Responses of root growth and distribution of maize to nitrogen application patterns under partial root-zone irrigation

A field experiment was carried out to investigate the effects of varying nitrogen (N) supply and irrigation methods on the root growth and distribution of maize (Zea mays L.) in Wuwei, northwest China in 2011 and 2012. The irrigation treatments included alternate furrow irrigation (AI), fixed furrow irrigation (FI) and conventional furrow irrigation (CI). The N supply treatments included alternate N supply (AN), fixed N supply (FN) and conventional N supply (CN), were applied at each irrigation method. The root growth across the plant row was measured in 0-100 cm soil profile (20 cm as an interval) at maturity. The results showed that root distribution of two sides of the row was uniform for AI or CI coupled with CN or AN. Root length density (RLD) in 0-40 cm soil depth was significantly increased by AI compared to other irrigation methods while decreased by FN compared to other N supply treatments. Though RLD decreased more with soil layer deepening under AI, RLD in 60-100 cm soil depth in AI treatment was still larger than that in CI and FI treatments. In general, total fine root (diametersurface area, and grain yield of maize were significantly increased by AI coupled with CN or AN when compared to other treatments. These results indicate that alternate partial root zone irrigation coupled with conventional or alternate nitrogen supply is useful to improve the root growth and grain yield of maize in the arid area.