SMP: Solid matrix priming of seeds

Abstract

The purpose of these studies was to develop the technique of solid matrix priming (SMP) and then evaluate its ability to improve seedling establishment of small-seeded vegetable crops under either sub- or supra-optimal temperatures. SMP is a process in which seeds are mixed with a solid material and water in known proportions. This mixture allows the seeds to imbibe and attain a threshold moisture content, but prevents radicle emergence. The solid material used in these studies was a ground Leonardite Shale, “Agro-Lig”, which was a friable material and had a high water-holding capacity. The water potential of the Agro-Lig was determined after SMP and the osmotic potential accounted for >97% of the total water potential, which was attributed to solutes from the Agro-Lig and seed leachates. The matric potential contributed <1.5% of the total water potential. Seedling emergence studies were conducted on primed tomato ( Lycopersicon esculentum), carrot ( Daucus carota) and onion ( Allium cepa) seeds sown in an artificial soil media in flats maintained at 20 10° C with a 12-h photoperiod. The priming treatments consisted of polyethylene glycol 8000, inorganic salts and SMP. All priming treatments decreased the time for 50% seedling emergence and increased the plant dry weight compared with the non-treated controls for each crop. The seedling emergence characteristics of SMP-sown seeds were superior to, or equal to, conventional solution priming treatments. In addition, lettuce ( Lactuca sativa) seeds were primed with solutions or SMP and later germinated at 35°C in the dark. All priming treatments overcame thermodormancy.