Influence of flowering phenology on seed production in smooth cordgrass (Spartina alterniflora Loisel.)

Abstract Smooth cordgrass (Spartina alterniflora Loisel.), a dominant salt marsh grass along the Atlantic and Gulf Coast of North America, is used extensively for reclamation and restoration of eroding coastal wetlands. Aerial seeding is both economical and practically feasible to vegetate large areas of marsh land. It can accelerate coastal restoration efforts by replacing the expensive hand planting of vegetative clones. However, unavailability of large quantities of viable seed, due to poor seed set in S. alterniflora , is a major hindrance. Our objective was to study the effect of flowering phenology on seed production in 20 native smooth cordgrass accessions collected from south Louisiana. Flowering initiated in early July and ended by middle of October, with peak flowering between early September and early October. Total florets per panicle decreased as the season progressed while the seed set and 1000-kernel weight steadily increased. Thousand-kernel weight, flowering date, and seed weight per panicle showed positive correlation with seed set, and direct effects of these traits were significant, as revealed in path-coefficient analysis. The average seed set was 47 ± 2%. The range of 0–94% provides an opportunity to identify superior lines for developing populations with improved seed production. It is evident from this study that flowering is an important determinant influencing seed set, and selection could be made for plants that flower within the peak flowering period resulting in the highest number of filled seeds with improved germination and higher kernel weight.