Accelerated Aging Test for Corn Seed

Although the accelerated aging (AA) test is recommended to measure soybean (Glycine max (L.) Merrill) seed vigor, a uniform AA procedure has not been developed for testing corn (Zea mays L.) seed. This study evaluated the effect of aging time, temperature and seed treatment on corn seed germination and related AA results to cold test germination and field emergence. Forty grams of fungicide treated and untreated seed from four seed lots across two hybrids were aged at 41 and 45°C for 72, 96 and 120 hours. Aging treated seed for up to 120 hours at 41°C caused no reduction in germination, however, significant reductions in germination occurred after 96 hours for untreated seeds. Both treated and untreated seed aged at 45°C showed significant reductions in germination after 72 hours. Two AA treatments (41°C, 96 hours, 45°C, 72 hours) which gave the best separation in seed lot vigorA were compared to tray cold test germination across many additional seed lots and several hybrids. Both AA procedures were highly correlated with each other, however, the germination levels were lower using the 45^C, 72 hour treatment. Neither AA procedure related well to cold test germination for treated seed. Standard germination, AA (45°C, 72 h) and cold test germination were related to field emergence in nine experiments across three years. A field emergence index (FEI, mean field emergence/mean standard germination x 100) for each planting date showed a range in field conditions from severe stress (FEI = <65) to near ideal (FEI = 97). The prediction accuracy (proportion of seed lots in each experiment that had >70 or 80% field emergence) was high for standard germination only in near ideal field conditions. As stress increased in the seedbed (FEI 75 to 90), at a minimum acceptable vigor level of >80%, both AA and cold test accurately predicted field emergence. Thus, the seed industry may want to consider both tests when screening genotypes for maximum field performance.