| The furrow and ridge film mulching planting system (FRFM) have been regarded as effective approaches to conserve soil water and increase crop yield in dryland area. But the relationship of winter wheat individual-population restrict the yield improvement. The experiment was conducted in field by the binary quadric orthogonal rotational combination design, to research the effects of planting density and N rate on relationships of winter wheat individual and its plant population, and the effect of relationship on grain yield under ridge film mulch planting system. The tested cultivar is Xiaoyan22. The field trials were conducted from Oct. 2008 to Jun. 2009 at the Agricultural Experimental Station of Northwest A&F University, Yangling, Shaanxi province. It is a sub-humid area susceptible to drought, and located in the southern loess plateau, the soil is classified as Eum-Orthic Anthrosol. The main results obtained from the experiments are as follows:1. In this study, the basic seedling, tiller number before winter, total tiller number and the population size all increased with increasing planting density in FRFM. High-density and low N rate co-operation were benefit to tiller before winter, and low-density and high N rate coupling was benefit to spring tillers. It was increased of the number of head per unit area and the rate of heading by appropriate N rate. The yield increase of individual plant could compensate the yield lose owing to heads deficits per unit of lower density in some under the ridge planting system. Both planting density and N fertilizer had pronounced effects on the grain yield under the experiment, and the effect of N fertilizer was more significant than that of planting density. The optimum yield would be obtained with the application of nitrogen 202~227kg N/ha and density 98~127kg/ha, while the highest yield of 3851.68 kg/ha with coupling of planting density (101.75kg/ha) and N rate (222.71kgN/ha). Compared with conventional cultivation, it could increase the yield per unit area of FRFM with optimum population owing to higher yield of individual plant. In order to increase the yield of winter wheat, it was very important to coordinate the relationship of individual winter wheat and its population with the coupling of planting density and N rate.2. Results showed that the photosynthetic rate, SPAD value and LAI of wheat were obviously declined and the intercellular CO2 concentration, transpiration rate and stomatal conductance were increased during the grain filling. SPAD value and leaf area index (LAI) in FRFM were significantly higher than those of conventional cultivation in middle of grain filling. Maximum LAI of conventional cultivation was in the early filling stage, while FRFM appeared in the middle filling stage. The reasonable planting density and N rate adjusted the tiller and head number to affect the growth of winter wheat. Under D2F4 (seeding rate: 85.95kg/ hm~2, N rate: 135.57kg N/hm~2) treatment, the wheat flag leaf photosynthesis, SPAD value and LAI were all at a high level, and it's yield was 4009kg/hm~2, was higher than that of other treatments.3. Under the conditions of the tests, low density (78.10 ~ 105.95kg/hm~2) was benefit to the dry matter accumulation of winter wheat individual; low N rate (158.67~185.80 kg N/hm~2) could promote the growth of wheat individual at anthesis. High N rate(200.74~210.56 kgN/hm~2) could increase of the shoot dry matter accumulation during anthesis and maturity stage.4. N fertilization increased N accumulation and mobilization amount at anthesis and maturity stage. There were more N accumulation and mobilization in wheat individual of FRFM than that of conventional cultivation, but the N accumulation and mobilization in wheat population were lower than that of conventional cultivation. High density (109.42 ~ 120.71 kg/hm~2) was benefit to the N accumulation of winter wheat individual and populatiin at anthesis, but its harm for N accumulation at maturity stage. N rate was higher than D3(180kgN/hm~2)treatment could promote the N accumulation of wheat individual and populatiin at anthesis and maturity stage.5. The relationship of winter wheat individual plant - population could regulate and control the relationship of P accumulation and mobilization. To improve the number of head per unit area was important to P accumulation and mobilization of winter wheat individual plant– population. N fertilization and FRFM could promote the P accumulation and mobilization . The D2F4 treatment was benfit to P accumulation and mobilization in all treatments.
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