Effects Of Supplemental Irrigation On Dryland Maize Growth And Yield

Water and nitrogen are the main factors that influence growth and yield of maize in arid and semi-arid regions. Supplemental irrigation in critical stages of maize can steadily improve yield and water productivity. A three-year consecutive field experiment(2013–2015) was conducted in Shouyang Experient Station of Ministry of Agirculture. The growth indexes, dynamics of soil moisture, and yield of spring maize under three levels of irrigation frequency and four levels of N application rate were measured regularly. The effects of supplemental irrigation in critical stages and nitrogen application rate on growth and yield of spring maize were analyzed. Major conclusions were des cribed as followings:1. Plant height, leaf area index and dry matter weight of shoot increased with increasing supplemental irrigation frequency and nitrogen application rate. The leaf senescence was slowed down with the increasing nitrogen application rate and the supplemental irr igation. Compared to no irrigation(W0), plant height, leaf area index and dry matter weight of shoot significantly increased(P<0.05) by 4.12%, 4.88% and 9.64% respectively under irrigation at jointing stage(W1), and increased by 6.24%, 8.05% and 27.78% under irrigation at both jointing stage and filling stage(W2). Compared with the non nitrogen condition(N0), the plant height, leaf area index and dry matter weight of shoot increased by 25.52%, 24.68%, 21.17% with low nitrogen rate(N1); 25.21%, 23.29%, 19.73% middle nitrogen rate(N2); 105.65%, 98.59%, 79.05% high nitrogen rate(N3) correspondingly. In terms of dynamic change of growth, supplemental irrigation at jointing stage increasd growth significantly(P<0.05), and at filling stage could inhibit leaf senescence, which benefit accumulation and transfer of assimilation in late growth stage.2. Yield of maize increased with supplemental irrigation frequency and nitrogen application rate signif icantly(P<0.05). Compared with W0, yield increased by 7.35%, 14.61% under W1 and W2. Compard with N0, yield increased by 182.57%, 150.62%, 128.28% under N3, N2 and N1 respectively. Supplemental irrigation increased yield by increasing grain numbers significantly, while nitrogen fertilizer by increasing grain numbers and 100-grain weight simutaneously. The optimum combination of supplemental irrigation and nitrogen application rate w ere N3W1 and N3W2.3. WUE increased with supplemental irrigation frequency and nitrogen application rate. Compard to W0, WUE increased signif icantly(P<0.05) by 12.04% under W2. Compared with N0, WUE increased by 9.19%, 7.96% and 7.16% under N3, N2 and N1 respectively. The increasement of yield with the supplemental irrigation was larger than the water consumption. This lead to the signif icant increasement of WUE.4. Nitrogen harvest index(NI) increased signif icantly(P<0.05) with supplemental irrigation frequency and nitrogen application rate, which indicated that irrigation and nitrogen application could promote nirtrogen transport to grain. N-use efficiency(NUE) and N agronomic efficiency(NAE) increased with increasing supplemental irrigation frequency. Irrigation increased NUE significantly only with less precipitation. NUE and NAE decreased with increasing nitrogen application rate. This result was consistent with the regulation that fertilizer efficiency was significantly increased by increasing fertilizer rate in the low fertility soil, with increasing fertilizer rate, fertilizer efficiency decreased.5. The water-nitrogen coupling effect had significant effect on NAE(P<0.01), the effect on NUE was signif icant under water deficited. The water-nitrogen coupling effect had no significant effect on growth and yield and WUE and so on.