Seed Set in Prairie Cordgrass

Abstract

ABSTRACTPrairie cordgrass (Spartina pectinata Link) has potential for biofuel production in soils too wet for switchgrass (Panicum virgatum L.). However, poor seed set is a major impediment to seed production in this species. Our objectives were to (i) estimate frequency of seed set (i.e., normal caryopsis in spikelet) and seed predation by insects and (ii) partition variance for seed set into environmental and morphological sources for a population of prairie cordgrass selected for biofuel production. During 2005 through 2011, panicles were collected from nurseries of the selected population in South Dakota and Illinois. Seed set was 79% for 1‐ and 2‐yr‐old stands indicating neither poor seed set or seed predation, which ranged from 0 to 15%, by Aethes spartinana (Barnes & McDunnough) (Lepidoptera: Tortricidae) seriously limited seed production. Most of the variation in seed set could be accounted for by variation among and within panicles within nurseries. Spikes in the distal two‐thirds of the panicle had higher seed set and lower seed predation than those in the proximal one‐third. However, variance between spikes from similar panicle positions accounted for more of the variation in seed set than any other spatial or morphological source. Therefore, increased understanding of seed set, which is subject to environmental vagaries from heading through seed development, will require sampling emphasis at the spikes within panicles and spikelets within spikes levels.