1. Introduction
Haricot is the common name of some food legume cultivated and consumed crops in Africa and Côte d’Ivoire in particular. Among them are the Lima beans, whose major production comes from landraces cultivated in traditional farming system. The seeds are consumed in various forms (pulp, paste and alimentarius complement).
So, despite the importance of bean in the eating habits of certain peoples, the cropping system is still not developed and sustainable, mainly due to the crops’ natural characteristics and current human practices. On the other hand, nowadays in reason of search of benefits, most peasants have opted for industrial crops. Local food crops continue to be neglected.
Yet overcoming food and nutritional insecurity with the ever-growing population size remains a real challenge for African countries, mainly in sub-Saharan Africa. The continent abounds in a rich agricultural and nutritional diversity that can significantly contribute to the reduction of the poverty and the hunger in this region of the world. In this context, an approach based on enhancement of local plants becomes necessary absolutely.
Unfortunately, knowledge of local resource of some of these plants is critically short in plant breeders capable to develop cultivars and stimulate seed systems that meet communities’ needs in the face of climate change. In addition, connecting agriculture, food processing and nutrition can be a sustainable and resilient approach to solving nutritional insecurity problems while helping to improve farmers’ livelihoods. Plant genetic resources are the basis of food security. They serve as a raw material for plant breeding [1] and it is therefore essential that these resources are properly preserved, characterized and evaluated for current and future uses [2].
The conservation and characterization of indigenous genetic resources are necessary to fulfill the needs of breeders. Both aspects are decisive or critical, especially in the success to initiate a plant breeding program [3] [4] [5]. The diversity of different landrace collections, the evaluation of phenotypic variation are still crucial for determining the adaptation and agronomic potential as well as the breeding and nutritional values [6].
The objectives of this study are to identify, document, collect information on the bean. The phenotypic diversity of a set of Lima bean landraces from south of Côte d’Ivoire in the context of traditional farming systems was evaluated. To achieve this objective, prospect and collect were realized in different regions of Côte d’Ivoire. Systematic collection of seeds of bean landraces has been realized. The landrace concept is useful for naming or distinguishing among cultivated varieties through simple traits that are locally adapted to traditional farming systems.
2. Material and Method
2.1. Plant Materials, Sampling Strategy and Collection
Plant material used in this study was constituted to seeds of Lima bean cultivated in areas prospected based on peasant’s knowledge. Sampling strategy has followed hierarchical approach top-down. We designed a survey sheet. The investigations realized in Côte d’Ivoire have started on the greatest markets in Abidjan to select the regions of origin of the seeds sold. When regions have been selected, we determined cities where production of Lima bean is regular. For each city, villages where the crop is cultivated were selected. In each village seeds were collected in field or stock of producer. Investigations were carried out in seventeen localities of Côte d’Ivoire from November 2018 to September 2020. In each zone, a participatory method was used to gather local community knowledge of traditionally cultivated lima beans. The selection criteria were mainly a color and shape of seeds. A systematic collection was carried out. Samples collected in field or stock of producer constitute an “accession”.
2.2. Phenotypic Evaluation and Data Collected
The phenotypic and genetic diversity of Lima bean landraces were typically evaluated through morphological traits: grain color and grain size. Seed characteristics were observed on mature seeds. Different measures were carried out, seed length (30 seeds chosen at random per morphotype) seed width (30 seeds chosen at random per morphotype) and 100-Seed weight (three lots of 100 seeds per morphotype).
2.3. Data Analysis
The data obtained have been subject of descriptive analysis. They’re used here to describe the basic features of the data of each sample. They provide simple summaries about the morphological type. They help us to simplify large amounts of data. To evaluate differences among the morphological types Analysis of Variance (ANOVA) basing of the three parameters was carried out. When significant differences were observed a post ANOVA test Newman-Keuls based on smallest significant differences was carried out.
3. Results
Phenotypic diversity of Lima bean collected, number and distribution
A total of 433 accessions were collected from seventeen localities of south zone of Côte d’Ivoire. Accession is a sample collected in a field or seeds stock of one peasant. The accessions numbers collected in each locality are presented in Table 1. Basing on seed coat color, nineteen morphological types were identified. Among them, six with single color: white, light brown, light red, dark red, black and beige. For thirteen morphological types, seeds are bicolor with very varied patterns (Table 2). The length of seeds is ranged from 10 mm to 23 mm. The width of seeds varies between 7 mm and 15 mm. The 100-Seeds-weight are ranged from 31 g to 120 g (Table 3).
Morphological variation
Comparison of seeds length, seeds width and 100-seeds weight using analysis of variance (ANOVA) showed a significant difference between the nineteen morphological types of Lima bean (Table 3). Two major groups were observed. The first is composed of seven morphological types. The seed length is between
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Table 1. Accessions of lima bean collected during 2018-2020 in Côte d’Ivoire.
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Table 2. Lima bean morphological type cultivated in Côte d’Ivoire.
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Table 3. Values of three traits analyzed according to morphological type of Lima bean and results of statistical tests.
*Means within a column followed by different superscripts were significantly different (P ≤ 0.01), based on Newman-Keuls.
11 mm and 17 mm. Seed width between 7 mm and 12 mm and 100-seeds weight varied from 29 g to 58 g (BLU; DGM; RDG; GrD; WBD; WBL; BEU). The second group is constituted of twelve morphological types (UWnC; ULB; ULR; UDR; UWC; GSB; WSD; DRG; BSG; BUN; DBB; DBO). The seed length varied between 18 mm and 23 mm. The seeds width of this group is between 7 mm and 12 mm and 100-seed weight varied from 105 g to 137 g.
4. Discussion
The evaluation of quantitative and qualitative traits guide to the choice of the breeder on the most adapted morphological type in future breeding activities or to conserve and use them for typical production with high quality. The color, shape and size of seeds are of special attention for consumers. This parameter has often been used by several authors to distinguish different genotypes of cultivated plants [7] [8] [9]. Landraces are indispensable gene stores for developing new cultivar. Our study showed morphological heterogeneity within the Lima bean cultivated in Côte d’Ivoire. A large variety of seeds color was observed between studied landraces. The results of this study suggest that the Lima beans cultivated in Côte d’Ivoire could have a very broad genetic basis. Diverse accessions of them in terms of seed size and seed weight from the Southern of Côte d’Ivoire indicate that this region could be a center of diversity. Diversity of Lima bean based on seed color has been reported by [10]. These observations suggested that preference of people for different seed colors might have played a vital role in the distribution of these accessions. Color of seed could use to classify lima beans landraces cultivated in Côte d’Ivoire. However, analysis of the additional parameters is required before a definitive conclusion. Agronomic characterization and molecular analysis could help to elucidate this hypothesis and highlight the genetic potential of the resource. Based on length and width of seeds, accessions collected could be grouped into two cultivars: large seeds cultivar and small seeds cultivar. This criterion has been used to classify morphological types of oleaginous cucurbit by [6].
5. Conclusion
This study is a review of genetic resources of Lima bean in Côte d’Ivoire. It highlighted nineteen distinct colors of seeds of Lima bean cultivated on small scale in Côte d’Ivoire. Their seeds represent great importance in the sociocultural live of several people. The diversity of color indicates a high genetic variability of the resource. Data collected constitute a preliminary step of our program of valuation of this species. The future study of genetic characterization would help us to appreciate the diversity of Lima bean in Côte d’Ivoire in the objective to carry out sustainable management of the resource.