Do methods for overcoming dormancy affect the physiological quality of okra seeds?

Abstract

ABSTRACT One of the main obstacles in the okra production is the physical dormancy imposed by the tegument of the seeds. Although several methods for overcoming tegumentary dormancy have been proposed, little is known about their effect on the physiological quality of seeds. Thus, this study aimed to verify the effectiveness of methods for overcoming dormancy (control - no treatment; pre-soaking - seed soaking in water at 30 ºC, for 6 h; thermotherapy - immersion in water at 60 ºC, for 3 min; dry heat - oven at 70 ºC, for 5 min; thermal shock - immersion in water at 30 ºC, for 30 min, followed by 5 ºC, for 24 h; and sand scarification - friction between seeds and sand for 20 min), as well as to analyze their impacts on the physiological quality of okra seed lots. After the treatments were applied, images of the outer seed coat were obtained and the moisture content of the seeds, first germination count, germination, emergence, germination speed index and seedling length were measured. The treatments of pre-soaking, thermotherapy and thermal shock remove cell layers in the chalaza region, allowing a greater water absorption and showing to be efficient in overcoming dormancy, without affecting the physiological quality of the seeds. On the other hand, the dry heat treatment can affect the vigor of okra seeds.