Evaluating Corn Hybrid Variation in Response to Soil Moisture Stress.

Drought is a significant abiotic stress in corn (Zea mays L.) with around 40% of potential yield unrealized because of suboptimal water availability. The objective of this study was to assess soil moisture stress tolerance (drought tolerance) among 19 commercially available corn hybrids during early growth stages. Hybrids common to Mississippi production systems from a wide variety of retail seed companies were selected for this study. Two experiments were conducted where plants, grown in pots outdoors, were subjected to three different soil moisture regimes, namely 100% (control), 66%, and 33% based on field capacity, from 5 to 22 days after sowing (DAS). Plant morphology and growth, including several root traits, were measured at the end of the experiment. Physiological parameters, including fluorescence, leaf pigment characteristics, and leaf level photosynthesis were recorded at 21 DAS. Most shoot, root, and physiological parameters decreased as soil moisture levels decreased, and differed in their response by hybrid. Drought response indices were created for each parameter by dividing treatment values by the control value, thus expressing the stress effect on a scale of 0 to 1. A cumulative drought response index was developed by summing individual drought response indices for each parameter and was used to classify hybrids into groups of tolerance: drought tolerant, moderately drought tolerant, and drought sensitive. The variation of sensitivity identified among the corn hybrids indicates the possibility of validating hybrids with drought tolerance. Future research will include studying the effects of drought at different growth stages.