Alternate partial root-zone drying irrigation improves nitrogen nutrition in maize (Zea mays L.) leaves

The effects of alternate partial root-zone drying (PRD) irrigation as compared with conventional deficit irrigation (DI) and full irrigation (FI) on leaf nitrogen (N) accumulation were investigated in maize (Zea mays L.) grown under three N-fertilization rates (1.5, 3.0, and 6.0 g N pot−1). The plants were grown in split-root pots in a glasshouse and were exposed to FI, PRD, and DI treatments from the seventh leaf to tasselling/silking stage. The results showed that neither irrigation nor N-fertilization treatments influenced shoot biomass and plant leaf area; while PRD plants had the highest root biomass and root to shoot ratio compared to DI and FI plants. Increase of N rate significantly increased leaf N accumulation; across the N-fertilization rates, PRD and FI plants accumulated significantly greater amount of N in leaves than did DI plants. Leaf δ15N decreased significantly with increasing N-fertilization rate, and was significantly higher in PRD and FI than in DI plants. Water use efficiency (WUE) was the highest in PRD, followed by DI and the lowest in FI; while N-fertilization rate had no effect on WUE. It was concluded that an enlarged root system and an enhanced soil N availability under PRD might have contributed to the greater N accumulation in maize leaves.

► PRD is superior to DI in enhancing crop WUE and leaf nitrogen (N) accumulation in maize.
► PRD enhances root growth and root to shoot ratio in maize plants.
► Natural 15N signature in maize leaves is enriched by PRD.
► A larger root system and a greater soil N availability account for the higher leaf N nutrition in PRD.