**Abstract**

In Burkina Faso, three types of sorghum are mainly grown. Despite their genetic proximity revealed by molecular markers, the identification of distinctive agromorphological traits between sweet grain sorghum, sweet sorghum and grain sorghum could contribute to better management of their genetic resources. Thus, 42 genotypes consisting of the three sorghum types were evaluated in a three replicate Fisher incomplete block design using 20 quantitative traits. The results showed a high variability of traits within each sorghum type and a greater closeness between sweet grain sorghum and sweet stalk sorghum. In addition, nine traits clearly discriminated sweet grain sorghum from the other sorghum types. Sweet grain sorghum expressed the highest values of the sowing-heading cycle, leaf sheath length, stem diameter, productive tillers, and panicle width and the lowest values of mean heading-flowering difference, 100-grain weight, and Brix. Moreover, the 'sorghum type' factor is less preponderant than the 'genotype factor' in expressing the variability of all traits. Therefore, the 42 genotypes are organized into three genetic groups independently of the sorghum- type factor, where the group I contains all sweet grain sorghum genotypes and three sweet stalk sorghum genotypes. These results could be exploited in sorghum breeding programs.

**Keywords:** sorghum, agro-morphological variability, genetic relationship, Brix, Burkina Faso

### **1. Introduction**

Burkina Faso is a Sahelian country whose socioeconomic development is mainly based on agriculture [1]. The agricultural sector employs about 80% of the total population and is the country's main provider of food resources [2]. However, agricultural production is affected by climatic hazards such as irregular rainfall and shortened rainy seasons, resulting in huge yield losses and permanent food insecurity [3]. To cope with these climatic constraints, crop diversification appears to be the most appropriate solution for resilient agriculture.

In Sahelian countries such as Niger, Mali, Senegal, and Burkina Faso, cereals are the staple food of the population [4]. Sorghum [*Sorghum bicolor* (L.) Moench] is the most important crop. Moreover, it is the main food crop for millions of people and excellent fodder for animals in semiarid and arid tropical areas [5]. Sorghum is the fifth most important cereal crop in the world and the third most important in Africa after maize and rice in terms of production volume and area sown [6].

In Burkina Faso, sorghum is the second most important cereal crop after maize, with an estimated total production of 1,839,570 tonnes, including 1,425,103 tonnes of white sorghum and 414,467 tonnes of red sorghum [7]. However, these statistics do not highlight all types of sorghum produced. Indeed, several types of sorghum with varied but little known potential are grown in Burkina Faso and maintained by farmers [8–10]. These include grain sorghum, sweet grain sorghum, sweet sorghum, and dyer sorghum [11]. These sorghums are mainly exploited for human consumption for their grains or the sweet juice from their stems, for animal feed for their straw, and for dyeing for their strongly anthocyanated leaf sheaths [11]. The dynamic management of this diversity by farmers allows for evolutionary adjustment to a heterogeneous environment, but also to meet diversified use needs [12]. Most previous studies focusing on genetic diversity within each sorghum type have reported the existence of genetic diversity within grain sorghum [12–14], sweet grain sorghum [10], and sweet sorghum [11]. In addition, grain sorghum and sweet sorghum have been the subject of several scientific works. However, work on sweet grain sorghum is relatively recent [9, 10, 15, 16]. Therefore, information on the distinctive agro-morphological traits of this sorghum compared with other cultivated sorghums remains scarce. This could constitute a constraint to the rational exploitation of the potential of this genetic resource in breeding programs. To date, few studies on the genetic relationships between sweet grain sorghum and other sorghum types grown in Burkina Faso have been carried out using nuclear and chloroplast molecular markers. Although the results obtained showed genetic proximity between these sorghum types [17, 18], the evaluation of these sorghums under identical cropping conditions could help identify agro-morphological and biochemical traits specific to sweet grain sorghum that could be exploited in sorghum improvement programs. Thus, the present study aims to compare the quantitative agro-morphological and biochemical characteristics of sweet grain sorghum with grain sorghum and sweet sorghum grown in Burkina Faso. In particular, the aim is to (i) determine the agro-morphological and biochemical traits of sweet grain sorghum that are similar to those of other cultivated sorghums, (ii) identify the distinctive traits, and (iii) evaluate the effect of the factors "genotype" and "sorghum type" on the variability of the three types of sorghum grown in Burkina Faso.

*Assessment of Genetic Variability of Three Types of Sorghum Cultivated in Burkina Faso... DOI: http://dx.doi.org/10.5772/intechopen.105984*
