Effects of Leaf Nitrogen Allocation on Photosynthetic Nitrogen Use Efficiency in Shaded Soybean Seedlings
[Objective]This study aims to elucidate the relationship between photosynthetic characteris-tics and nitrogen distribution in soybean leaves at the seedling stage,thereby providing a theoretical foun-dation for the rational allocation of nitrogen nutrition,enhancement of photosynthetic nitrogen use effi-ciency,and the promotion of high-yield soybean cultivation.[Method]Two soybean varieties with con-trasting shade tolerances were utilized as experimental subjects,and five nitrogen application levels were established to assess the photosynthetic characteristics of soybean under varying shade and nitrogen appli-cation conditions,as well as their correlation with nitrogen allocation.[Result]Appropriate nitrogen ap-plication enhanced the photosynthetic rate,pigment content,and fluorescence characteristics of soybean under shade conditions.The nitrogen distribution within the carboxylating and bioenergetic systems sig-nificantly increased with rising nitrogen application levels,whereas the proportion of nitrogen distribu-tion in the light harvesting systems remained unchanged,and the nitrogen allocation in non-photosynthetic structures exhibited a gradual decrease.Photosynthetic nitrogen use efficiency(PNUE)and net photosynthetic rate(Pn)were positively correlated with nitrogen allocation in the carboxylating and bioenergetic systems,but showed a weak correlation with nitrogen allocation in the photoharvesting systems.[Conclusion]The key to improve the nitrogen use efficiency at seedling stage of soybean lies in nitrogen allocation in carboxylation and bioenergetics systems,and has little relationship with nitrogen al-location in light harvesting systems.At the same time,varieties with strong shade tolerance can better co-ordinate nitrogen distribution in the photosynthetic system and improve photosynthetic capacity.
万方数据
维普
