Abstract
(1) Background: Seed treatment with potassium nitrate (KNO3) has been associated with dormancy breaking, improved germination and enhanced seedling growth and uniformity in a variety of plant species. However, the KNO3 effect seems to be dependent on plant species and treatment conditions. (2) Methods: We describe the effect of incubation of dry pea seeds with different KNO3 concentration on water uptake kinetic, early seedling growth, antioxidant metabolism and hormone profile in pea seedlings. (3) Results: Low (0.25 mM) KNO3 levels increased seedling water uptake and growth, whereas high (40 mM) levels decreased seedling growth. KNO3 treatment differentially affected the antioxidant defences. Low KNO3 levels maintained the activity of antioxidant enzymes, while high levels reduced the activity of H2O2-scavenging enzymes. KNO3 induced a progressive decline in ascorbate levels and reduced (GSH) and oxidised (GSSG) glutathione. Low KNO3 levels strongly increased GA1 and decreased ABA in both seedlings and cotyledons, resulting in a decline in the ABA/GAs ratio. (4) Conclusions: Pea seed treatment with a low KNO3 level promoted early seedling growth. In this process, an interaction among KNO3, antioxidant defences and ABA/GAs ratio is proposed.
Highlights
We assayed the effect of different KNO3 concentrations on the water uptake rate and germination rate of pea seeds
Lower KNO3 concentrations (0.25–5 mM) showed similar germination rates when compared to the control treatment at every day of treatment (Supplemental Table S1b)
The application of a low KNO3 concentration to dry pea seeds promoted early seedling growth, which was linked to the maintenance (APX, SOD, POX) and/or the increase seeds, as well as an enhanced seed germination by the exogenous application of H2O2, has been reported [6,32,43]
Summary
Seed germination is the most critical stage in crop establishment, determining crop production [1]. Numerous methods have been used to promote seed germination and seedling establishment under normal and stressful conditions. In this sense, seed priming, defined as a pre-sowing treatment which involves controlled hydration of seeds during the first stage of germination, has been widely applied to improve the germination rate and seedling growth under different stress conditions [2,3,4,5]. Likewise, seed chemical treatment during imbibition has been successfully applied for both fundamental research purposes and for the stimulation of seed germination and seedling vigour [6,7,8]
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