Rooting Characters in Drought Tolerant Corn.

Corn (Zea mays L.), as a major cereal crop in the United States, is a major irrigated crop in the Texas High Plains. However, the declining water resource has imposed limitations to corn yields in this area, and will continue to do so in the future. Limited irrigation and adopting drought-tolerant (DT) hybrids were the two critical ways to stabilize corn production under water-limited conditions. Crop root characteristics are critical to use the soil water and have strong correlations with high yield under drought condition. We conducted a 2-yr (2014 and 2015) greenhouse study, including one conventional hybrids (33D53), two drought tolerant (DT) hybrids (P1151AM and N75H), one silage hybrid (NC300S2B73BC) under two water regimes (I₁₀₀ and I₅₀, referring to 100 and 50% evapotranspiration requirement), to investigate rooting characteristics and water depletion in DT corn hybrids. Among the hybrids, NC300S2B73BC had significantly greater root mass than other hybrids, while there was no significant difference in root mass between conventional and DT hybrids under both water regimes. However, compared with conventional hybrid, the proportion of root mass below 30 cm profile was higher for DT hybrids, especially under I₅₀ condition. Nevertheless, DT hybrids and silage hybrid had greater aboveground biomass and water use efficiency than conventional hybrid, and the differences were higher under I₅₀ condition than I₁₀₀ condition. The grain yields of DT hybrids were also higher than conventional hybrid, especially under I₅₀ condition.