Abstract: To explore suitable nitrogen fertilizer and planting density of rice under water saving irrigation in the double cropping rice area of Hunan, a split-plot experimental with the nitrogen treatment as amount area and planting density as subplot was designed, to explore the effects of different nitrogen and density to the matter production characteristics of double cropping late rice cultivar Fengyuanyou 299. The results showed that:Rice yield increased with the increase of biomass, they were extremely significantly correlated in the late growth stage of rice; while the application of nitrogen promoted the biomass to some extent, high planting density also significantly enhance the biomass, generally low density nitrogen treatment got the highest biomass. Photosynthetic potential played a positive role in the formation of rice economic product, and photosynthetic potential increased with the planting density and nitrogen application rate on the rise, the effects of net assimilation rate to rice yield was not obvious. In terms of assimilation transport, economic yield of rice and dry matter accumulation after heading were significantly positively related, with the export amount of the matter in stem and leaves, export percentage of the matter in stem and leaves, transformation percentage of the matter in stem and sheaths, export percentage of the matter in stem and sheaths correlation were not correlated, the overall amount of dry matter accumulation after heading increased with the rising of nitrogen and planting density, the dry matter accumulation was most abundant under the treatment of low nitrogen and high density. Rice yield increased with the rising of leaf area index, while the level of nitrogen fertilizer, planting density showed a significant positive impact to leaf area index. Rice yield and chlorophyll content had no direct correlation, chlorophyll content increased with the increase of nitrogen fertilizer, planting density had no direct influence on chlorophyll content. Rice yield and root activity were positively correlated, the application of nitrogen significantly increased pre-root activity, but later no significant effect, high planting density helped improve root activity. So, it was very important to build appropriate rice population for high-yield rice, our study demonstrated that the optimum low nitrogen level and high planting density could help to form an efficient high-yield rice population structure, thus contributing to the increase of production.

Key words: Water saving irrigation, Interaction of nitrogen and density, Biomass, Net assimilation rate, Chlorophyll content, Root activity

CLC Number: 

• S143.1

• S511.3+3