Determination of resistance mechanisms to water deficit induced during the flowering stage in twelve varieties of cotton (Gossypium hirsutum L.) in Togo.

Abstract Background: One of the limiting factors of cotton production in West Africa and more particularly in Togo is drought. Identifying the resistant varieties and understanding the mechanisms involved in their resistance is a major asset for the breeder. In this context, twelve (12) varieties of cotton (Gossypium hirsutum) were studied under two water regimes (normal and deficit during flowering), in 30 L plastic pots, under controlled sowing conditions, following a split-plot design with three replications. The induction of water deficit consisted of a decrease in irrigation from 70% to 30% of the total available water (TAW) for thirty (30) days. Observations were made on agromorphological and biochemical characteristics. Result: The results showed that decreased water deficit decreased seed cotton production, aerial and root biomass, vegetative branches bolls, and chlorophyll content. On the other hand, the water deficit increases the average weight of the bolls. The resistant varieties to the water deficit were characterized by an increase in the main root length (X148), the chlorophyll content (STONE 907), the secondary roots number, and proline content (BRS 286), and a decrease in the MDA content (STONE 907). The susceptible varieties were characterized by high MDA content (NTALL88) and a low secondary root number (Deltatpine SL Frego). Conclusion: The varieties STONE 907, BRS286, and X148 can be used as progenitors in crossing programs to improve the water deficit resistance of cotton varieties grown in Togo and West Africa countries.