Synergistic improvement in spring maize yield and quality with micro/nanobubbles water oxygation

Soil oxygen shortages in root areas have negative effects on crop growth and decrease crops yield and quality, and soil hypoxia conditions will be aggravated by application of subsurface drip irrigation (SDI). A two-year field experiment was conducted to evaluate the response of maize to micro/nanobubbles oxygation (MNBO) at three dissolved oxygen (DO) concentrations (10, 20 and 30 mg/L) and seven MNBO periods (vegetative stage, reproductive stage, filling and ripening stage, combination of two stages and the whole growth stage) in addition to a control treatment (CK, no oxygation during the growth period). Our results revealed that the MNBO treatments increased maize root dry weight, root length density and root surface area in 0–20 cm soil. The highest yield was obtained in O(20)A (MNBO at 20 mg/L DO during the growth period), with an increase of 11.66% relative to CK. Crude ash, starch and vitamin C were improved by application of MNBO at 20 mg/L DO. However, excessive oxygen adversely affected maize growth, decreasing the maize yield in 2013 relative to CK. The results suggest that application of MNBO at 20 mg/L DO during the growth period of spring maize was appropriate.