Effects Of Different Cultivation Management Practices On Dry Matter Accumulation And Water-Nitrogen Utilization Efficiency Of Spring Maize On The South Loess Plateau

In recent years, maize had became a major grain crop in the northwest semiarid region especially the Loess Plateau. Despite the availability of modern hybrids and better agronomic practices, there still presented large gaps between attainable yield of maize grown with recommended practices and potential productivity on the Loess Plateau. In order to solve the problems, a field experiment was conducted for 2 years in Changwu, Shaanxi (35.2°N and 107.8°E). Based on the Hybrid-Maize model we designed several cultivation management practices(high-yield practices), and the normal farmer practices were used as the control treatments. The objectives of this study were: (a) to study the effects of the different cultivation management practices on the growth and yield of spring maize, (b) to illustrate the effects of nitrogen and dry matter accumulation and distribution at different management practices, (c) and to recommend a high-yield cultivation management practices according to maize grain production , WUE (water use efficiency) , NUE (nitrogen use efficiency).The main results were showed as follow:1. The cultivation management practices significantly influenced dry matter absorption and distribution. The plastic film mulching treatment had significant positive effect on shoot biomass and dry matter accumulation of maize grain, compared to the non-covered cultivation practice. It indicated that the plastic film mulching treatment can significantly increase the dry matter accumulation and the grain yield. The vegetative organs such as leaves at the later growth stages had powerful assimilation capacity at high-yield practices, therefore the net translocation of dry matter and the contribution ratio to yield were less than those of the control treatments especially for the non-covered cultivation practice .2. Under high-yield practices, the leaves and stems which accumulated dry matter as the storge organs, continued to accumulate lagre amounts of dry matter during the later growth stages, indicating a promotion of assimilation capacity in maize. Grain yield varied significantly among cultivation practices, ranked as follows: high-yield practices > normal farmer practices. High-yield practices especially the uncovering membrane at later growth stages increased the grain yield, likely because of preserving the root activity and prolonging the reproductive stages. 3. The treatment mulched with plastic film had increased the biomass and grain yield, decreased the soil water evaporation, therefore it significantly increased the water use efficiency of grain and biomass. The water use efficiency in high-yield practices was significantly higher than in normal farmer practices, indicating the further improvement of the grain yield and water use efficiency. The treatment with uncovering membrane at later growth stages increased the soil water evaporation and decreased the water use efficiency, but it played a positive role in increasing yield.4. The N accumulation of shoot and grain in plastic film mulching treatment were significantly higher than those in corn straw mulching and rain-fed treatment. The N accumulation was in consistent with the grain yield evolving in all treatments. The plastic film mulching treatment increased the N use efficiency, N harvest index and N productivity efficiency, similarly enhanced the convention of plant absorbed N into grain yield or dry matter. The treatment with uncovering membrane at later growth stages promoted the photosynthesis assimilation and the N absorption, while the N use efficiency and N productivity efficiency were higher than other high-yield practices. The N harvest index of high-yield practices were higher than normal farmer practices, indicating a promotion of N transportation from vegetative organs to the seeds.5. Hybrid-Maize model had a good simulation effect on the Loess Plateau. Correlation analysis indicated that there was a highly significant correlation between simulated data and observed data. We conclude that the Hybrid-Maize model had a good simulation effect on the growth process of maize and yield both in plastic film mulched and non-covered treatment on the Loess Plateau, therefore, the Hybrid-Maize model has good application value on guiding maize high yield cultivation.6. Consideration of productive factors, using whole covering on double ridges and planting in catchment furmws(WCDR-PCF), selecting upright-leaf variety, increasing plant population density, uncovering membrane at later growth stages, and increasing N application ratio at later growth stages were benefit for high yield in spring maize on the Loess Plateau, while the conclusion was supported by Hybrid-Maize model. preferred with the consideration of shortage of available water resource in the area. Similarly, the practice we choose were benefit for enhancing the photosynthesis assimilation capacity at the grain filling stage and prolonging the importent stage.