Effects of waterlogging at different stages on growth and ear quality of waxy maize

A waterlogging experiment under a rain shelter was used to investigate the response mechanism of waxy maize plant growth, ear yield, and quality to waterlogging at various growth stages. Waterlogging for 10 d were carried out at V6-VT (WV6-VT), VT-R1 (WVT-R1) and R1-R3 (WR1-R3) stages of waxy maize in lysimeters in 2019 and 2020 seasons, and non-waterlogging was used as control (CK). The results showed that waterlogging at V6-VT had the highest impact on waxy maize growth, fresh ear yield, and grain quality, followed by that at the VT-R1, and finally that at the R1-R3. During the waterlogging at V6-VT, the growth of waxy maize plants was accelerated, while the gas exchange parameters in leaves were decreased, however the plant height, leaf area index (LAI), and gas exchange parameters of the WV6-VT treatment were significantly lower than those of CK at R3. Compared with CK, the content of malondialdehyde (MDA) and the activities of superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) in leaves increased, whereas the contents of soluble sugar, soluble protein and proline in leaves decreased. As a result, waxy maize ear length, grain number per ear, 100-grain weight, and fresh ear yield fell, and grain quality suffered as well. Total protein and soluble sugar content in grains decreased, but starch and lysine content in grains increased. Principal component analysis (PCA) revealed that when waterlogging for 10 d occurred in waxy maize, it was the first to alter maize growth and physiology, and then affecting grain quality. Waterlogging at V6-VT waxy maize were the most severe, followed by VT-R1 and R1-R3.