A review of the anatomical literature concerning Arachis hypogaea is presented. Due to the fact that the anatomical work concerning the plant is limited and also to the fact that the work that has been done is often quite old and obscure, a definite need exists for research along this line. / Master of Science

Groundnut (Arachis hypogaea L.) is one of the most important legume crops in Malawi. However, production among smallholder farmers has declined in recent years. One of the constraints affecting groundnut production is groundnut rosette disease (GRD). Therefore, the main objective of this study was to develop appropriate groundnut cultivars that are resistant to GRD, combined with other traits preferred by farmers, in order to improve income and food security of smallholder farmers in Malawi and beyond. The specific aims were; (i) to assess groundnut cropping systems used by smallholder farmers in Malawi, their varietal preferences, and production challenges (ii) to assess the genetic diversity among groundnut germplasm collected from ICRISAT, the Chitedze gene bank and farmers (iii) to identify sources of resistance to GRD and to its aphid vector (iv) and to understand the type of gene action governing GRD resistance, and to identify groundnut genotypes suitable for use as parents in breeding for GRD resistance. Assessment of groundnut cropping systems used by smallholder farmers, their varietal preferences, and production challenges was done by using a field survey and participatory rural appraisal (PRA) tools. The field survey was done in Lilongwe, Mchinji and Salima while the PRA was done in Kasungu, Lilongwe, and Salima. The assessment of genetic diversity among 106 groundnut genotypes collected from ICRISAT, Chitedze gene bank and farmers was done using 19 SSR markers. High throughput DNA extraction was done followed by polymerase chain reactions (PCR) after which the amplified products were analyzed. Evaluation of genotypes to identify new sources of resistance to GRD and its aphid vector was conducted under two test situations, one with high inoculum levels and one with low inoculum levels. Under high inoculum level, the infector row technique developed by Bock and Nigam (1990) which employs a susceptible variety as a disease spreader was used. While under low inoculum level, an aphid resistant variety instead of the infector row was used to control the aphids. Aphid resistance was studied under field and glasshouse conditions. Plants were planted in rows and at 14 DAS, 2 aphids were place on each plant. Aphid resistance was determined by observing the increase in number of the aphid population on the test plants. Gene action governing inheritance of resistance to GRD was studied under high disease pressure created by using viruliferous aphids. Parents and F2 generations and their reciprocals were used in the study. The trials were laid out in a glasshouse and aphids were infested a week after germination and were killed after 7 days using Dimethoate. Disease data was collected at 7, 14, 21 and 28 days after aphid infestation. The study on groundnut cropping systems, varietal preferences and production challenges revealed that most farmers grew groundnut alongside maize (Zea mayis L.) and beans (Phaseolus vulgaris L.) as food crops and tobacco (Nicotiana tabacum L.) and cotton (Gossypium hirsutum L.) as cash crops. The most preferred groundnut varieties grown by farmers were Chalimbana and CG 7. GRD was observed in half of the fields visited. However, 98% of the farmers interviwed had experienced it in their fields at some point, and 63.3% of the farmers believed that GRD was a major problem. Other challenges noted by farmers included lack of quality seed, poor extension support, lack of inputs, manipulation of the markets by buyers, and the failure of groundnut crops to meet the high standards required by the market. The examination of genetic diversity among 106 groundnut genotypes revealed a total number of 316 alleles with a mean of 17 alleles per locus. Polymorphic information content (PIC) and gene diversity values were high, which indicated that genetic diversity among the groundnut genotypes was high. The analysis of molecular variance indicated that 72.9% of the genetic variation observed in the genotypes was due to the variation between individuals within rather than between specific population groups. The evaluation of genotypes for resistance to GRD revealed five highly resistant genotypes namely ICG 9449, ICG 14705, ICGV-SM 05701, MW 2672 and MW 2694. Farmer preferred genotypes were rated as either moderately resistant or susceptible to GRD. Aphid resistance was only recorded in ICG 12991. Yield and GRD incidence were negatively and moderately correlated, which confirmed that GRD has the potential to reduce yield in groundnuts. The highly resistant genotypes were also high yielding except for genotype ICG 9449. Farmer preferred genotypes CG 7, Chalimbana and Tchayilosi, also gave above average yields, despite high disease incidence levels, which showed that these genotypes have tolerance to GRD. The study on gene action governing GRD resistance revealed information on combining ability effects of GRD resistance. The diallel analysis showed that GCA, SCA, reciprocal, maternal and non-maternal effects were all significant, which indicated that both additive and non-additive gene effects played a role in governing GRD resistance. The significance of SCA and reciprocal effects indicated that maternal parents played an important role in the expression of GRD resistance. However, the additive effects were predominant over non-additive gene effects. Four of the resistant genotypes, ICG 14705, MW 2694, ICGV-SM 05701, and MW 2672, were the best combiners for GRD resistance. Generally, the study indicates that there is still a need to develop new varieties with resistance to GRD having traits preferred by farmers to enhance adoption. There is also a need for breeders to work with extension staff in promoting new varieties and also there is need for extension staff to actively provide information to farmers on production and marketing of groundnut. Groundnut is widely known to have a narrow genetic base which has been a bottleneck to its improvement. However, the high genetic diversity observed in this study provides a basis for selection of appropriate parental genotypes for breeding programmes which can enhance further the broadening of the groundnut genetic base. Identification of the genotypes with high resistance to GRD in this study provides an opportunity to breed more GRD resistant materials. The observation that additive gene effects are predominant in governing GRD resistance means that GRD resistant materials can be improved by introgressing additive genes using recurrent selection breeding procedures. There is also a need to employ molecular techniques which can help in shortening the entire breeding process. / Thesis (Ph.D.)-University of KwaZulu-Natal, Pietermaritzburg, 2013.

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Thesis (Ph. D.)--University of Florida, 2009. / Title from title page of source document. Document formatted into pages; contains 507 pages. Includes vita. Includes bibliographical references.

Dissertation (Ph.D.)--Auburn University, 2009. / Abstract. Vita. Includes bibliographic references (p.142-151).

Thesis(M.S.)--Auburn University, 2005. / Abstract. Vita. Includes bibliographic references.

Thesis (Ph.D.) - University of Queensland, 2006. / Includes bibliography.

The passage of the 2002 Farm Bill and the removal of the peanut quota system revealed underlying fundamental problems in the Virginia peanut industry. Lower yields and high costs plague producers at the farm level, acreage levels continue to decline and it is doubtful that peanut production in Virginia will continue at levels seen in the past. The structured market due to the quota system has provided little incentive in the past for technological investment. Investment in technology such as high oleic peanuts and capturing value at the consumer level are seen as ways to improve the situation in Virginia. In particular increased coordination at all levels of the supply chain would be needed to ensure that the consumer is brought a product with characteristics they desire. The literature provides ample information regarding the formation of alliances and coordination in general. According to Cozzarin and Barry (1998), vertical integration, similar to vertical alliances are set up for the following reasons: mitigating transactions costs, taking advantage of output or input price differentials of a competitor, and reducing uncertainties in costs and/or prices. Cozzarin and Barry (1998) also note that there is an increasing move toward vertical coordination in many agriculture sectors, the reasons cited for the current trend include: a) the growing influence of consumers in controlling the agri-food agenda; b) the increasing marketing power of large food companies; and (c) technological changes that necessitate coordination. Of these three reasons, the peanut industry falls under the first two. Vertical coordination is seen to be a solution when two or more entities are able to accomplish more efficiently their objectives than they are able to on their own. For the peanut industry, the agency theory and in particular principal-agent theory is the most applicable to the peanut industry. A linear model is used to examine the effects of increased coordination along the supply chain. The linear model also provides a snapshot of how decisions made at the farm level reverberate through the entire supply chain. The linear model includes the comparison of increased profits due to premiums at the consumer level. Results of the linear model indicate that the Virginia peanut industry will have difficulty maintaining current production levels without investment in the sector, without changing the way the supply chain operates. Principal-agent theory and specifically the work done on contracts in the pork and poultry industries provide a framework within which the peanut industry could avoid asymmetric information and moral hazard. This study attempts to identify underlying problems along with possible solutions or the Virginia peanut industry. / Master of Science

The annual national production of peanut hulls averages about two hundred million pounds. These hulls are generally disposed of as fuel in the plante processing the nuts or discarded as waste material. Similar cellulosic wastes have been profitably utilized in the past as activated ohars. It was the purpose of this work to determine the conditions by which peanut hulls could be converted to liquid adsorbent chars. / Master of Science

To determine the energy saving potential available from recirculating air in peanut drying, a thin layer drying simulation model was adapted to incorporate recirculation. A heat and mass balance computer model was developed to enable the determination of heat energy input. Laboratory crop dryers were designed and constructed to conduct experiments to verify the simulation models. Five batches of peanuts were dried using different recirculation strategies and the model successfully predicted the experimental results, including moisture content and wet and dry bulb temperatures. Energy savings of up to 20 percent were realized in the experimental runs. The simulation model was also used to evaluate and compare several recirculation strategies in order to determine successful strategies. / Master of Science