Effects Of Interaction Between Silicon And Nitrogen On Biological And Photosynthetic Characteristics Of Echinochloa Crusglli (L.)Beauv.Var.Oryzicola

Echinochloa crusglli?L.?Beauv.var.oryzicola is an annual grass plant,which is a kind of Echinochloa crusglli?L.?Beauv.var.oryzicola.Its living habits are very similar to rice.Once it appears in rice field,it is difficult to be removed.Nitrogen and silicon are two important nutrient elements for plant growth.They have an impact on plant growth and yield formation.At present,silicon-nitrogen interaction on crops are rarely,however,there are few studies on the effect of silicon-nitrogen interaction on weeds in rice field.In this experiment,four silicon-concentrations?calculated by SiO₂?,Si₀:0kg·hm^-2,Si₁:46.7kg·hm^-2,Si₂:93.3kg·hm^-2,Si₃:140kg·hm^-2 were set;four nitrogen concentrations?in pure quantity?,N0: 0kg·hm^-2,N₁: 112.5kg·hm^-2,N₂: 225kg·hm^-2,N₃: 337.5kg·hm^-2;because of the applied silicon fertilizer contains Na⁺,in order to eliminate the interference of salt,four sodium sulfate treatments were set as comparative experiments,S₀:0kg·hm^-2,S₁:356kg·hm^-2,S₂:563.5kg·hm^-2,S₃:771kg·hm^-2.were used to study the effects of silicon-nitrogen interaction on the growth and development of Echinochloa crusglli?L.?Beauv.var.oryzicola.The effects of silicon-nitrogen interaction on the growth and development of Echinochloa crusglli?L.?Beauv.var.oryzicola were studied by measuring plant height,tiller number,spatial distribution,photosynthetic index and biomass during seed setting.The main studies were as follows:?1?The interaction of silicon and nitrogen had a significant effect on plant height and number of tillers in tillering and full-blooming stages.The plant height and number of tillers of Echinochloa crusglli?L.?Beauv.var.oryzicola increased from tillering stage to full-blooming stage.The interaction of silicon?Si₂?with nitrogen?N₂,N₃?at medium and high concentrations significantly promoted the plant height of Echinochloa crusglli?L.?Beauv.var.oryzicola.The interaction of high concentration silicon?Si₃?and high concentration nitrogen?N₃?promoted the growth and development of Echinochloa crusglli?L.?Beauv.var.oryzicola.?2?Under different concentrations of silicon and nitrogen,the tiller angle of Echinochloa crusglli?L.?Beauv.var.oryzicola decreased with time;in tillering stage,the plant structure of Echinochloa crusglli?L.?Beauv.var.oryzicola was the most compact under the interaction of medium concentration silicon?Si₂?and low concentration nitrogen?N₁?;in jointing stage and full-blooming stage,the plant structure of Echinochloa crusglli?L.?Beauv.var.oryzicola was the most compact under the interaction of low concentration silicon?Si₁?and low concentration nitrogen?N₁?;with the growth and development of Echinochloa crusglli?L.?Beauv.var.oryzicola,the tiller position of Echinochloa crusglli?L.?Beauv.var.oryzicola decreased in the positive West,and increased in the positive East and positive north;the distribution of tillers in all directions of tillering stage was relatively average,and in jointing and full-blooming stage,the tiller distribution was relatively similar.?3?From tillering stage to full-blooming stage,the intercellular CO₂ concentration of Echinochloa crusglli?L.?Beauv.var.oryzicola increased,while the net photosynthetic rate,transpiration rate and stomatal conductance decreased;The interaction of low silicon?Si₁?and low nitrogen?N₁?inhibited the intercellular CO₂ concentration,stomatal conductance and transpiration rate of Echinochloa crusglli?L.?Beauv.var.oryzicola.The interaction of high silicon?Si₃?and high nitrogen?N₃?promoted the intercellular CO₂ concentration,net photosynthetic rate,stomatal conductance and transpiration rate of Echinochloa crusglli?L.?Beauv.var.oryzicola.?4?The interaction of silicon and nitrogen had no significant effect on the biomass of Echinochloa crusglli?L.?Beauv.var.oryzicola leaves,but had significant effect on the remaining organs;under the interaction of high concentration silicon?Si₃?and high concentration nitrogen?N₃?,the biomass of each organ of Echinochloa crusglli?L.?Beauv.var.oryzicola reached the maximum;the biomass reproductive allocation of Echinochloa crusglli?L.?Beauv.var.oryzicola was the highest under the interaction of low silicon and high nitrogen?Si₁N₃?.At a certain nitrogen concentration,the biomass reproductive allocation of Echinochloa crusglli?L.?Beauv.var.oryzicola leaves,leaf sheaths and ears reached the maximum value at Si₃ concentration;the biomass reproductive distribution of Echinochloa crusglli?L.?Beauv.var.oryzicola was the highest at the concentration of Si₂;the effect of Si-N interaction on roots is significant.?5?The interaction of high concentration silicon?Si₃?and high concentration nitrogen?N₃?promoted the growth,development and biomass accumulation of Echinochloa crusglli?L.?Beauv.var.oryzicola;the interaction of low silicon?Si₁?and low nitrogen?N₁?inhibited the photosynthesis of Echinochloa crusglli?L.?Beauv.var.oryzicola,and the plant structure of Echinochloa crusglli?L.?Beauv.var.oryzicola was the most compact under this treatment.