**10. Concluding remarks and future breeding perspectives**

The three classes of genes (*Vrn*, *Ppd*, and *eps*) play a vital role in the adaptation and protec‐ tive mechanisms to ensure successful reproduction of wheat in diverse environments around the world. It has been revealed that a combination of *Vrn‐*1 (especially *Vrn‐A*1) and *Ppd‐D1a*

results in genotypes that are early flowering under both SD and LD conditions, but flowering time is delayed under SD conditions. Moreover, a significant correlation between flowering time and plant height has been reported suggesting the possibility of genes regulating flow‐ ering time to also regulate height [5, 80]. Therefore, semidwarf genotypes are said to flower earlier (and may give higher yield) as compared to taller or normal ones depending on the environment and the genotype by environment interactions.

In the view of the current and projected climate change, which will include extreme hot and dry conditions**,** selecting for *Rht*8 genotypes could be beneficial relative to the *Rht‐B1b* and *Rht‐D1b* genotypes, which only perform well under high input conditions. In contrast, *Rht*8 genotypes have been shown to perform well and give higher yields under hot and dry environments. Climate change necessitates that the genetic structure of current breeding programs be shaped accordingly. Therefore, breeding for wheat cultivars with flexible response in different envi‐ ronments and that exhibit superior performance under extreme conditions, such as hot and dry environments, should become a priority. Photoperiod insensitivity is usually an advantage in most regions [100]. Therefore, selecting for the trait and incorporating genes for other comple‐ mentary traits, such as preharvest sprouting resistance into the advanced lines, could be an added advantage in addition to significant yield improvement. Selecting for favorable alleles in targeted environments will contribute to yield improvement in the wheat production industry. This will help to meet the ever‐increasing demand, which will mean sustainable food security.

Selection of favorable alleles could increase the level of variation and/or introduce novel sources of resistance to diseases and unfavorable weather conditions into breeding populations [9, 26, 95, 101]. This allows the transfer of genotypes between regions with different climatic condi‐ tions but still maintains their level of agronomic performance [5]. The *Ppd‐D1a* allele has been selected for by plant breeders in different countries for several decades to enhance yield in cer‐ tain climatic conditions [10, 46, 100]. Selecting for favorable alleles also allows the development of allele‐specific DNA markers for efficient detection of extensive allelic variation among genes controlling traits of agronomic importance [35, 46, 95]. As a result, the genetic components of flowering time and other traits of agronomic importance are now better understood and some of the associated genes are isolated and cloned in wheat and closely related species [15–17, 46, 101]. The information provided in this chapter will therefore be helpful in the current and future breeding programs when breeding for adaptation and improved yield in wheat.
