Effects of Chemical and Physical Treatments on Germination of Freshly‐Harvested Kleingrass Seed1

Abstract

Freshly‐harvested kleingrass (Panicum coloratum L.) seed exhibit post‐harvest dormancy (approximately 10 to 20% germination) which is essentially lost following 6 months storage at room temperature. The purpose of this investigation was to determine if physical and chemical seed treatments can circumvent or alleviate this dormancy. For all experiments, total germination of seed was determined over a 35 d period (35/25°C, day/night temperature, 12 h light). Seed from several genotypes were included so that tests for treatment ✕ genotype interactions could be made. Sulfuric acid (H2SO4) treatments were most effective in promoting germination of freshly‐harvested seed (three separate experiments). As scarification requirements (for hard seed) do not disappear with time, our data suggest acid treatments either a) destroy a germination inhibitor, or b) modify the lemma and palea to allow inhibitors to diffuse out of the caryopsis. Several other treatments increased germination slightly. Untreated seed stored for 6 months at −20°C were essentially dormant after storage. This dormancy was greatly reduced by sulfuric acid treatments. Germination of untreated seed stored at room temperature for 6 months increased from 27 to 92%. Germination of the seed stored at room temperature was increased to a maximum of 96% by several treatments, although sulfuric acid treatments were no longer the most effective. This suggests different levels or mechanisms of dormancy exist even within seed from a specific genotype, so that as seed age, their response to various chemicals change. For all experiments, significant differences between genotypes and treatments were noted, and treatment ✕ genotype interactions were significant. Hence, use of a given chemical (i.e., sulfuric acid) on a bulk seedlot may differentially stimulate germination or injure certain genotypes present in the seedlot.