1. Introduction

Okra (Abelmoschus esculentus (L.) Moench) is an annual fruit vegetable crop propagated through seed and commonly grown commercially in tropical and sub-tropical regions of the world. It is also grown in warmer temperate regions of the Mediterranean region [1]. Currently, this crop is found all over the African continent [2–5]. It is one of the most important

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© The Author(s). Licensee InTech. 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 eproduction in any medium, provided the original work is properly cited.

African indigenous fruit vegetable crops belonging to the family Malvaceae. It originated in Ethiopia [6], the former Abyssinia, and was cultivated by the ancient Egyptians. Its cultivation spread throughout Middle East and North Africa [7, 8]. In Ethiopia it is also called Kenkase (Berta), Andeha (Gumuz), and Bamia (Oromica/Amharic) [9]. Authors of Refs. [4, 9–11] reported that okra is a multipurpose crop due to its various uses of the pods, fresh leaves, buds, flowers, stems, and seeds. The immature fruits can be consumed as vegetables, in the form of salads, soups and stews, fresh or dried, fried or boiled. The plant contains mucilage in various plant parts, which is associated with other important substances including tannins [12]. The biological functions of mucilage within the plant includes aiding in water storage, decrease diffusion in plants, aid in seed dispersal and germination, and act as a membrane thickener and food reserve. Okra contains proteins, carbohydrates, and vitamins [8] that plays a substantial role in food security, human health [5], and nutritional security. Consumption of young and green immature okra fruits is very important as fresh fruits, and it can be consumed in different forms [13] such as boiled, fried, or cooked. Okra seeds contain about 20% protein and 20% oil [7]. It was reported that the seeds can be dried and the dried seeds are a nutritious material that can be used to prepare vegetable curds or roasted and ground to be used as coffee additive or substitute [14]. Moreover, okra leaves can also be used as animal feed. In similar fashion, the green leaf buds and flowers are also edible [15]. Okra mucilage is used for industrial and medicinal applications [16] in different parts of the country in the world. Industrial use of mucilage is usually for glace paper production and has a confectionery use. Okra has found medical application as a plasma replacement or blood volume expander [17, 18]. A study conducted in China suggested that an alcohol extract of okra leaves can eliminate oxygen free radicals, alleviate renal tubular-interstitial diseases, reduce proteinuria, and improve renal function [19].

the variation in the agro-morphological and nutritional composition of okra has not been determined in the country. Therefore, it is important to profile okra genotypes using agromorphological traits and nutritional contents in the immature fruits of okra for future breeding

For field evaluation, 50 genotypes of okra (Table 1) were obtained from the AVRDC (World Vegetable Center), Taiwan. In this study, the field experiment was conducted in the Gauteng province of South Africa under rain-fed conditions during the 2015 and 2016 summer growing

situated at an altitude of 1168 m above sea level. Roodeplaat has annual maximum average temperature ranged from 15.38 to 30.36�C and receives an average annual rainfall of 584.21 mm during the cropping seasons. The experimental site has loam clay type of soil. Two seeds of each okra genotype was planted in three rows of 4 m length spaced at 0.85 m between rows and 0.4 m between the plants. The seedlings were thinned into one when fully establishment in the field. A randomized complete block design with three replications was applied. Trial management such as plot preparation, and hand weeding were done when required and supplementary irrigation was employed when rainfall is not enough for the growth and development of the crop under

Morphological phenotypic traits were evaluated and recorded using the International Plant Genetic Resources [23] okra descriptor list. The agro-morphological traits record includes plant height (PH), number of fruits per plant (NFP), number of branches per plant (NB), number of leaves per plant (NL), number of internodes (NI), internode length (IL), stem diameter (SD), leaf length (LL), leaf width (LW), days to 50% flowering (D50%F), fruit length (FL), fruit diameter (FD), fresh fruit yield (FYLD), number of seeds per fruit (NSF), 1000 seed weight (TSwt), shell weight (Swt), fruit harvest index (FHI) and grain yield per plant (GY) (Table 1).

The fresh and immature fruits of the okra genotypes were harvested and analyzed for total protein content and selected mineral elements (calcium, copper, iron, potassium, magnesium, manganese, sodium, phosphorus, aluminum, boron and zinc) at the analytical laboratory of the Agricultural Research Council in Pretoria, South Africa. Fruits of okra were collected from each replicate in the field for analysis of mineral elements and protein content. Laboratory analysis were performed in triplicate and the results were expressed as mean for analysis

Protein analysis: A dry oxidation method was used to determine the total nitrogen and the

E) research farm of the Agricultural Research Council. It is

Agronomic Performance, Nutritional Phenotyping and Trait Associations of Okra…

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2. Agronomic performance and nutritional quality of okra

S; 28�35<sup>0</sup>

purposes in South Africa.

seasons at Roodeplaat (25�59<sup>0</sup>

2.1. Agronomic characterization

2.2. Nutritional characterization

crude protein contents (N � 6.25) of the samples [24, 25].

research.

(Table 2).

Okra is a traditional crop, which requires relatively low agronomic input, but can contribute substantially to sustainable agricultural production and productivity in South Africa and beyond. This species is under-exploited and have potential for contributing toward food, nutritional, and health security for current alarmingly growing population, contributes a vital role in income generation and poverty alleviation. It is a valuable source of nutrients [20] with important medicinal properties [21]. Its wide range of biodiversity contributes to food, nutritional security, health benefit, and income diversification in the subsistence farming system that predominates in the different parts of the world. Therefore, improving the genetic potential of indigenous fruit vegetables like okra species is of paramount importance for yield, and nutritional quality. Evaluation and characterization of germplasm is important and the first step to the breeders who desire sources of genes for novel traits. It was reported that characterization of genetic resources refers to the process by which accessions are identified, differentiated, or distinguished according to their morphological and/or nutritional quality traits [22]. Currently, there is no clear record on genetic characterization and evaluation of the genetic resources of this crop under South African condition. Okra production and productivity is negatively due to the use of low yielding local landraces and use of poor agronomic management practices. Furthermore, production technology, development of new cultivar, and okra management practices are very limited in South Africa. To date, there are no reports of any improved cultivars developed in South Africa for high yield, nutritional contents as well as disease and pest tolerance. In addition,

the variation in the agro-morphological and nutritional composition of okra has not been determined in the country. Therefore, it is important to profile okra genotypes using agromorphological traits and nutritional contents in the immature fruits of okra for future breeding purposes in South Africa.
