropping or the density of cowpea. Only cultivars of sorghum were significantly different for grain yield and yield components. At Syferkuil, Enforcer produced the highest grain yield of 4338 kg ha-1 in 2018/19, while NS5511 accumulated the highest grain yield of 2120 kg ha-1 during the 2020/21 cropping seasons. At Ofcolaco, Enforcer and Avenger were observed to be relatively high-yielding cultivars with a mean grain yield of 2625 kg ha- 1 and 1191 kg ha-1 during the 2018/19 and 2020/21 cropping seasons, respectively. In the 2018/19 and 2020/21 cropping seasons, respectively, cowpea accumulated about 93% and 77% more grain yield in sole compared to binary culture. At Ofcolaco, about 96% more grain yield was obtained in sole compared to binary cultures during the 2018/19 cropping season. Furthermore, cowpea accumulated over 55% and 49% of grain yield when grown at high compared to low population density at Syferkuil and Ofcolaco, respectively. The investigation on the impact of the intercropping system on CO2 emissions and soil carbon stocks revealed that in 2018/19 at Syferkuil and 2020/21 at Ofcolaco, intercropping systems emitted 11% and 19% less CO2 respectively than the sole cropping systems. In both diverse agro-ecological sites, low cowpea density consistently resulted in higher CO2 emissions than high density. The sorghum-cowpea intercropping system significantly influenced the biological nitrogen fixation of cowpea. Intercropping was found to improve the biological nitrogen fixation of cowpea if a density of 74074 plants ha-1 is used. The APSIM model was able to capture the dynamics of biomass and grain yields in the sole and intercropping system under different densities of cowpea. The findings of this study revealed some useful insights. Firstly, biomass accumulation depended on the cultivar in intercrop as well as the density of cowpea. Secondly, cowpea at a density of 74074 plants ha1 was found to be a good crop to intercrop with grain sorghum as it did not show any significant variation in terms of grain yield and yield components of sorghum. The sorghum cultivar, Enforcer and NS5511 were the best performing cultivars in terms of grain yields at Syferkuil and Ofcolaco. Thirdly, the intercropping system under high cowpea density reduced CO2 emission rates while improving soil nitrogen (N) and carbon stocks. Based on the results of this study, grain sorghum-cowpea intercrop can be adopted as a component of a climate-smart practice to improve crop growth, physiology, as well as productivity compared to sole cropping. However, the grain sorghum cultivar and the density of cowpea should be taken into consideration as they affect the productivity of the two crops. The two seasons data generated from this study was useful in simulating the productivity of intercropping practice using APSIM. However, more field and weather data is required to run long-term simulations on intercropping as a component of the climate-smart method using crop modelling techniques. / National Research Foundation (NRF), Departments of Science and Innovation (DSI) and VLIR-IUC (Belgium)

Malts prepared from sorghum and cowpeas that was germinated at 25°C for 0, 1, 2 or 3 days and dried at 60°C for either 2.5, 5, 7.5 and 10 hours, were evaluated for α-amylase, β-amylase and endo-(1,3)(1,4)-β-D-glucanase activity. Germination had a highly significant effect on enzyme activity (P < 0.01). However, cowpea endo-(1,3)(1,4)-β-D-glucanase was not significantly affected by the combined action of germination and drying. β-Amylase was not detected in any of the samples of this experiment. Further analysis using Duncan’s Multiple Range Test, indicated that there was no significant difference in α-amylase activity in samples dried between 5 to 10 hours. Compared to α-amylase, sorghum and cowpea samples had low endo-(1,3)(1,4)-β-D-glucanase activity. / Master of Science

In Burkina Faso, the existence of different races of Striga gesnerioides (Willd.) Vatke, with apparent variable aggressiveness on cowpea (Vigna unguiculata (L.) Walp) renders the breeding task very complex. Therefore, a number of studies was carried out from 2006 to 2009 in field, pot and ‘’in-vitro’’ to identify new sources of resistance to three prevailing Striga races, SR 1, SR 5 and a newly occurring Striga race named SR Kp and to understand the genetic pattern of the underlying resistance of cowpea germplasm to Striga races found in Burkina Faso. To achieve these objectives, the following investigations were initiated: (i) a participatory rural appraisal (PRA), a participatory variety selection (PVS) and grain quality survey were implemented to identify cowpea breeding priorities for Burkina Faso Striga hot-spots; (ii) the identification of sources of resistance in Burkina Faso germplasm, using three prevailing Striga races of S. gesnerioides as sources of inoculum; (iii) the identification of the mechanisms of resistance underlying the resistance to Striga in such genotypes; (iv) a study of combining abilities of selected parents through a diallel cross; (v) a study of the segregation patterns in crosses involving resistant and susceptible sources and a study of the allelic relationships between different resistance sources. The participatory studies conducted in 2007 and 2008 over three districts in Striga hotspots; there was no effective control method against Striga at farmers’ level. These investigations highlighted the importance of cowpea across all sites. Rain decline over time, low input use coupled with a poor extension system were the major constraints mentioned by farmers. Differential reactions of genotype KVx61-1 for Striga resistance suggested that different Striga races were prevailing in different areas. Farmers’ preferred traits in cowpea genotypes were oriented towards grain quality such as big sized grain, white seed colour and rough texture of cowpea grain, except in Northern-Burkina Faso, where farmers preferred brown-coloured grain for food. Cowpea was also seen as an income generating crop. An evaluation of 108 genotypes was done in 2007 in the field (rainy season) and in pots (off-season) for Striga resistance assessments. The screening trials enabled the identification of sources of resistance to S. gesnerioides. Genotypes KVx771-10, IT93K- 693-2, KVx775-33-2, Melakh and IT81D-994 are potential sources of resistance to all three Striga races with acceptable yield. Landraces were susceptible and late-maturing whilst most wild species were resistant but with unwanted shattering traits. A combining ability study for Striga resistance parameters conducted in pots and a resistance mechanism study conducted ‘’in-vitro’’ were performed using F1 populations from a 10 x 10 diallel cross. The general combining ability (GCA) effects were significant for the resistance parameters Striga emergence date (DSE), Striga height above soil (SH), cowpea grain weight (CGW), hundred grain weight (HGW) for all Striga races involved and Striga vigour (SVIG) for SR 5 and SR Kp. The pot-screening showed that, regardless of the SR used as inoculum, the additive genes were important in conferring Striga resistance for parameters DSE, SH, CGW and HGW. The selection of parents could therefore result in breeding advance. Complete dominance, partial, over-dominance and non-allelic interactions (epistasis or failure of some assumptions) were present for some parameters. The ‘’in-vitro’’ screening showed that additive genes were important, with high narrow sense heritability values for the resistance mechanisms Striga seed germination frequency (GR) for SR 1 and SR Kp, the frequency of Striga radicle necrosis before the penetration in cowpea rootlet (NBP) for SR 5, the frequency of Striga radicle necrosis after the penetration in cowpea rootlet (NAP) for SR 1 and SR Kp and the susceptibility ‘’in-vitro’’ (SIV) for SR 5 and SR Kp. The selection of parents can be useful in accumulating the genes for Striga resistance mechanisms in progenies. The F2 populations derived from crosses between Striga-resistant x susceptible genotypes were evaluated in Striga infested benches in 2008 and 2009. The segregation patterns suggest that single dominant genes govern Striga resistance. The test for allelism showed that two non-allelic genes were responsible for the resistance to S. gesnerioides in cowpea. A new Striga resistance gene seems to be involved in genotype KVx771-10 resistance to S. gesnerioides, which confers resistance to all studied Striga races. Gene 994-Rsg in genotype IT81D-994 which confers Striga resistance to SR 1 and gene Rsg 3 also conferring Striga resistance to SR 1 segregated differently for the resistance to SR 5 suggesting that they were different but both confer resistance to SR 5.

No description available.

Digitized by Kansas Correctional Industries

Thesis (Ph.D.) --University of Limpopo, 2012 / A series of experiments were carried out to evaluate the feeding values of forage sorghum (Sorghum sudanense), cowpea (Vigna ungiculata), lablab (Lablab purpureus) and mucuna (Mucuna pruriens) hays for Pedi goat production in Limpopo Province, South Africa. The first study determined nutrient composition and tannin contents of the forages. The experimental design was a completely randomised design with four treatments: forage sorghum, cowpea, lablab and mucuna hays. All the legume species had higher (P<0.05) protein contents than sorghum hay, ranging from 18 to 22 %. Within the legume species, cowpea hay had a higher (P<0.05) protein content than lablab and mucuna hays. Similarly, lablab hay had a higher (P<0.05) protein content than mucuna hay. Mucuna hay had a higher (P<0.05) concentration of both condensed tannins and hydrolysable tannins than cowpea, lablab and sorghum hays, while lablab hay had the highest (P<0.05) concentration of total polyphenols. The second study determined relative palatability indices of Pedi goats offered forage sorghum, cowpea, lablab and mucuna hays. Four male Pedi goats aged five months and weighing an average of 18 + 2 kg were used. The experimental design was a completely randomized design, with feeds (forage sorghum, cowpea, lablab and mucuna) as treatments and individual animals as replicates. Lablab and mucuna legumes had higher (P<0.05) intake and palatability indices than sorghum and cowpea hays. Palatability indices were positively and significantly (P<0.05) predicted from dry matter intakes of goats (r2 = 0.98). However, there were poor and non-significant (P>0.05) relationships between nutrient contents of the forages and their intake and palatability indices by goats. The third study determined diet intake, digestibility and live weight gain of seven months old Pedi goats fed a basal diet of forage sorghum supplemented with different amounts of cowpea, lablab or mucuna hays. The experimental design was a completely randomized design, with individual animals placed in digestibility crates as experimental units. This study was divided into a series of experiments due to lack of equipment to conduct the whole experiment in one session. A total of four experiments were conducted. Fifteen growing male Pedi goats were used in each experiment, with mean live weights of 15 + 4 kg, 18 + 2 kg, 17 + 3 kg and 20 + 4 kg for experiments 5.1, 5.2, 5.3 and 5.4, respectively. In each experiment, different goats were used. Experiments 5.1 to 5.3 involved cowpea, lablab and mucuna hays, respectively, while Experiment 5.4 compared the levels of supplementation for optimum intake from each of the first three experiments. Dry matter intakes of cowpea and lablab hay were optimised at 39 and 32 %, respectively, while that of mucuna hay increased with increasing levels of mucuna hay supplementation. Dry matter digestibilities of cowpea, lablab and mucuna hays increased with increasing levels of the respective forage supplementations. Cowpea and mucuna hay supplementations improved (P<0.05) final live weights and feed conversion ratios, while goats on lablab hay supplementation lost weight. At optimum intake, goats supplemented with mucuna hay had a better (P<0.05) feed conversion ratio than those supplemented with lablab and cowpea hays. The fourth study determined in vitro gas production of pure and mixtures of forage sorghum with cowpea, lablab and mucuna hays. Two experiments were conducted. In the first experiment (Experiment 6.1) the experimental design was a completely randomised design with four treatments (forage sorghum, cowpea, lablab and mucuna). The legume species of cowpea, lablab and mucuna hays produced more (P<0.05) gas than sorghum hay after 12 hours of incubation. Sorghum hay produced more (P<0.05) gas than cowpea, lablab and sorghum hays after 24, 48 and 72 hours of incubation. Sorghum hay dry matter intake by goats in the palatability trial was positively and significantly (P<0.05) predicted from gas production after 12 (r2 = 0.99), 24 (r2 = 0.97) and 48 (r2 = 0.93) hours of incubation. Cowpea hay, lablab hay and mucuna hay dry matter intakes by goats were poorly predicted from gas production after 12, 24, 48 and 72 hours of incubation. In the second experiment (Experiment 6.2), the experimental design was a completely randomised design with three treatments (mixtures at optimum intake): 1. FS61C39: A mixture of 61 % forage sorghum and 39 % cowpea, 2. FS68L32: A mixture of 68 % forage sorghum and 32 % lablab, 3. FS77M23: A mixture of 77 % forage sorghum and 23 % mucuna. There were no differences in gas production (P>0.05) across dietary mixtures after 12, 24, 48 and 72 hours of incubation. Dry matter intake by Pedi goats of sorghum hay mixed with cowpea at 39 % hay was positively and significantly (P<0.05) predicted from gas production of the mixtures after 24 hours (r2 = 1.0) of incubation. Dry matter intake from gas production from the same mixture was poorly predicted from gas production after 48 (r2 = 0.45) and 72 (r2 = 0.13) hours of incubation. Dry matter intake of sorghum hay by Pedi goats supplemented with lablab hay at 32 % was moderately predicted from gas production after 48 (r2 = 0.67) and 72 (r2 = 0.60) hours, but poorly predicted after 12 (r2 = 0.50), 24 (r2 = 0.53) hours of incubation. Dry matter intake of sorghum hay by Pedi goats supplemented with 23 % mucuna hay was positively predicted from gas production after 12 (r2 = 0.90) hours, but moderately predicted after 24 (r2 = 0.80), 48 (r2 = 0.72) and 72 (r2 = 0.83) hours of incubation. Dry matter digestibility of sorghum hay mixed with 23 % mucuna hay was positively and significantly (P<0.05) predicted from gas production after 24 (r2 = 1.0), 48 (r2 = 0.99) and 72 (r2 = 1.0) hours of incubation. Dry matter digestibility of sorghum hay mixed with 39 % cowpea hay was positively predicted from gas production after 48 (r2 = 0.95), moderately predicted after 24 and 72, and poorly predicted after 12 hours of incubation. Dry matter digestibility of sorghum hay mixed with 32 % lablab hay was positively predicted from gas production after 72 (r2 = 0.92) hours of incubation. The relationships between digestibility of the mixtures and gas production after 12, 24 and 48 hours of incubation were poor. The fifth study determined in sacco degradation of mixtures at optimum intake of forage sorghum mixed with cowpea, lablab or mucuna when incubated in goats. The ‘a’ values and dry matter losses in cowpea and lablab hays were higher (P < 0.05) than those of mucuna hay. Dry matter intake of sorghum hay mixed with lablab hay at 32 % was positively and strongly predicted from in sacco degradation after 12 (r2 = 0.90), 24 (r2 = 0.94), 48 (r2 = 0.96) and 72 (r2 = 0.97) hours of incubation. Dry matter intake of sorghum hay mixed with 39 % cowpea hay was poorly predicted from in sacco degradation after 12 (r2 = 0.25), 24 (r2 = 0.20), 48 (r2 = 0.11) and 72 (r2 = 0.08) hours of incubation. Dry matter intake of sorghum hay mixed with 23 % mucuna hay was positively and moderately predicted from in sacco degradation after 12 (r2 = 0.68) hours and 24 (r2 = 0.55) hours, but poorly predicted after 48 (r2 = 0.40) and 72 (r2 = 0.20) hours of incubation. vii It was concluded that cowpea, lablab and mucuna hays had higher protein contents and palatability indices than forage sorghum and therefore, have the potential of being utilised as protein supplements for goats on low quality roughages. Legume supplementation, in general, improved diet intake, digestibility, feed conversion ratio and live weight of goats, except for lablab hay supplementation. It was also noted that diet intake, digestibility and final live weights of the goats were optimised at different levels of forage supplementation. This may indicate that supplementation levels for optimum productivity will depend on the particular parameter in question. In vitro gas production and in sacco degradation techniques have the potential of predicting intake, digestibility and palatability indices of goats fed sorghum hay supplemented with cowpea, lablab or mucuna hays.

Graduation date: 1993

Consumer preferences for legume cooking properties should be considered at an earlier stage in the breeding process. Hence, we developed an effective, low-cost method to analyze the cooking quality attributes of cowpeas. The objective was to develop a rapid screening method to evaluate the cooking quality attributes of cowpeas (Vigna unguiculata) and compare the results with currently used methods. Soaked samples (five grams) were boiled for 27 min, and seeds and their broth were separated into dishes with covers. Samples were subjectively rated on a 1-5 scale for cooked doneness, tactile texture, aroma intensity, and opacity of the broth. Water absorption, seed splitting, and soluble solid loss were also determined. The samples were evaluated in batches of 25 and replicated three times. Cooking properties showed significant correlations with each other, but did not correlate with raw seed size and color. The method is important because consumer acceptability largely depends on cooking quality in addition to seed appearance. Many properties like cooked doneness and tactile texture were significantly affected by genetics and environment. Compression force determined with a Texture Analyzer (TA) significantly correlated with doneness and tactile texture ratings at -0.67 and -0.69, respectively (P < 0.01). Cooking times from the Mattson bean cooker (MBC) were significantly correlated with doneness and tactile texture at -0.63 and -0.65, respectively (P < 0.05). The Texture Analyzer and MBC confirmed the subjective ratings of cooked doneness and tactile texture. A procedure to determine solid losses using a refractometer, instead of the time-consuming oven-drying method, saved time and has significant promise for use in simple evaluations. The rapid cooking method required 2 hr on the first day and 5 hr on the second day to evaluate 25 samples. The method is efficient, repeatable and uses inexpensive materials compared to the TA and MBC. It also provides descriptive information, and differentiates legume cultivars based on cooking properties. This method is a useful tool in the breeding program for selecting and advancing promising lines. Food processors may also use this method for a quick evaluation to check if their legumes meet required specifications for processing.

Thesis (Ph. D.)--University of California, Riverside, 2008. / Title from first page of PDF file (viewed Febrary 3, 2010). Available via ProQuest Digital Dissertations. Includes bibliographical references. Also issued in print.