**4. Aspects linked to artificial hybridization**

Adequate selection methods used in breeding programs of a species can reduce time and investment and maintenance of evaluating plants that could be previously discarded [65]. Thus, selection strategies linked to genetic, biochemical, physiological, nutritional, and agronomic characteristics can help due to the high detection efficiency and low cost [66]. In addition, the knowledge of the genetic control related to these characteristics will establish breeding strategies and selection of agronomically superior plants, with genes of tolerance to

The aims of this chapter are to (i) present the importance of the cowpea crop, (ii) demonstrate problems related to drought, (iii) describe aspects related to flower structure and hybridiza‐ tion, and (iv) reveal how the genotype selection with tolerance to water deficit will promote

In relation to flowers, the cowpea bean flower is hermaphrodite, deciduous, cyclic, dichla‐ mydeous, and heterochlamydeous with zygomorphic symmetry (Figure 1). The five sepals and petals present are in free condition, denominated polysepalous and polypetalous,

**Figure 1.** *V. unguiculata* floral pieces*. (*A) standard; (B) post-anthesis flower structure; (C) sepals; (D) stamen and pistil;

drought.

**2. Objectives**

respectively [67].

increase of the yield in this culture.

568 Abiotic and Biotic Stress in Plants - Recent Advances and Future Perspectives

**3. Flower structure in cowpea**

(E) longer stamen; (F) keel formation [67].

The results described by Ribeiro et al. on aspects of the floral biology of *Vigna unguiculata* reveals that anthesis occurred between 05:00 and 05:30 h [67]. In pre-anthesis, at 4:00 h, the greenish flowers remained. In the stigma receptivity test, peroxidase action was observed at all times. As noted by Rocha et al., the floral opening of cowpea bean flowers begins around 05:30 h and continues until 09:30 h, when the stigma is still receptive (Figure 2) [68].

**Figure 2.** Peroxidase activity on *V. unguiculata* stigma, demonstrating receptiveness [67].
