Thesis (Ph.D.)-University of KwaZulu-Natal, Pietermaritzburg, 2007. / Submitted to the African Centre for Crop Improvement. Full text also available online. Scroll down for electronic link.

Pigeon pea [Cajanus cajan (L.) Millspaugh] is a very important grain legume crop for food, cash and firewood in Malawi. However, its production is affected by Fusarium wilt (Fusarium udum Butler), which causes up to 100% yield loss. The deployment of resistant varieties would be an economical way to manage the disease, and for this, more information is needed on farmers' preferences for local landraces, how farmers and consumers can be involved in developing new varieties resistant to wilt disease, and the genetics of inheritance of resistance. This information would be used to devise a breeding strategy. A participatory rural appraisal was used in the southern region of Malawi to identify pigeonpea production and marketing constraints. Results showed that Fusarium wilt was the most prevalent and destructive disease of pigeonpea in the area. Other constraints included pests, flower abortion, low yields, and low soil fertility. Local landraces accounted for 84% of the pigeonpea production in Malawi. Local landraces were preferred due to their fast cooking time, taste, and the high prices they earn the farmer. Participatory variety selection was used to identify landraces with desirable traits that could be used in the breeding programme. Farmers and buyers selected ten local landraces which were used in the genetic improvement programme. Pigeonpea local landraces and international Crops Research Institute for the Semi-Arid Tropics (ICRISAT) genotypes were evaluated for wilt resistance, yield, and secondary traits at three sites over three seasons. Most of the landraces were susceptible to wilt and late maturing. However, AP10, a local landrace, was high yielding and resistant to wilt and outperformed ICRISAT varieties. This local landrace showed promise for use as a source material for Fusarium wilt resistance in other locally adapted farmer-preferred varieties lacking resistance. The local landraces needed genetic improvement in wilt resistance, yield, early maturity, number of branches and seeds pod. Laboratory and screenhouse studies were performed to develop a new Fusarium wilt screening technique. Grains of finger millet, sorghum, and wheat were tested as media for multiplying F. udum isolates. Pathogenicity tests were done on Bunda College and Bvumbwe Research Station isolates. The Bunda isolate was then used in an infested-seed inoculation technique against eight differential cultivars. The results showed that finger millet, sorghum and wheat were equally effective for rapid multiplication of F. udum isolates. Wheat grain showed the best results for pathogen multiplication and inoculation, due to the large seed size for easy handling. The inoculation process involved placing infested wheat grain on bruised pigeonpea roots and transplanting into soil in pots. The infested seed inoculation technique, which is the first of its kind for pigeonpea, was effective in screening pigeonpea for wilt resistance. The selected landraces were crossed with wilt resistant testers in a 12 lines x 4 testers mating scheme, and 48 F1 crosses were generated. These F1 crosses were evaluated for wilt resistance, yield, and secondary traits. The variations among F1 crosses for wilt and secondary traits were due to additive gene action in both parents and the dominance effects arising from the interactions of parents. Parental lines, with good combining ability effects for wilt resistance (AP2, AP3, and AP4), days to 50% flowering, seed pod, plant height, stem diameter, and number of primary and secondary branches were identified, while ICEAP00554 (tester) was a good general combiner for wilt resistance and days to 50% flowering. These lines would be useful in breeding for Fusarium wilt resistance in farmer-preferred pigeonpea genotypes in Malawi or similar environments. Specific F1 crosses were identified with significant SCAs for wilt resistance, days to 50% flowering, and secondary branches. The significance of GCA and SCA effects, which indicated importance of both additive and non-additive gene effects, respectively, suggested that both selection and hybridisation would be useful to improve the resistance in farmer-preferred varieties. Segregation analyses were conducted on F2 populations to determine the resistance to susceptibility phenotypic ratios. The Chi-square analyses showed that resistance to wilt was dominant over susceptibility in most F2 populations. The segregation ratios of 3:1, 13:3, 15:1, and 9:7 (R:S) indicated that either one dominant gene, or two inhibitory genes, or two independent dominant genes, or two complementary genes, respectively, were conferring wilt resistance in these crosses. Involvement of only a few genes governing wilt resistance suggested few complications, if any, in breeding for this trait in these locally adapted pigeonpeas. The Pedigree breeding method would be recommended for incorporating these traits. / Thesis (Ph.D.)-University of KwaZulu-Natal, Pietermaritzburg, 2007.

Thesis (M.Sc (Plant Production)) --University of Limpopo, 2015 / Information on the performance of the maize and pigeonpea intercropping system under dryland conditions of South Africa is scanty. The aim of this study was to determine the optimum P level and productivity of pigeonpea and maize under the dryland intercropping system. Five P rates (0, 15, 30, 45, and 60 kg P ha-1) were applied to both sole and pigeonpea intercropped with maize in a randomized complete block design with 4 replicates. Growth parameters and yield and yield attributes of pigeonpea and maize were measured to determine performance of both crops. There were significant differences in grain yield of pigeonpea as influenced by P rates in both seasons. Highest grain yields of 781 kg ha-1 during 2009/10 and 894 kg ha-1 during 2010/11 were obtained at P rate of 45 kg ha-1. Cropping system significantly influenced grain yield of pigeonpea in 2010/11 season with 37.1% higher pigeonpea grain yield from intercropped plots than in sole pigeonpea plots. There was 21.8% increase in grain yield of pigeonpea across two seasons as influenced by P rate. Maize grain yield showed little response to P rate only during the first season. However, highest maize grain yield of 1699 kg ha-1 was obtained at 60 kg P ha-1 during the 2009/10 season. Maize grain yield was only significantly influenced by cropping system during the 2010/11 season where sole plots achieved higher grain yield of 4148 kg ha-1 compared to 3297 kg ha-1 from intercrop plots. The results revealed that P application increased grain yield of pigeonpea significantly, especially in intercropped plots. The calculated total land equivalent ratio (LER) for the two crops gave positive and higher than one values, which suggests a favourable grain yield advantage for maize/pigeon pea intercrop.

Orientadores: Anete Pereira de Souza, Liana Jank / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-08-16T21:01:44Z (GMT). No. of bitstreams: 1 Sousa_AdnaCristinaBarbosade_D.pdf: 46726921 bytes, checksum: 60ae5b770dc5cf0bdfbd91ea55920e41 (MD5) Previous issue date: 2010 / Resumo: As pastagens cultivadas, utilizadas em pastejo, constituem a forma mais econômica de fornecer alimentação abundante e de qualidade aos animais. Entre as principais forrageiras cultivadas, está a gramínea Panicum maximum Jacq. que ocupa uma posição de destaque na pecuária brasileira por apresentar elevada produção e qualidade, ser facilmente propagada por sementes e altamente palatável ao gado. As leguminosas forrageiras também são importantes não só pela qualidade e quantidade de forragem produzida, mas também pela fixação de nitrogênio atmosférico e transferência às gramíneas associadas, reduzindo os custos de produção. Entre elas citamos, Cajanus cajan (L.) Millsp., Centrosema pubescens Benth. e Calopogonium mucunoides Desv. Apesar de estas forrageiras terem sido estudadas dos pontos de vista morfológico e agronômico, conhecimentos genéticos ainda são limitados. A caracterização do sistema reprodutivo e o conhecimento da extensão da variabilidade genética contida dentro dos bancos de germoplasma podem auxiliar no planejamento de estratégias para maximizar os ganhos genéticos em programas de melhoramento. Nesse contexto, foram utilizados marcadores microssatélites para estimar a diversidade genética de acessos do banco de germoplasma de P. maximum, C. cajan, C. pubescens e C. mucunoides. Foram desenvolvidos 75 marcadores microssatélites polimórficos para P. maximum, 26 para C. pubescens, 23 para C. mucunoides e para C. cajan foram selecionados 43 microssatélites da literatura. Os resultados mostraram a eficiência desses marcadores para estimar a diversidade genética intra e interespecífica, obtida através de similaridades genéticas. Foi possível observar a formação de grupos bem definidos entre os acessos dessas espécies e adicionalmente, a transferibilidade desses marcadores específicos para outras espécies de forrageiras tropicais. Considerando o potencial de C. pubescens e C. mucunoides para as pastagens cultivadas brasileiras, o sistema reprodutivo dessas espécies foi caracterizado com os microssatélites desenvolvidos. A taxa de cruzamento encontrada para C. pubescens foi de 26% e para C. mucunoides foi de 16%, mostrando que ambas as espécies apresentam um sistema misto de reprodução com predominância de autogamia. Esses dados devem ser considerados durante a multiplicação de sementes para manutenção do banco de germoplasma, a fim de manter a integridade individual de cada acesso. O conhecimento da estrutura genética da população de uma espécie, aliado ao conhecimento de outras características biológicas de interesse, pode fornecer subsídios para programas de conservação do germoplasma, manejo sustentável, domesticação e melhoramento genético da espécie. Os marcadores microssatélites desenvolvidos nesse trabalho, a caracterização da diversidade genética e a taxa de cruzamento são resultados fundamentais, promissores e consistentes para uso no melhoramento, podendo contribuir de forma eficiente na seleção e uso dos recursos genéticos disponíveis. / Abstract: Cultivated pastures used for grazing, are the most economical way to provide abundant high quality feed to animals. Among the main fodder crops, the grass Panicum maximum Jacq. occupies a prominent position in the Brazilian livestock industry by presenting high yield and quality, being easily propagated by seeds and highly palatable to livestock. The legumes also are important not only due to the quality and quantity of fodder produced, but also due to fixation of atmospheric nitrogen and transfer to the associated grasses, reducing production costs. Among them, Cajanus cajan (L.) Millsp., Centrosema pubescens Benth. and Calopogonium mucunoides Desv. Although these forages have been studied from the morphological and agronomic standpoint, genetic information is still limited. The characterization of the reproductive system and the knowledge of the extent of genetic variability contained within the germplasm banks can assist in planning strategies to maximize genetic gains. In this context, microsatellite markers were used to estimate the genetic diversity of germplasm banks of selected accessions of P. maximum, C. cajan, C. pubescens and C. mucunoides. Seventy-five polymorphic microsatellite markers were developed for P. maximum, 26 for C. pubescens, 23 for C. mucunoides and for C. cajan 43 microsatellites were selected from the literature. The results showed the efficiency of these markers to estimate the intra and interspecific genetic diversity obtained through genetic similarities. It was possible to observe the formation of welldefined clusters among the accessions within these species and in addition, the transferability of these specific markers to other species of tropical forages. Considering the potential of C. pubescens and C. mucunoides for the Brazilian cultivated pastures the reproductive system of these species were characterized with the microsatellites developed. The outcrossing rate was 26% for C. pubescens and 16% for C. mucunoides, showing that both species have a mixed mating system with predominance of autogamy. This information should be considered during the multiplication of seeds for maintenance of the germplasm bank, in order to conserve the integrity of each individual genotype. Knowledge of the genetic structure, together with other biological characteristics of interest can provide support to germplasm conservation programs, sustainable management, domestication and breeding of the species. The microsatellite markers developed in this research, the characterization of the genetic diversity and crossing rates are fundamental results, both promising and consistent to be used in breeding and may contribute to the efficiency of selection and use of the available genetic resources. / Doutorado / Genetica Vegetal e Melhoramento / Doutor em Genetica e Biologia Molecular

The plasmids pDN211 and pDNll, isolated from the gene bank of the Rhizobium japonicum strain I-110, have been reported to complement two different Nif+ Hup· (nitrogen fixation positive and hydrogen uptake negative) mutants. A 5.9-kb Hindiii DNA fragment of the cosmid pHU52, isolated from the gene bank of R. japonicum strain 122DES, has been reported to code for the two polypeptide subunits of uptake hydrogenase. To determine homology between the structural genes of uptake hydrogenase of the two strains, a Southern blot of the Hindiii restriction fragments of the plasmids pDN211 and pDN11 was hybridized to the 5.9-kb Hindiii fragment. A 6.0-kb HindIII DNA fragment of pDN11 was observed to be homologous to the hup DNA probe. Thus, the hup genes of the two Rhizobium strains are conserved. Colony hybridization with the 5.9-kb DNA as the probe was used to detect the homologous hup genes in alfalfa-, chickpea- and pigeonpea- Rhizobium species. These Rhizobium species were also successfully derepressed for uptake hydrogenase in free living conditions. It was found that 30% of the alfalfa-, 30% of the chickpea- and 21% of the pigeonpea- Rhizobium strains tested were Hup+ as determined by the methylene blue (MB) reduction assay. All but one strain of alfalfa- (Celpril Ind. 3623) and one strain of pigeonpea- Rhizobium (IC3282) that showed strong homology to the hup DNA probe also exhibited MB reduction activity. The Hup+ strains of alfalfa- and pigeonpea- Rhizobium produced significantly higher yields as compared to the Hup- strains, whereas those of the chickpea-Rhizobium strains produced significantly lower yields as compared to the Hup- strains. Two of the alfalfa-Rhizobium strains, USDA1024 and CmRm~, exhibited Hup activities greater than any reported previously for this bacterial species. The cosmid-borne hup genes of R. japonicum were successfully expressed in all strains tested but the enzyme activities were very low in alfalfa-Rhizobium compared to those in chickpea- and pigeonpea-Rhizobium species. The relative efficiency of N2-fixation was significantly increased by the transfer of hup genes into the chickpea- and pigeonpea- Rhizobium strains.

Thesis (M.Sc. (Agriculture Agronomy)) -- University of Limpopo, 2020 / Pigeonpea (cajanus cajan [L] Millsp.) is a legume crop which is grown mainly in the Semi-Arid Tropical (SAT) regions and it is mostly cultivated for its edible seeds. It has been identified as a possible substitute crop which can be bought by all people and it can also provide an acceptable amount of nutrition and protein in particular as it is not an expensive source of protein when compared to animal protein. Its ability to tolerate drought and fix atmospheric nitrogen makes it suitable for marginal areas with low rainfall and poor fertility. However, it remains one of the underutilized crops due to limited research on the crop’s diversification and adaptation. Smallholder farmers in the Limpopo Province cultivate landraces pigeonpea varieties that are characterized by late maturity, low grain yield and are sensitive to photoperiod and this makes it difficult for the cultivars to flower early and produce reasonable yield. The objectives of the study were to evaluate the nitrogen fixation, yield and yield components of exotic elite pigeonpea genotypes. The experiment was conducted at the University of Limpopo Experimental farm (Syferkuil) in Mankweng during the 2017/18 growing seasons. The trial was carried out in a Randomized Complete Block Design (RCBD) consisting of three replications. A total of 18 elite pigeonpea breeding lines obtained from ICRISAT in Kenya were planted at an inter-row and intra-row spacing of 1m and 0.5m respectively, in a row of 5m length with an alley way of 2m between the blocks. The standard management practices for pigeonpea were used for weed and insect control. The agronomic data collected included the number of days to first and 50% flowering, the number of days to 90% maturity, canopy width (m), plant height (m), peduncle length (m), number of primary branches, number of pods per plant, pod length (cm), hundred seed weight (g), calcium content, sodium content, magnesium content, phosphorus content, potassium content, iron content, zinc content, proportion of legume N derived from the fixation of atmospheric N2 (%Ndfa), amount of nitrogen fixed and the grain yield (kg.ha-1 ). The generated data was subjected to an analysis of variance using the Statistix 10.0 software. The Least Significance Difference (LSD) was used to separate the means that showed significant differences at an alpha level of 0.05. The results revealed significant differences in nearly all the pigeonpea variables (pod length, number of seed per pod, nutrient elements and the number of primary branches). Across genotypes, the number of days to 50% flowering ranged from 95 to 130 days, while the number of days to 90% maturity ranged from 172 to 220 days, with variety ICEAP 01154-2 being the earliest to flower and mature. Tall plants were observed by variety ICEAP 01541 (2.01m) followed by ICEAP 00902 (1.99m) and ICEAP 00850 (1.90m). Breeding line ICEAP 00673-1 recorded long peduncles with a mean of 0.94m. The number of pods per plant had a range between 56 and 482, while the pod length varied from 2.03 to 8.82cm. Variety ICEAP 00673-1 exhibited the highest number of pods per plant and with longest pods. The 100 seed weight varied from 9.43 to 16.97g among the genotypes. The higher calcium amount was observed in verities ICEAP 00979-1 with an average of 556 mg/L and the highest iron content was observed in ICEAP 01172-2 (14 mg/L). The potassium content ranged between 24 mg/L to 110 mg/L, with the variety ICEAP 00540 having the highest and the variety ICEAP 00850 having the lowest content. The sodium content ranged from 15 to 85.1 mg/L, with the variety ICEAP 01154-2 being the highest and the variety ICEAP 01147-1 having the lowest sodium content. The highest magnesium content was observed in ICEAP 00673-1 (141 mg/L). The phosphorus content ranged from 24.5 to 3.77 mg/L and the highest zinc content was observed in ICEAP 01541 and in ICEAP 00979-1 that had an average of 2.36 and 2.26 mg/L, respectively. The amount of nitrogen fixed from all the varieties ranged from 73.547 to 154.254 kg.ha-1 . The grain yield among the genotypes ranged from 89.24 to 785.29 kg.ha-1 . The top yielding varieties were ICEAP 01159 and ICEAP 00557 with grain yields of 785.29 and 661.51 kg.ha-1 . ICEAP 01159 and ICEAP 00557 are the varieties that produced the highest grain yields and they are recommended for cultivation and breeding purposes. / NRF (National Research Foundation)

Made available in DSpace on 2017-07-10T19:24:33Z (GMT). No. of bitstreams: 1 Danielle Medina Rosa.pdf: 463787 bytes, checksum: 5fb7f12fb417c99757409ef22ba924b2 (MD5) Previous issue date: 2009-02-13 / The use of cover crops on no-tillage system can add several advantages, such as controlling the weeds population. The leguminous species also carry out biological nitrogen fixation, increase nutrients to the soil and bring other benefits. Therefore, this research aimed at testing the leguminous, dwarf mucuna beans, dwarf pigeon pea and stylosanthes on seedling, maize development and the weeds incidence. This trial was carried out in both field and laboratory. On field, the leguminous species were sown in October of 2007 plus a control one (fallow) in 20 parcels of 4 x 5 m plots with five replicates each. The weeds population was recorded at 30 and 60 days after sowing of leguminous. At 90 days, they were grazed and the maize, 15 days after grazing, was planted on waste. The emergence and growth of plants were assessed, besides the weeds incidence during culture development. At the laboratory, after harvest, corn yield and seeds quality were determined. As well as the allelopathy tests on leguminous, so the aerial parts were collected and the aqueous extract of leaves was prepared at concentrations of 1, 2.5, 5, 10 and 20 %, while the control was prepared with distilled water. The extract was applied on seeds of weeds (Ipomoea L., Sida rhombifolia L. and Bidens pillosa) and on maize, with four replications per treatment. The experimental design was completely randomized and the means were compared by Scott-Knott at 5% of significance. The studied cover plants showed efficient control of weeds and did not interfere in a negative way on the maize crop. Actually, it is an alternative to the integrated management of species concerning the summer green manure and crop rotation in no-tillage system for the Western region of Paraná. / A utilização de plantas de cobertura em manejo de sistema plantio direto pode agregar uma série de vantagens, entre elas, o controle da população de espécies invasoras. As leguminosas ainda realizam a fixação biológica do nitrogênio, incrementando este nutriente ao solo, além de outras vantagens. Assim, este trabalho testou as leguminosas mucuna anã, feijão guandu anão e estilosantes, sobre a germinação e crescimento de milho e a incidência de espécies invasoras. O experimento foi realizado em campo e laboratório. Em campo, as espécies leguminosas foram semeadas em outubro de 2007, com uma testemunha (pousio), em 20 parcelas de 4x5 m cada, com cinco repetições. Aos 30 e 60 dias após a semeadura das leguminosas, foram levantadas a população de plantas invasoras. Aos 90 dias, as plantas foram roçadas e o milho semeado 15 dias após a roçagem, sobre os resíduos. As avaliações feitas foram de emergência de plântulas e crescimento de plantas, além da incidência de plantas invasoras durante o desenvolvimento da cultura. Em laboratório, após a colheita, foram determinadas a produtividade e qualidade de sementes e realizados testes quanto ao potencial alelopático do extrato aquoso da parte aérea das leguminosas de cobertura nas concentrações de 1; 2,5; 5; 10 e 20% e uma testemunha com água destilada. O extrato foi aplicado sobre sementes das invasoras corda de viola, guanxuma e picão preto,; e milho, com quatro repetições por tratamento. O delineamento experimental foi inteiramente casualizado e as médias foram comparadas por Scott-Knott a 5% de significância. As plantas de cobertura estudadas apresentaram eficiente controle de plantas invasoras e não interferiram de forma negativa sobre a cultura do milho, sendo alternativa para o manejo integrado de espécies na prática de adubação verde de primavera/verão e rotação de cultura no sistema plantio direto, para a região Oeste do Paraná.

Made available in DSpace on 2017-05-12T14:47:55Z (GMT). No. of bitstreams: 1 Danielle Medina Rosa.pdf: 463787 bytes, checksum: 5fb7f12fb417c99757409ef22ba924b2 (MD5) Previous issue date: 2009-02-13 / The use of cover crops on no-tillage system can add several advantages, such as controlling the weeds population. The leguminous species also carry out biological nitrogen fixation, increase nutrients to the soil and bring other benefits. Therefore, this research aimed at testing the leguminous, dwarf mucuna beans, dwarf pigeon pea and stylosanthes on seedling, maize development and the weeds incidence. This trial was carried out in both field and laboratory. On field, the leguminous species were sown in October of 2007 plus a control one (fallow) in 20 parcels of 4 x 5 m plots with five replicates each. The weeds population was recorded at 30 and 60 days after sowing of leguminous. At 90 days, they were grazed and the maize, 15 days after grazing, was planted on waste. The emergence and growth of plants were assessed, besides the weeds incidence during culture development. At the laboratory, after harvest, corn yield and seeds quality were determined. As well as the allelopathy tests on leguminous, so the aerial parts were collected and the aqueous extract of leaves was prepared at concentrations of 1, 2.5, 5, 10 and 20 %, while the control was prepared with distilled water. The extract was applied on seeds of weeds (Ipomoea L., Sida rhombifolia L. and Bidens pillosa) and on maize, with four replications per treatment. The experimental design was completely randomized and the means were compared by Scott-Knott at 5% of significance. The studied cover plants showed efficient control of weeds and did not interfere in a negative way on the maize crop. Actually, it is an alternative to the integrated management of species concerning the summer green manure and crop rotation in no-tillage system for the Western region of Paraná. / A utilização de plantas de cobertura em manejo de sistema plantio direto pode agregar uma série de vantagens, entre elas, o controle da população de espécies invasoras. As leguminosas ainda realizam a fixação biológica do nitrogênio, incrementando este nutriente ao solo, além de outras vantagens. Assim, este trabalho testou as leguminosas mucuna anã, feijão guandu anão e estilosantes, sobre a germinação e crescimento de milho e a incidência de espécies invasoras. O experimento foi realizado em campo e laboratório. Em campo, as espécies leguminosas foram semeadas em outubro de 2007, com uma testemunha (pousio), em 20 parcelas de 4x5 m cada, com cinco repetições. Aos 30 e 60 dias após a semeadura das leguminosas, foram levantadas a população de plantas invasoras. Aos 90 dias, as plantas foram roçadas e o milho semeado 15 dias após a roçagem, sobre os resíduos. As avaliações feitas foram de emergência de plântulas e crescimento de plantas, além da incidência de plantas invasoras durante o desenvolvimento da cultura. Em laboratório, após a colheita, foram determinadas a produtividade e qualidade de sementes e realizados testes quanto ao potencial alelopático do extrato aquoso da parte aérea das leguminosas de cobertura nas concentrações de 1; 2,5; 5; 10 e 20% e uma testemunha com água destilada. O extrato foi aplicado sobre sementes das invasoras corda de viola, guanxuma e picão preto,; e milho, com quatro repetições por tratamento. O delineamento experimental foi inteiramente casualizado e as médias foram comparadas por Scott-Knott a 5% de significância. As plantas de cobertura estudadas apresentaram eficiente controle de plantas invasoras e não interferiram de forma negativa sobre a cultura do milho, sendo alternativa para o manejo integrado de espécies na prática de adubação verde de primavera/verão e rotação de cultura no sistema plantio direto, para a região Oeste do Paraná.