Evaluating the Effect of Osmotic Stress Tolerance in Maize Based on in Vitro Seed Germination.

Seed germination, controlled by both genetics and the environment, is an important process in the life cycle of corn (Zea mays L.). Drought is the major environmental factor influencing both germination percentage and rate. An experiment was conducted to evaluate in vitro seed germination responses of nine commercially available corn hybrids using polyethylene glycol (PEG 8000) to determine the impact of osmotic stress on the germination properties. These nine hybrids are common to dry land production systems in Mississippi and the US Mid-south region. Time series data for seed germination was generated at various osmotic potentials from 0 to -1.2MPa, at -0.3 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. Then, maximum osmotic potentials when seed germination rate and germination were zero were derived by fitting linear and quadratic regression models of seed germination parameters as a function of osmotic potential. Maximum seed germination and seed germination rate decreased with decreasing the osmotic potential for all corn hybrids. A cumulative drought response index (CDRI) developed by summing individual response indices of each parameter for each hybrid was used to classify corn hybrids into different drought-tolerant groups: drought tolerant, moderately drought tolerant, and drought sensitive. The identified tolerance among hybrids could help producers select the best hybrids suited for suboptimal water conditions. The functional Variation in response among hybrids could indicate the possibility of improving stress tolerance through selection and breeding programs. The functional relationships between osmotic potential and corn hybrids seed germination parameters will be useful to update corn models for field applications