Abstract：Irrigation methods may have important influences on spring maize root growth. To investigate the effects of ridgefurrow irrigation method on the root growth and distribution of spring maize, three methods, namely conventional furrow irrigation (irrigated both sides equally, CI), alternate furrow irrigation (alternatively irrigated between north and south sides, AI), fixed furrow irrigation (irrigated one side only, FI) are attempted under field condition. The root system growth states in 0-100 cm thick soil (five layers, each 20 cm thick) located at the north and south sides of the plants are measured at tasselling, filling and maturity growth stages. The results show that the root length density of the maize irrigated with AI is larger than that with FI in 0-40 cm thick soil layer; but the density by CI is smaller in 60-100 cm soil layer. The root length density of the maize irrigated with FI in the south side is significantly different from that in the north side, however those of the maize irrigated with CI and AI don′t show such an effect. Also, the root total length and dry mass of the maize plant irrigated with AI are larger in 0-100 cm thick soil layer in the monitoring periods. Compared with FI, the grain yield, biomass yield and irrigation water use efficiency with AI are improved by 17.37%, 1842% and 17.45%, respectively. The performance of CI is in between AI and FI. The root growth and distribution in 0-40 cm thick soil layer at both sides of the plants are more greatly affected by soil water content at taselling stage. Obviously, a local irrigation is useful for root to grow in the deep soil layer, and the root growth and distribution at both sides of the plants are mostly influenced by irrigation method at tasselling stage. The root distribution is relatively uniform for the maize irrigated with CI and AI. Compared with FI and CI, AI not only can promote root growth but also increase maize yield and improve irrigation water use efficiency.
