After-Ripening and Stratification Improve the Germination of the Cakile maritima Scop. (Brassicaceae) from the Apulia Region, Italy

Understanding seed germination is crucial for refining the propagation techniques of Cakile maritima, a wild halophyte species with significant potential for biosaline agriculture. However, research on seed germination within intact fruits of this species is limited. Four trials were conducted to study the seed germination of a population from the Apulia region. The focus was on seeds that had undergone after-ripening for 3 years (20AR3) or 2 years (20AR2) (both collected in 2020), or 1 year (22AR1) (collected in 2022), and freshly harvested seeds in 2022 (22AR0) and 2023 (23AR0). The seeds were either incubated as naked or moist-stratified within intact fruits. A portion of 2022 AR0 siliques was submerged in saline water before stratification. The naked seeds collected in 2022 and 2020 (22AR0 and 20AR2) did not germinate, whereas a portion of the 23AR0 (67%), 20AR3, and 22AR1 (45%, irrespective of after-ripening) lots quickly (T50 = 3.5 days) germinated, underlining a lower dormancy level for seeds harvested or dry stored in 2023. Seed germination in the intact fruits was lower than the naked seeds, confirming the role of the pericarp in inducing seed dormancy. Stratification of the shelled seeds was much more effective in improving the germination time (140 days) and levels in the 23AR0 (81%), 20AR3, and 22AR1 (66%, irrespective of after-ripening) lots than in the 22AR0 (34%) and 20AR2 (61%) ones, which required 240 days to germinate. The saline solution imbibition of fruit seems only to delay the occurrence of the maximum emergence. The physiological seed dormancy of this C. maritima population has been proven, which may be variable in depth according to the year of fruit collection, ranging from intermediate to non-deep.