Cotton Seed Priming with Brassinosteroid Promotes Germination and Seedling Growth

Cotton (Gossypium hirsutum) is the largest fibre crop globally and an important oilseed crop. Rising temperatures and declining water supplies, which are also impacting soil salinity, threaten cotton plant productivity. Germination, emergence and young seedling stages in cotton are highly sensitive to salinity and heat stresses. Brassinosteroids (BRs) are plant steroid hormones that are essential for proper plant growth and development and also promote tolerance to a range of environmental stresses. Cotton seeds were primed with BR (24-epibrassinolide) alone or in combination with other hormones (abscisic acid, auxin and gibberellic acid) and tested for germination and early seedling growth. BR promoted germination under no stress as well as under salinity and heat stress conditions, while other hormones were ineffective under stress conditions. BR also promoted cotyledon opening and the development of lateral roots in germinated seedlings. The ability of BR to positively impact seedling growth across different stress conditions suggests that priming cotton seeds with BR may help in early and successful establishment of seedlings, which may benefit the plant through its lifecycle.