Germination of Saccharum ravennae (L.) L. (Poaceae) Caryopses and Intact Spikelets

Abstract

Ravennagrass, Saccharum ravennae (L.) L. [synonym: Erianthus ravennae (Linn.) P. Beauv.], is a robust perennial bunchgrass grown as an ornamental in the US, but, where adapted, has become naturalized in riparian areas. Little is known about the seed size distribution and germination characteristics of ravennagrass caryopses or intact spikelets. The objectives of this study were to determine, for two populations: (i) the caryopsis size distribution, (ii) the germination of sized caryopses, (iii) the length of seedling shoots and roots from caryopses of different sizes, (iv) the germination of unsized caryopses (UC) and intact spikelets (IS), and (v) the length of seedling shoots and roots from UC and IS. Although seed production of ravennagrass is relatively low, under favorable conditions, ravennagrass can produce more than 10,000 caryopses per panicle. Caryopses germinated well within 14 d and averaged >80% germination; however, caryopses germinated >90% if their mass was >0.3 mg. Intact spikelets were slower to germinate in 14 d and had a lower percentage of abnormally germinated seed compared with caryopses. Intact spikelets also had a significantly higher percentage of firm seeds compared with caryopses and the total potential germination of IS was greater than caryopses exceeding 90%. Understanding the germination characteristics of ravennagrass will aid in the development of seeding rates and the processing of seeds for agronomic uses.