Abstract: 【Objective】A field study on dryland spring maize in three treatments was conducted to explore the source-sink relationship between nitrogen accumulation and dry matter transfer in different mulching treatments on the Changwu Tableland of the Loess Plateau in northwest China. 【Method】The light energy capture and soil temperature in treatments of plastic film mulching, gravel mulching, and no mulching (CK) were observed, and dry matter accumulation and nitrogen accumulation were analyzed through two years.【Result】The effective accumulated temperature of the plastic film mulching was significantly higher than that of the CK treatment, but no significant differences compared with gravel mulching treatment. The radiation utilization efficiency of the plastic film mulching treatment was significantly higher than that of the other treatments. The accumulated temperature production efficiency of plastic film mulching treatment was significantly higher than that of other treatments, the difference of its radiation production efficiency with other treatments was not obvious in 2010, and however, its radiation production efficiency was significantly higher than that of CK treatment and lower than that of gravel mulching treatment in 2011. The dry matter transfer amount of stem and leaf sheath reached the maximum. The contribution rate of soil surface mulching to dry matter transfer and its impacts on dry matter transfer rate were not significant. At reproductive growth stage, the single grain weight of corn grain increased with growth of corn. However, the number of single grain decreased instead. Under the condition of plastic film mulching, the weight and number of single grain in harvest time were higher than that in other treatments. Within 30 days after silking, the average nitrogen content of corn grain in plastic film mulching was significantly higher than that in gravel mulching and CK treatments; within 30 days after grain filling and up to mature period, the difference of nitrogen content in corn grains was not significant and the nitrogen content in plastic film mulching treatment was slightly higher than that in gravel mulching and CK treatments. As the difference in dry weight of corn grains, the nitrogen accumulation amount in plastic film mulching was significantly higher than that in grave mulching and CK treatments. The mulching treatment had effectively increased the nitrogen accumulation of grains in upper, middle and lower parts of corn ear; the nitrogen accumulation amount of grains in each parts of corn ear in plastic film mulching treatment was significantly higher than that in gravel and CK treatments. The dry matter transfer amount and contribution rate to dry matter transfer were positively related to the volume and weight of single grain and effective accumulated temperature, which reached at a significant level; however, although the dry matter transfer amount and contribution rate to dry matter transfer were positively related to the number of single grain, the fractional interception of photosynthesis active radiation and production efficiency of accumulated temperature and radiation, it did not reach at a significant level. The plastic film mulching increased the dry matter accumulation capacity based on the number of single grains, and dry weight of ear grain to facilitate nitrogen accumulation of corn grains, improve the nitrogen use efficiency and increase production.【Conclusion】The plastic mulching promoted the accumulation of nitrogen and improved the utilization efficiency of nitrogen, thus improved the yield of maize on the Loess Plateau.

Key words: soil surface mulching, soil temperature, photosynthesis active radiation, dry matter accumulation and transfer, nitrogen accumulation, maize