Quality Assurance Strategies for Sweet Corn

Sweet corn seed quality has traditionally been determined by performing laboratory evaluations utilizing warm germination and cold germination tests. The resulting germination percentages are then employed to approximate field performance. These two tests, however, do not always predict field emergence. A study conducted by SGS Mid-West Seed Services evaluated thirty-nine sweet corn seed lots utilizing several alternative vigor tests for sweet corn to determine their relationship to warm and cold tests and to determine if a combination of tests may be the best approach to evaluate sweet corn seed quality. The quality of each seed lot was evaluated utilizing sand germination, cold germination, saturated cold, accelerated aging (AA), soak, pericarp damage and electrical conductivity tests. Association of Official Seed Analysts (AOSA) Rules (2007) were followed for all laboratory tests and seedling evaluations.

The results indicated that sand germination percentages demonstrated the least amount of variation of all laboratory tests performed, ranging from 83-99%. Cold, saturated cold and accelerated aging germination ranges were greater, 53-99%, 20-93% and 35-97%, respectively. The three other methods utilized also showed large results ranges; soak germination, pericarp damage, and electrical conductivity ranged from 56-98%, 2-36%, and 64-228%, respectively. From these results, baseline estimates for seed quality were developed.

Only two samples fell below 90% germination for the warm sand test, indicating that 37 of the seed lots were of good or high quality. However, it must be remembered that these results were obtained under ideal conditions. To better understand seed quality and how the seed will perform in the field, vigor tests should be performed. Possible baselines or quality cut-off points are indicated in Table 1. Cold and soak germination results above 80% are considered acceptable, while percent germination for AA can be 70% or above. The saturated cold test is generally the most stressful and results of 60% or higher are acceptable. Another test helpful in determining seed quality is the electrical conductivity (EC) test. Out of the 39 samples, 16 obtained results greater than the 130 uS/cm/g cut off. These baseline estimates are just a starting point and must be viewed as suggested guidelines for determining sweet corn seed quality.

Table 1. Suggested Baseline Criteria for Sweet Corn Vigor Tests

The results of field emergence testing on 10 of the 39 lots indicated that utilizing a variety of tests (warm germination, cold or soak and saturated cold) may be useful to help predict field emergence under a range of field conditions. As expected, lower field emergence percentages corresponded to stressful field conditions and were best reflected by cold, saturated cold and soak tests.



Brad Farber - Corn Laboratory Manager