Seed Germination Responses to Osmotic Stress in Corn Cultivars.

Seed germination, controlled by both genetics and the environment, is an important process in the life cycle of corn (Zea mays L.). Drought is one major environmental factor influencing both germination rate, and maximum germination. An in vitro experiment was conducted using polyethelene glycol (PEG 8000) to examine the impact of osmotic stress on the germination properties of six commercially available corn hybrids. Three hybrids contained a known drought tolerant gene package, advertised to perform better under rain fed conditions (P1498, DKC 65-81, and N59B-3111A), while the other three hybrids contained no reported drought tolerance mechanisms (P1319, DKC 66-97), and N61X-3110). Time series data for seed germination was generated at various osmotic potentials from 0 to -0.9MPa, at -0.2 MPa intervals while the seeds incubated at 25°C. Maximum seed germination, time to 50% germination, and seed germination rate were derived by using appropriate regression analysis. A cumulative drought response index (CDRI),developed by summing individual response index of parameters, was used to classify corn hybrids into three drought-tolerant groups. The identified tolerance among hybrids could help producers select the best hybrids suited for suboptimal water conditions.