Ciclos descontínuos de hidratação aumentam a tolerância ao déficit hídrico em sementes de algodão 'BRS Topázio'

Abstract

The harmful effects caused by water deficit can affect germination and reduce the final yield of the cotton plant, which can be overcome by carrying out discontinuous hydration cycles, which stimulate osmotic tolerance and can improve the response of cotton sensations to this type of stress. To evaluate the germination and initial growth of colored cotton seedlings, cultivar ‘BRS Topázio’, under discontinuous hydration cycles in seeds after eight years of storage. For this, the seeds of “BRS topázio” were subjected to 0 (without hydration), 1, 2 and 3 cycles of hydration (10 h) and dehydration (18 h), with subsequent germination under simulated water stress for osmotic potentials 0 , 0 (distilled water); -0.3; -0.6 and -0.9 MPa. The evaluations evaluated were: Germination (%); Germination Speed Index (IVG); Average Germination Time (AMR); Aerial Part Dry Mass (MSPA) Root Dry Mass (MSR) and Total Dry Mass (MST) of seedlings and roots (g plant -1). The use of three discontinuous hydration cycles was more favorable to germination (21 and 40%) under severe water stress (-0.9 and -0.6 MPa), respectively. In colored cotton seeds, cultivar “BRS topázio”, the application of three cycles of hydration and dehydration for a period of 10h and 18h respectively, increases tolerance to severe simulated water stress (-0.9 MPa) during germination and development of seedlings, when compared to the control treatment. The hydration curve described by the three-phase model appears in phases I, II and III of germination, for periods of 13, 22 and 24 hours. While the dehydration curve to return to initial weight lasts 22 hours.