Abstract: In order to reveal the feasibility of increasing and maintaining yield with green agriculture development by using multiple spike cultivar to enhance density based on decreasing nitrogen application rate, we studied the effects of the interaction of four nitrogen fertilization levels and three planting density on root traits, photosynthesis, grain quality and yield of wheat. Under the same nitrogen level, the length, surface area, average diameter of root were insignificantly affected by planting density, while root volume and root tips were significantly affected by planting density, the root length, root surface area, root volume and root tips of N1 (traditional N application amount)were significant higher than that of N3 (70% N1)under the same planting density. Under the same planting density, the flag leaf area was not significantly reduced at booting stage when decreasing 15% nitrogen (N2, 85% traditional N application amount)application amount, while was significantly reduced by decreasing 30% N application amount. Chlorophyll content was not significantly affected by planting density, the chlorophyll content of N1 was significantly higher than that of N3 under the density of D1 (180×10⁴ plants/ha)and D3 (360×10⁴ plants/ha). Under the same nitrogen level, to increase planting density would led to photosynthetic rate, stomatal conductance and transpiration rate increased and intercellular CO₂ concentration decreased, when compared to N3, N1 significantly increased photosynthetic rate and stomatal conductance by 20.03%, 18.44%, 17.36% and 24.11%, 20.40%, 19.76% under D1, D2 (270×10⁴ plants/ha), D3. The grain protein, starch, wet gluten and sedimentation value was insignificantly affected by density, the difference in protein content and sedimentation value between N1 and N3 was significant, while in starch and wet gluten content were in significant. Under the same nitrogen level, to increase the density of 180×10⁴ plants/ha basic seedlings could significantly enhance the population dry matter weight of wheat at each stages, the population dry matter weight was significantly decreased when N application amount reduced from N1 to N3, the biological yield of N2D3 and N3D3 were higher than or equal to N1D1 and N1D2, and the biological yield of N3D3 was higher than or equal to N2D1 and N2D2. Compared to D1, under N1, N2, N3, D3 increased the yield by 11.83%, 11.42%, 14.03% and 5.52%, 10.31%, 10.88% respectively in 2016 and 2017, the yield of N3D2 and N3D3 were higher than or equal to N1D1. All the findings showed that when to reduce 15%-30% N and increase the density of 90×10⁴-180×10⁴ plants/ha basic seedlings could lead to biological and economic yield higher than or equal to that of the treatment without N reduction.

Key words: Root traits, Flag leaf area, Photosynthesis, Grain quality

CLC Number: 

• S512.01

• S141.1