Ecophysiological Adaptation of Soybeans to Latitudes Through Photoperiodic and Growth Habit Genes

Photoperiodic genes in soybean affect latitudinal adaptation, plant growth, and overall productivity of the crop. Soybean adapts to large latitudinal zones from 50°N to 40°S, but its individual accessions adapt to a very narrow latitudinal band. For its worldwide production, major considerations are its photoperiodic and growth habit genes. Inheritance of the photoperiodic genes and role of these genes regulate early or late flowering and also regulate early or late maturity of the crop. In this chapter, we have summarized the photoperiodic and growth habit genes and their role in soybean flowering and maturity. We have also discussed their mapping, mechanism, quantitative trait loci (QTL) study, and linked markers. Major photoperiodic genes include E1 gene, E2 gene, E3 gene, E4 gene, E5 gene, E7 gene, E8 gene, and E10 gene, and genes responsible for growth habit, Dt1 and Dt2, interact with each other and are involved in the functions of flowering, maturity, and plant architecture. Specific combinations of these genes have been found to confer adaptation to specific zones of the world. Therefore, such study will be useful in the development of varieties adapted in adverse conditions of photoperiod in different zones of the country. Plant photoperiodic response provides the synchronization of their growth pattern with the seasonal events and, therefore, their better adaptation. At the same time, high photoperiodic sensitivity can retard the dispersal of important agricultural crops. These problems are solved with various breeding strategies.