Combining priming and plant growth regulators improves muskmelon germination and emergence at low temperatures

Summary The effects of incorporating plant growth regulators into the priming solution on low temperature germination and emergence performance of muskmelon [ Cucumis melo L. (Reticulatus Group) cv. 'Athena'] seeds were investigated. Seeds were primed for 6 days at 25°C in darkness in 3.5% (0.35 M) KNO 3 solution containing one of the following: 1, 3, 5 or 10 µM methyl jasmonate (MeJA), or 1, 3, 5 or 10 mM spermine. Following priming, seeds were subjected to germination and emergence tests at 15±0.5°C. Priming muskmelon seeds in the presence or absence of plant growth regulators significantly improved germination percentage, rate and synchrony at 15°C compared to untreated seeds. Inclusion of both MeJA and spermine at all concentrations except 10 µM MeJA resulted in higher germination percentages compared to seeds primed in KNO 3 only. The highest germination percentages were obtained from seeds that were primed in KNO 3 solution supplemented with 1 µM MeJA (96%) and 1 mM (94%) spermine. Moreover, the presence of both growth regulators in the priming solution improved low temperature emergence of muskmelon seeds compared to untreated seeds and seeds primed in KNO 3 solution alone. Inclusion of 1 µM MeJA and 3 mM spermine into the priming solution led to the highest emergence percentages with 90% and 85%, respectively, while priming in KNO 3 solution in the absence of plant growth regulators resulted in significantly lower emergence percentage (31%). Therefore, priming in 1 µM of MeJA or 3 mM spermine incorporated into the KNO 3 solution can be used as an effective method to improve low temperature performance of muskmelon seeds.