Effect of seed priming on germination and seedling growth of grain sorghum (<i>Sorghum bicolor</i> L. Moench) Varieties

Abstract

Sorghum (Sorghum bicolor L. Moench) is one of the leading drought-tolerant crops often used to mitigate droughts for meeting household food security in Ethiopia. However, poor stand establishment is one of the major factors that constrain productivity of the crop. Poor stand establishment of sorghum is affected by certain conditions after sowing, which have a large influence on speed of germination and seedling emergence that determine successful establishment of the crop under adverse growing conditions. Therefore, an experiment was conducted to elucidate the effect of seed priming on germination and seedling vigor of seeds of six sorghum varieties under a laboratory condition. The experiment was conducted during the 2014 main cropping season on the campus of Haramaya University. The treatments consisted of six sorghum varieties (Abshir, Dekeba, Macia, Meko-1, Melkam and Teshale), three priming media (water, 9 g urea L^-1, and 0.2 g ZnSO₄ L^-1) and five priming durations (0, 5, 10, 15 and 20 h). The experiment was laid out as a completely randomized design (CRD) in a factorial arrangement and replicated four times per treatment. The results showed significant (P < 0.05) main effects of the treatments and interactions between priming media and duration, and variety and priming duration for all the traits studied. The highest improvements in final germination percentage (FGP) (6%), germination-index (GI) (8.4%), germination time (MGT) (4%), emergence-percentage (EP) (20%), seedling-length (SL) (12.5%), seedling-dry-weight (SDW) (26.5%), seedling-vigor-index-1 (SVI-1) (33.1%) and seedling-vigor-index-2 (SVI-2) (49.7%) were recorded in response to seed priming using ZnSO₄ followed by priming with Urea and water for 10 h priming over the unprimed seeds (control treatment). Likewise, the highest varietal performance was recorded for Melkam followed by Teshale and Dekeba with 10 h priming. The reduction in MGT and the increments in FGP, GI, EP, SL, SDW, SVI-1, and SVI-2 due to variety Melkam with 10 h priming respectively were 5.7, 7.7, 3.8, 22.7, 13.6, 30.2, 38.1, and 58.8% over the unprimed seeds. Therefore, the priming sorghum seeds for 10 hours with ZnSO₄ followed by Urea and water significantly improved germination, seedling growth, and seedling vigor under laboratory conditions, implying that the practice priming seeds with each of the media based on availability and affordability could be used
by farmers to enhance sorghum seed germination, field stand establishment, and yield.

Keywords: Hydro-priming; Nutrient priming; Priming duration; Priming media; Vigor index