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Characterization and evaluation add value to the collected and introduced germplasm; also increase its utilization in crop improvement. Germplasms are the most valuable and essential raw materials in meeting the current and future needs of crop improvement programs. Sweet potato has a very high genetic variability and thousands of accessions of sweet potato exist in germplasm collections at the International Center for Sweet potato. More than 8,000 accessions, cultivars and breeding lines of sweet potato (2n = 6 — = 90), and nearly 26,000 accessions of other Ipomoea species are maintained in 83 gene banks world-wide (Kuo, 1991, Rao et al.
, 1994). The characterization of germplasm diversity and the genetic relationships among cultivars, genotypes and breeding lines are critical in crop improvement programs.Characterization and evaluation of plant genetic resources are performed by using morphological descriptions of vegetative and reproductive organs in addition to classical agronomic assessment (Lowe et al., 1996). In previous studies, Tairo et al. (2008) characterized 136 sweet potato land races collected from three different agro-ecological zones of Tanzania, and (Yada et al.
, 2010) used 40 morphological descriptors in characterization of 1,303 accessions collected from 21 districts in Uganda. (Improvement work in sweet potato can be limited by a lack of knowledge of available genetic diversity (Tairo et al., 2008). Therefore, comprehensive information concerning locally available sweet potato germplasm is of vital importance for the advancement of current cultivars.In Guyana, extensive work has been done on characterization of sweet potato during the 1990s; however, the major sweet potato germplasm has been lost at the main agriculture research institute. Information available in the sweet potato base does not make identification of local accessions simple with the lack of photographs for most of the accessions.
Sweet potato is very frequently associated with small farmers who are responsible for maintenance of many genetic diversity of the crop in on farm conservation. The modernizations of agriculture and rural exodus have caused loss of genetic diversity in crops, including the sweet potato. Therefore, it is essential to collect and to conserve germplasm and keep it in organized collections for later characterization, evaluation and documentation (Cabral et al., 2010).F. DETAILED PROPOSAL OF RESEARCH PROJECTBackgroundSweet potato (Ipomoea batatas (L.) Lam.), belonging to the family Convolvulaceae, is grown in more than 100 countries in tropical, subtropical and temperate climates (Woolfe, 1992). It is a major staple food in Africa, Asia, the Caribbean and South America, where it is an important source of carbohydrates, vitamins A and C, fiber, iron, potassium and protein (Woolfe, 1992). It ranks as the world’s seventh most important crop, with an estimated annual production of approximately 110 million metric tons (FAOSTAT, 2008).The traditional farmers play an important role in plant genetic resources conservation. Collecting the germplasm maintained by these farmers is a very important action to avoid genetic variability losses. Similarly, this project was conducted in Brazil where the goals of the project were to collect sweet potato from farms in the north of Rio de Janeiro state; to gather information regarding the farmers’ profile, and to characterize the sweet potato landraces collected using morphological descriptors. Fifty three farms were visited in six collection expedition and 46 accessions were collected. During the visits the farmers were interviewed using a query with ten items. Six root traits and eight descriptors for vegetative parts were used for morphological characterization. The morphological characterization was efficient to detect genetic variability among accessions, revealing that traditional farmers from Campos dos Goytacazes and SЈo JoЈo da Barra are responsible for sweet potato genotypes conservation with expressive genetic diversity in their properties. Sweet potato is one of the most important root crops in Mozambique and within the scope of the national and regional strategies/initiatives, a multi-analysis approach to characterize the national sweet potato germplasm collection at two different levels: i) genetic, morphological and agronomic diversity; and ii) agronomic potential (storage root yield, vine weight, biomass, harvest index and dry matter content) toward drought tolerance was conducted. The collection comprised of 44 accessions and 28 genotypes cultivated in three different provinces of Mozambique.The increasing recognition of the great potential of sweet potato as a crop for combating malnutrition and food security has resulted in intensified research efforts in recent decades to enhance its production and consumption (Woolfe, 1992, Yamakawa and Yoshimoto, 2002).Morphological characterization activities make available information on the conserved germplasm, placing it in the most effective form for use, and it is important to emphasize that the value of the germplasm increases as it becomes known and documented (Painting et al., 1995; Sudr© et al., 2010).Hypothesis /Problem statment/ JustificationOne of the main characteristics of the sweet potato is its high phenotypic and genotypic variability (Vilas Boas et al., 1999; Veasey et al., 2007) that confers adaptability to different edaphoclimatic conditions. The occurrence of the same cultivar with different names and vice versa is quite common (Daros et al., 2002). This way, collecting sweet potato germplasm in rural properties would implicate in a situation which two different accessions in a gene bank could correspond to the same genotype. Duplicate genotypes in gene banks can be identified by, for example, morphological characterization of the germplasm which is normally the most feasible way to quantify its genetic diversity and has been frequently used (Rabbani et al., 1998; Ritschel et al., 2002). Morphological characterization activities make available information on the conserved germplasm, placing it in the most effective form for use, and it is important to emphasize that the value of the germplasm increases as it becomes known and documented (Painting et al., 1995; Sudr© et al., 2010).Modernizations of agriculture and rural exodus have caused loss of genetic diversity in crops, including the sweet potato, it is therefore importance to maintain the crop genetic variability that exists on small farms . Thus it is essential to collect and to conserve germplasm and keep it in organized collections for later characterization, evaluation and documentation (Cabral et al., 2010). In this way, it will be possible to estimate the real variability maintained to make the conserved germplasm available for effective use by researchers in several areas such as breeders and botanists or even the farmers themselves.Hypothesis H0 ” There is a need for characterization and evaluation of sweet potato germplasm.H1 ” There is no need for characterization and evaluation of sweet potato germplasm.Research objectivesThe objectives of the project are:i) To collect local sweet potato varieties on farms from different regions in Guyana; ii) To gather information regarding the profile of the farmers who traditionally cultivate and maintain sweet potato germplasm;iii) To characterize the accessions collected based on morphological descriptors;iv) To rescue and assess agronomic performance in accessions collected in traditional communities.Rationals/Description of methodologyAccessions will be collected from farmer’s field in the different regions. The collection from the different regions will be done with support from the Agriculture Extension officer within the respective regions. At the time of collection, farmers will answer a questionnaire that will be designed to understand his profile, considering the following items: farmers’ name; collection location; local name for the sweet potato; precedence of the cropped genotypes; end destination for the product; pest and disease incidence in the crop; chemical product application; annual yield and time the farmer had exercised this activity. Stem cuttings and tubers will be collected where possible. Characterization will be done shortly after collection for tubers, considering six root morphological descriptors (shape, surface defects, skin color, skin color intensity, flesh color and secondary flesh color) proposed by Huamn (1991). Stem cuttings will be placed in potting bags and allowed for growth. The characteristics of the vegetative part will assessed approximately three weeks after planting using ICSP descriptors.Project work planProject activities Jan-Feb2018 Mar-Apr2018 May- June 2018 Jul- Aug 2018 Sep- Oct 2018 Nov- Dec2018 Jan- Feb, 2019 Collection of accessions – – – – – Setting of tubers & cuttings – – – – – Planting in field – –Digital photo – – – – – –Number of vines – – Data collection – – – – – – –Maintenance of plants – – – – – – –Statistical analysis – –Scope of studyThe research will contribute to the economy and sustainability of Guyanese agriculture by providing information for sweet potato breeding, for commercial cultivation and to determine the use of the accessions. The descriptors will take into consideration desirable traits to meet the market demands. For sweet potato, these traits are total and commercial productivity, adaptability and stability of accessions in a particular growing region, occurrence of skin defects, and resistance to pests, among others.Producers’ children have no interest in remaining in the countryside and go to the cities to study and/or obtain jobs with better income. This emphasizes the importance of collecting and maintaining this germplasm by public research institutions to preserve the genetic variability of these typical small producer crops.References 1. Horticultura Brasileria, vol.30 no.2 Vitoria da Conquista Abr. /June 2012.2. Isolation, Modification and Characterization of Sweet Potato (Ipomoea batatas L (Lam)) StarchDepartment of food science and technology, Federal University of Technology, Owerri, p.m.b. 1526 owerri, Imo state, Nigeria.3. Marcquin Chibuzo Iheagwara South African Journal of Botany .Volume 88, September 2013, Pages 142-151.
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