Germination of sh2 Sweet Corn following Seed Disinfestation, Solid-matrix Priming, and Microbial Seed Treatment

Sweet corn (Zea mays L.) cultivars carrying the sh2 mutation show poor seed vigor under stressful field conditions, requiring higher seeding rates to ensure stand establishment. The effects of sodium hypochlorite seed disinfestation, solid matrix priming (SMP), and seed-coating with Gliocladium virens Miller, Giddens & Foster to enhance emergence of sh2 sweet corn in controlled-environment cold stress tests and field trials were investigated. In combination with a chemical fungicide seed treatment (captan, thiram, imazalil, and metalaxyl), SMP significantly improved the percentage and rate of seedling emergence of ‘Excel’ and ‘Supersweet Jubilee’ in a cold stress test (in soil for 7 days at 10C, then 15C until emergence) but was inconsistent under field conditions, improving emergence in only one of four field trials. Sodium hypochlorite disinfestation was ineffective. Compared to a film-coated control, coating seeds with G. virens strain G-6 was highly effective in increasing emergence in two of three cultivars tested in cold stress tests in two soils, while strain G-4 was generally ineffective. In field trials, G-6 treatment significantly increased emergence over that of nontreated seed but was inferior to conventional fungicide treatment and conferred no additional benefit in combination with fungicide treatment. Overall, no seed treatment evaluated was an economically viable alternative for or supplement to chemical fungicide treatment. Chemical names used: cisN-trichloromethylthio-4-cyclohexene-1,2-dicarboximide (captan); tetramethyl-thiuram disulfide (thiram); 1-[2-(2,4-dichlorophenyl)-2-(2-propenyloxy)ethyl]-1H-imidazole (imazalil); N-(2,6-dimethylphenyl)-N-(methoxyacetyl)-alanine methyl ester (metalaxyl). Table 1. Effect of sodium hypochlorite (NaOCl) and solid-matrix priming (SMP) on seedling emergence of sh2 corn in a 1992 controlledenvironment stress test.z