Resistance mechanisms of twelve varieties of cotton (gossypium hirsutum l.) to water deficit induced during the flowering stage in Togo

Background: One of the limiting factors of cotton production in West Africa, particularly in Togo, is drought. Identifying the resistant varieties and understanding the mechanisms involved in their resistance is a fundamental asset for the breeder. Objectives: Theaims of this research were to: (i) compare the resistant and susceptible varieties under water deficit conditions on the agro morphological and biochemical levels and (ii) identify the traits responsible for water deficit resistance. Methods: Twelve varieties of cotton (Gossypium hirsutum L.) 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 observations were made on agromorphological and biochemical characteristics. Results: The results showed that water deficit decreased seed cotton production (-23%), aerial biomass (-29%), root biomass (-41%), vegetative branches bolls (-49,56), root volume (-26,34%), and chlorophyll content (-79% to 79%). On the other hand, the water deficit increased the average weight of the bolls (+23%). The resistant varieties to the water deficit were characterized by an increase in the primary root length (variety X148), the chlorophyll concentration (variety STONE 907), the lateral root number, and proline content (variety BRS 286), and a decrease in the MDA content (STONE 907). The susceptible varieties were characterized by high MDA content (variety NTALL88) and a low lateral root number (variety Deltatpine SL Frego). Conclusion: 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 African countries.