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Drought conditions after sowing threaten the seedling establishment of all seeds, including cover crops. Cover crops are commonly broadcast and, thus, are often susceptible to drought stress after sowing. Our hypothesis was that seed coating with superabsorbent polymers (SAPs) would enhance germination in the lab and stand establishment in the field by increasing water availability to single seeds. Red clover (Trifolium pratense L.) seeds were coated with the following selected SAP formulations at 2% of their seed weight: cross-linked potassium polyacrylate (PAL), cross-linked polyacrylamide-based polymer (PAM), PAM with graphite (PAM+G), and Starch-g-2-Propenoic acid (potassium salt) (STR). The water absorbency of each SAP formulation was >200 g water/g of polymer; STR had the greatest absorbency, at 352 g water/g of polymer. A seed coating method was developed, resulting in the uniform application of SAP from seed to seed. All SAP coating treatments increased germination compared to the 0% SAP coating in controlled environment studies in the lab. Three field trials were conducted for each seed coating treatment, providing a range of climatic soil conditions. Within each field trial, the STR with the greatest water absorbency had a higher stand for treatments sown by broadcasting followed by raking to incorporate seeds. The first two trials were conducted under more stressful conditions. PAM+G performed best in the first two trials by broadcasting seeds with no raking. Collectively, the selected SAP seed coating improved field stands compared to the non-treated controls.

The purpose of this research was to collect efficacy data on biological, biochemical, and chemical fungicide seed treatments on hemp (Cannabis sativa L.) to mitigate damping-off and enhance field stand establishment. Seed treatments were evaluated in fields in New York (NY), North Dakota (ND), and Virginia (VA) and at two planting dates in each state in 2020. A single seed lot of a dual-purpose (fiber + grain) cultivar (‘Anka’) was treated using a laboratory-scale rotary pan coater. Five biological, two biochemical, and four chemical seed treatments were tested. A laboratory germination test revealed that seed treatments did not exhibit phytotoxicity when compared to the non-treated control. A laboratory bioassay with naturally infested soil was used to assess the preliminary activity of seed treatments for protection against damping-off. The biochemical seed treatment Ultim® (active ingredient; organic copper) performed as well as the chemical treatments Apron XL® + Maxim® 4FS and Mertect® 340F in preventing damping-off whereas the biological treatments did not differ from the non-treated control in terms of disease incidence. In all field tests, biological seed treatments did not improve plant stands compared to the non-treated control. Biochemical seed treatments Prudent 44® with Nutrol® (active ingredient; phosphite) and Ultim®, along with chemical seed treatments, had acceptable efficacy and improved stand establishment compared to the non-treated control across field locations. Based on efficacy results from laboratory and field trials, the copper seed treatment has potential for both conventional and organic hemp production.

The focus of this research was to evaluate genotypes for cold-tolerant germination from wild switchgrass (Panicum virgatum L.) populations collected in the Northeast USA. Switchgrass nurseries were established in 2008 and 2009 with seed collected from native stands of switchgrass in the Northeast USA between 1991 and 2008. Switchgrass seed harvested from individual genotypes was evaluated for cold-tolerant germination in a series of laboratory experiments. Germination assays of seed of 13 switchgrass genotypes harvested in the fall of 2016 are the primary focus of this reported research. The selected genotypes were evaluated for cold-tolerant seed germination in three experiments, during the spring of 2017, fall of 2017 and spring of 2018, (with and without stratification) using a 10/15 °C regime with a 12 h photoperiod. Germination tests showed that several genotypes had significantly higher percentage germination as well as faster germination rates expressed as T50 (number of days required to reach 50% maximum germination) when compared to Cave-in-Rock, a moderately sensitive cold-tolerant commercial cultivar established in the original switchgrass nursery as a control. A final germination test was conducted to compare seed from the original population (no selection cycle 0), with one of the top performing cold-tolerant germination genotypes, and a commercial cultivar, ‘Espresso’, developed for low seed dormancy and low temperature germination. In this test, the selected genotype had significantly higher percentage germination in the stratified treatment and was not significantly different than Espresso in the non-stratified test. These data indicate successful selection for cold-tolerant germination in switchgrass genotypes from native germplasm collected in the Northeast USA.