Physiological and biochemical responses to seed priming with polyethylene glycol under variable temperatures in soybean

Unfavorable temperatures during germination can significantly disrupt the physiological and biochemical processes crucial for seed germination, posing a challenge to soybean crop establishment and overall yield potential. Seed priming has emerged as a technique that has the potential to enhance crop establishment under high-temperature stress conditions. The presented study evaluated the impact of seed priming [without seed priming, hydropriming, and osmopriming with polyethylene glycol (PEG) 6000 @ −0.5, −1.0, −1.5 and −2.0 megapascal (MPa) for 6 h] at different temperatures (25, 30, 35, and 40℃) on physiological and biochemical parameters under controlled conditions. The experiment was conducted twice in factorial complete randomized design, each replicated four times. The results showed that seed priming with PEG @ −1.5 MPa recorded higher speed of germination, germination percentage, total seedling length, seedling dry weight, and vigor indices at 30 °C than other seed priming treatments and temperatures. Seed treated with PEG @ −1.5 MPa recorded higher speed of germination (15.3 and 8.2%), seedling vigor index I and II (19.6% and 13.0%, and 10.3% and 6.5%) over control and hydropriming, respectively. Compared to other priming treatments, PEG @ −1.5 MPa primed seeds exhibited significantly lower electrical conductivity, higher dehydrogenase activity, and higher percentage of stained seeds at the different temperatures tested (25, 30, 35, and 40℃). This implies that seed priming with PEG @ −1.5 MPa could serve as a valuable method to enhance the physiological and biochemical parameters of soybean at high temperatures, potentially fostering early plant development and augmenting yield potential.