Dry Storage And Use Of Potassium Nitrate Breaks Dormancy And Improves Seed Germination In Sesamum Latifolium (Gillet)

Abstract

Seeds of Sesamum latifolium, a medicinal species and wild progenitor of the cultivated Sesame (Sesamum. indicum), have been reported to express dormancy of non-deep physiological nature at maturity. Seed dormancy is not only known to hamper species utilization as a crop or in crop improvement and other related research but also impedes viability assessments through a germination test. This study examined germination response of S. latifolium to potassium nitrate and preheating (also referred to as dry storage or dry after-ripening) with a view to using these processes as appropriate dormancy release stimulus. Four levels (0.0%, 0.15%, 0.2%, & 0.25%) of potassium nitrate and/or eight pre-heating periods at 45oC were used to investigate this response. Germination tests were carried out at three different incubation temperature regimes (25/25°C, 35/20°C and 35/15°C) using both pre-stored and freshly harvested seeds. The results reveal positive response to both potassium nitrate and pre-heating. It is recommended that in assessing seed viability of this species through a germination test, seeds should be preheated for one to three days before sowing on germination media containing 0.15 – 0.25% potassium nitrate and incubating at an alternating temperature of either 35/20ºC or 35/15ºC.