Effects of Various Dormancy‐Reducing Treatments on Seed Germination and Establishment of Indiangrass, Sorghastrum nutans (L.) Nash 1

Spikelets of indiangrass, Sorghastrum nutans (L.) Nash, from cultivars ‘Cheyenne,’ ‘Holt,’ and ‘Osage’ were subjected to various dormancy‐reducing treatments and subsequently tested for laboratory germination and field establishment. Dormancy‐reducing treatments were: prechilling, hull removal, prechilling followed by hull removal, and hull removal followed by prechilling. A cultivar‐by‐treatment interaction occurred in normal laboratory germination, suggesting cultivar differences in level of seed dormancy, type of seed dormancy, or susceptibility to caryopsis injury resulting from the treatments. Abnormal laboratory germination followed only treatments involving hull removal. Prechilling significantly increased establishment from Holt spikelets and resulted in a nearly significant (.05) establishment increase with those of Osage. Establishment from Cheyenne spikelets was unaffected by prechilling. Establishment from spikelets of all cultivars was significantly reduced following treatments involving hull removal, although in some instances those treatments significantly increased normal laboratory germination. Economic feasibility of prechilling, as a practical means of improving indiangrass establishment, was considered questionable. However, in laboratory tests prechillng did not seem to remove all dormancy, indicating work with other dormancy‐reducing treatments is warranted. Regression analyses indicated that field establishment was affected by seed set and caryopsis weight as well as by spikelet germination. When dormancy was reduced through prechilling, the effect of normal spikelet germination on fieId establishment was largely attributable to variation in seed set. Statistical complications deriving from use of intact spikelets were discussed.