Maternal Environmental Effects of Temperature and Exogenous Gibberellic Acid on Seed and Seedling Traits of Four Populations of Evening Primrose (Oenothera biennis)

Abstract

Earlier studies have considered the separate effects of temperature and gibberellic acid (GA3) on plants and seeds. However, the combined effects of these factors on parent plants and their progeny have received little attention. We investigated the effects of two temperature regimes (24/20 °C and 28/24 °C, 16 h light/ 8 h dark) and two GA3 treatments (for two weeks) on the reproductive yield of parent plants, the subsequent seed germinability, and the seedling traits of four local populations of evening primrose (Oenothera biennis). Mature seeds were harvested and germinated, and seedlings were grown under the two temperature regimes. Parent plants were phenotyped for flower area and diameter, capsule length and width, full and empty capsule masses, and seed number and mass per capsule. Additionally, seed total germination and germination rate were determined, alongside stem height and dry mass, leaf number, area and dry mass, root dry mass, and total dry mass in seedlings. GA3 promoted the flowering of all populations in the first year. Maturation drying under higher temperatures resulted in more viable and faster germinating seeds. Higher GA3 did not affect total germination, but increased the germination rate of seeds that produced seedlings with lower total dry mass under the higher temperature regime. In conclusion, all populations responded similarly to GA3 treatment in terms of flowering, but responded differently to temperature during seed maturation, and subsequent seed germination and seedling growth.