| Northeast China is one of the most important maize production areas in China. In this region, the seasonal and spatial distributions of precipitation distributed unevenly. For example, seasonal drought usually happens. Therefore, to investigate the effects of the drought-resistant measures of plastic film mulch and drip irrigation strategies on maize yield and water-nitrogen use efficiency, and explore the cultural technique system of high yield and high resources use efficiency simultaneously in Northeast China is urgent to ensure national food security and protect resources and environment. Through field experiments, we analyzed the effect of plastic film mulch on maize yield and water use efficiency (WUE) in different precipitation years and the underlying mechanism, and investigated the effect of drip irrigation strategies on maize yield and water-nitrogen use efficiency. The main results were concluded as follows:1. According the Four site-year field experiments, we found plastic film mulch (PM) significantly increased maize yield by15%-26%in the dry years compared to the control treatment (CK) while no significant yield improvement was observed in the rainy years. Yield increase in the dry years was mainly due to a large increase in dry matter accumulation pre-silking compared to the CK, which resulted from a greater dry matter accumulation rate due to the higher topsoil temperature and water content. As a result, bothgrain yield and WUE in thet PM treatment was improvedcompared to the CK. In the rainy years, due to frequent precipitation and scant sunshine, the topsoil temperature and water content in the field that received PM treatment was improved only at some stages and failed to cause higher dry matter accumulation. Consequently, the grain yield and WUE were not improved by PM use in the rainy year.2. Through the density experiments, we found grain yiled at high (67500plant ha-1) and middle (67500plant ha-1) density were significant higher than the low density (45000plant ha-1) under plastic mulch. Compared to the low density treatment, the high and middle density treatments significant increased the ear per ha and the total dry matter. Similar yield was observed between high and middle density treatments. Compared to the high density treatments, the middle density treatment increased the grain filling rate of inferior grains, regulated the spatial distribution of population root system, and improved the root-shoot ratio, then obtain a high yield level although the ear per ha of middle density was lower than hight density.3. Using three different drip irrigation tubes (Traditional Type and New type) x three different lateral burying depths (0,5and10cm) in fields, it showed the new drip irrigation (NDI) tube under gravity irrigation displayed a higher velocity. The NDI with5cm lateral depth significantly increased grain yield by20.1%, which increased maize yield by8.8%comparing to the traditional drip irrigation with the same depth. The higher yield in NDI treatment with5cm lateral depth resulted from the delayed leaf senescence and higher total dry matter. Meanwhile, WUE in NDI with5cm lateral depth was increased by10.9%. Therefore, NDI with5cm lateral depth could be to be an effective strategy to increase both maize yield and water use efficiency.4. Based on the irrigation x nitrogen experiments, which inluded four irrigation amount (120%ET,100%ET,80%ET,60%ET) and three nitrogen fertilizing rates (N90, N180, N360), it showed that both yield and water-nitrogen use efficiey of80%ET was not significant difference compared to the100%ET with180kg ha"1N rate, which implicated80%irrigation rate couldalco achieve a higheconomic return.5. According field experiments with three treatments,(rainfeed mazie (RF); flood irrigation (FI), drip irrigation (DI)) under different plant density, the yield of RF was the lowest at all densities. Comapared to FI, the yield of DI was no significant difference at the middle density (67500plant ha-1), but DI yield increased by6.7%at the high density (90000plant ha-1). At the high density, DI treatment obtained higher leaf area index and total dry matter accumulation, and significantly improved water and nitrogen use efficiency. So, DI can improve suitable planting density of spring mazie in Norhteast China. |
PDF Full Text Request