Germination of Saccharum ravennae(L.)L.(Poaceae) caryopses and intact spikelets

Authors: Springer, Timothy; Goldman, Jason

Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/21/2015
Publication Date: 2/19/2016
Publication URL: http://handle.nal.usda.gov/10113/61960
Citation: Springer, T.L., Goldman, J.J. 2016. Germination of Saccharum ravennae(L.)L.(Poaceae) caryopses and intact spikelets. Crop Science. 56:682-688.

Interpretive Summary: Ravenna grass is a robust perennial bunchgrass grown as an ornamental in the United States, but where adapted, has become naturalized in riparian areas. Based on genetic markers, variation existed between the two naturalized populations investigated. Although seed production of Ravenna grass is relatively low, under favorable conditions it can produce more than 10,000 caryopses (grain) per panicle (seed head). The amount of precipitation received each year influences number and weight percentage distributions. In drier years, fewer, but heavier caryopses are produced and in wetter years, more, but lighter caryopses are produced. Caryopses germinated completely in 14 days and averaged more than 80% germination. Caryopses with weight of 0.34 mg or more germinated similarly averaging more than 90% germination. Intact spikelets (grains within husks) were slower to germinate in 14 days compared with caryopses. Intact spikelets also had a significantly higher percentage of firm (non-germinated) seeds compared with caryopses and the total potential germination of intact spikelets was greater than caryopses exceeding 90%. Ravenna grass is relatively unpalatable to livestock and wildlife, but has the potential to be grown for its biomass to be used for energy production. Research is needed to determine optimum seeding rates and plant densities to sustain long-term biomass production.

Technical Abstract: Ravenna grass, Saccharum ravennae (L.) L., is a robust perennial bunchgrass grown as an ornamental in the United States, but where adapted, has become naturalized in riparian areas. Little is known about the seed size distribution and germination characteristics of caryopses and intact spikelets. Thus, our objectives were to determine: 1) the genetic relationship to naturalized populations using molecular markers, 2) the caryopsis size distribution on the basis of caryopsis weight and number, 3) the germination of sized caryopses, 4) the length of seedling shoots and roots from caryopses of different sizes, 5) the germination of unsized caryopses and intact spikelets, and 6) the length of seedling shoots and roots from unsized caryopses and intact spikelets. Based on genetic markers, variation exists between the two populations investigated. Although seed production of Ravenna grass is relatively low, under favorable conditions it can produce more than 10,000 caryopses per panicle. All caryopses germinated within 14 days and averaged more than 80% germination. Caryopses with a mass of 0.34 mg or more germinated similarly, averaging more than 90% germination. Intact spikelets were slower to germinate in 14 days compared with caryopses 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 intact spikelets was greater than caryopses exceeding 90%. Understanding the germination characteristics of Ravenna grass will aid in the development of seeding rates and the processing of seeds for agronomic purposes.