Root and Shoot Responses of Summer Maize to Waterlogging at Different Stages

The specially designed soil columns experiment was conducted to determine effects of waterlogging for 6 d at the third leaf stage (V3), the sixth leaf stage (V6), and the 10th day aft er the tasseling stage (10VT) on root growth and development of summer maize (Zea mays L.). Results showed that waterlogging significantly decreased root length, root length density, and number of root tips compared to the control (CK). Waterlogging significantly reduced the total absorption area and active absorption area with the most significant reduction in treatment at V3. The active absorption area of roots at V6, tasseling (VT), milking (R3), and physiological maturity (R6) stages decreased by 68, 67, 57, and 67%, respectively, due to waterlogging at V3. In addition, waterlogged plants generally had much lower root bleeding rates, which were significantly decreased by 46, 28, and 13% from the control by the treatment at V3, V6, and 10VT stages, respectively. The negative effects of waterlogging on root growth and development led to abnormal development of the aboveground biomass, resulting in signifi cant reductions in dry matter, leaf area, net photosynthetic rate, and yield. Compared with grain yield of CK, yields under the treatments at V3, V6, and 10VT stages were reduced by 26, 21, and 13%, respectively. Responses of summer maize root growth and grain yield to waterlogging depended on the growth stage. Summer maize was most susceptible to waterlogging damage at V3 stage, followed by V6 and 10VT stages.