Overcoming dormancy of achenes and physiology of strawberry treated with plant regulators

Hybridization is one of the most efficient ways to explore the genetic variability of the strawberry. However, germination of strawberry achenes is a complex activity, often associated with very low germination percentage. One of the ways to overcome dormancy is the use of plant regulators. The aim of this trial was to verify the effect of plant bioregulators on the germination of achenes and also the physiological aspects on the growth and development of strawberry seedlings obtained from achenes. The achenes of 'Albion' strawberry were scarified in sulfuric acid (H₂SO₄ 98% v/v) for 40 min, the time of soaking in water was determined with the following treatments then applied: indole-3 butyric acid (IBA), gibberellic acid (GA₃), 6-benzylaminopurine (BAP) and commercial plant regulator Stimulate^® in concentrations of 0, 25, 50 and 100 mg L^‑1. The average time and the percentage of achene germination were evaluated. Additionally, at 40 d after germination, strawberry seedlings were sprayed with treatments containing IBA, GA₃, BAP, Stimulate^® and control (H₂O) and evaluated for net carbon assimilation, internal CO₂ concentration, stomatal conductance, crown diameter and area leaf of seedlings. Strawberry achenes reached maximum imbibition after 4 h. All treatments provided a constant increase in the germination percentage until 35 d after sowing. Stimulate^® and AIB in concentrations of 100 mg L^‑1 promoted the highest germination of strawberry achenes scarified with sulfuric acid and an estimated concentration of 63 mg L^‑1 of Stimulate^® provided the greatest initial development of seedlings. The plant regulators did not increase the gas exchange rates of strawberry seedlings in relation to the control treatment. Stimulate^® together with BAP also improved the development of strawberry seedlings, with an increase in crown diameter and leaf area.