1. Introduction

Phaseolus vulgaris L. known as common bean is a member of the family Fabaceae [1]. It is an annual leguminous crop grown for its nutritional leaves, tender pods, and dry seeds [2]. It is a warm season legume crop and is self-pollinating with low frequency of crossing [3]. P. vulgaris provides protein and calories [4] as well as micronutrients such as zinc (Zn) and iron (Fe), essential vitamins, dietary fiber, and fat [5]. It is also an important legume which contains antioxidants [6, 7] and other chemically diverse components which fight against many diseases [8].

A landrace is defined as a crop with wide genetic diversity, which is usually identifiable, is known locally, has a local name, and has not undergone the proper crop improvement [4].

> © The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons © 2018 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and eproduction in any medium, provided the original work is properly cited.

Landraces of P. vulgaris show a wide range of variation in their vegetative and reproductive traits [5]. The germination percentage among common bean cultivars ranges from 89 to 94% [9]. P. vulgaris landraces either show bushy, determinate, or indeterminate climbing growth form [10]. The number of branches among P. vulgaris landraces ranges from 17 to 57, and the number of leaves ranges from 19 to 37 [1]. Furthermore, days to flowering ranges from 26 to 40 days after sowing in P. vulgaris cultivars [9]. Some P. vulgaris landraces show white flower color, while others lilac [10]. P. vulgaris landraces have green and yellow mottling color of immature and matured pods, respectively [11]. Seed colors vary from black, brown, cream, green, mix red and white around the hilum, purple, and white to white/mottled [10, 12]. Pod color varies from pure green to green with purple or carmine stripes [11]. Pod length varies from 67.4 to 163.4 mm [13]. The number of pods per plant among P. vulgaris cultivars ranges from 5.4 to 9.9, while the number of seeds per pod ranges from 2.9 to 4.4 [9]. Seed length also ranges from 10.0 to 16.7 mm, width from 6.1 cm to 9.8 mm, and height from 4.2 to 8.2 mm [14]. Studies on the variation among P. vulgaris landraces are essential to select the desired traits for future breeding.

source of iron and thus is consumed as a meat substitute [7]. In some varieties, green immature pods are cooked as vegetable, while mature seeds are cooked and consumed for their high nutrient content [21]. The consumption of P. vulgaris is higher among both rural and urban

Morpho-Agronomic Variation among *Phaseolus vulgaris* Landraces: A Review

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The consumption of common bean has health benefits by decreasing and preventing the glucose and cholesterol level [21, 22]. It also prevents stress and cancer and decreases heart diseases and obesity [8, 21]. It consists of enzyme inhibitors as well as compounds such as phenolic, phytates, and lectins, which help in metabolic functions in animal and human body

However, P. vulgaris also has some problems due to the presence of certain anti-nutritional compounds such as saponins, flatulence factors, lectins, and phytic acid, and it also needs prolonged cooking [21, 22]. P. vulgaris fixes nitrogen to the soil through rhizobia by nitrogen-

Landraces are crops with wide genetic diversity, which are usually identifiable, are known locally, and have not undergone the proper crop improvement [4]. Landraces are categorized into primary and secondary landraces [24]. Primary landraces contain their original and uncontaminated traits, whereas secondary (improved) landraces consist of foreign material that was incorporated into them through partial breeding [24]. Secondary landrace may change back to primary landrace after sometime [24]. An autochthonous landrace is a variety which is native and grown for a long period of time in a certain environment within a particular agricultural system [25]. It has specialized traits that allow biotic and abiotic stress conditions to increase and stabilize their yield [25]. Allochthonous landraces are varieties which are taken from other regions and introduced (grown) in another region and then allowed to adapt to that new region [24]. Landraces are naturally selected and are also

Landraces play a significant role in agricultural production ensuring quality and wellmanaged crops [26]. They are varieties that have genotypes with wide specific traits [27]. These traits are adaptive to a specific environment and produces well-improved genotype, reduces the vulnerability, resistance to pests and diseases [27]. Landraces serve as a source of genetic diversity, and plant breeders often use specific traits to create new variation and maximize genetic diversity [12]. It also plays important role in ensuring food security [26]. Landraces result in high to intermediated yield, which is also stable under a low-input agricultural system in small-scale farmers [24, 27, 28]. They are a unique source of special traits which have marginal environment tolerance and nutritional quality [26]. The basis of diversity in landraces

Common bean landraces have advantages of adaptation to cultural practices and local climatic conditions, resistance or tolerance to diseases, and early or late seed maturation, resulting high to intermediate yields under low inputs [10]. In eastern and southern Africa, farmers grow P. vulgaris landraces as genetic resources to be used for breeding programs [11]. P. vulgaris

characterized by the lack of formal genetic improvement [26].

societies with low income [20].

systems [6].

fixing bacteria [23].

2.3. Landraces and their uses

is genetic heterogeneity [29].
