Effect of potassium nitrate priming on seed germination of seashore paspalum

Germination of seashore paspalum (Paspalum vaginatum Swartz) is a critical factor influencing seedling establishment when seeded directly in fields. In this research, pregermination priming with osmotic solution was used to improve the germination percentage of seashore paspalum. The goal of this study was to develop techniques that improve the germination of a seashore paspalum cultivar (SeaSpray). Seeds were subjected to priming in petri dishes with solutions of KNO₃ at 25°C for 24, 48, and 72 h in growth chambers. Germination percentage differed by priming duration as well as concentration of priming media. Based on the germination percentage 14 days after imbibition, the most promising priming condition was the treatment with 0.2% or 0.5% KNO₃ for 72 h at a constant temperature of 30°C and 0.2% or 0.5% KNO₃ for 48 to 72 h at alternating temperature of 25/35°C. Both concentrations showed reasonable germination percentage greater than 85% at alternating temperature condition. Priming with KNO₃ solution for 48 to 72 h improved not only germination percentage, but also uniformity. The increased duration of priming with KNO₃ was positively correlated with an improved germination percentage. The effect of increasing concentration was the most apparent at a constant temperature (30°C) regime with the treatment of 0.2% KNO₃ priming. Germination percentage was increased from 34.3% to 68.0% 2 weeks after imbibition (WAI) as the priming duration was increased from 24 to 72 h. Priming with KNO₃ for 3 days also had a modest effect on germination percentage (greater than 74.7%) at 1 WAI. Therefore, priming with 0.2% or 0.5% solution of KNO₃ for 72 h is a recommended method that can be practically applied for increasing germination of paspalum under an alternating temperature (25/35°C) condition. The regression analysis between odds of germination percentage and germination time showed that priming treatment increased internal activities during the second stage of seed germination.