Diffreences Of Nitrogen Absorption Kinetics And Physiological Traits Among Rapeseed Of Varied Nitrogen Uptake Efficiency

Some domestic and abroad researches showed significant genotypic differences in rapeseed nitrogen efficiency. Nitrogen efficiency could be divided into nitrogen uptake efficiency and nitrogen utilization efficiency. Nitrogen uptake efficiency is related to the ability of uptaking nitrogen of the soil, and nitrogen utilization efficiency characterizes plant assimilation and utilization of nitrogen. Nitrogen uptake efficiency is an important part of nitrogen efficiency. In order to exploit the genetic potential of nitrogen absorption in rapeseed and increase the yield potential of nitrogen fertilizer in rapeseed, in this study, the differences of genotypes with different nitrogen uptake efficiency of rapeseed were analyzed. Plant nitrogen uptake was measured among 50 different genotypes of rapeseed under pot and field conditions. On the basis of this measurement, the genotypes with varied nitrogen uptake efficiency were selected, N-responder, N-noresponder, N-efficient, N-inefficient genotypes were obtained. The four genotypes were used in a hydroponic culture experiment to determine the differences of nitrogen uptake and physiological characteristic during the early stage of seedling. nitrogen content, biomass, nitrogen uptake, net photosynthetic rate, SPAD value, nitrate reductase activity and root activity of different genotypes were measured. The results show that N-responder and N-efficient genotypes had significant higher nitrogen content of roots than that of N-nonresponder and N-inefficient genotypes in high nitrogen(6 mmol/L) and low nitrogen tendency(0.6 mmol/L), respectively. However, there was no significant difference of aboveground nitrogen content, aboveground biomass, net photosynthetic rate of leaves, and SPAD value. This indicates that N-responder and N-efficient genotypes can uptake more nitrogen in roots than that of N-nonresponder and N-inefficient genotypes during the early stage of rapeseed seedling while they don’t transport more nitrogen to aboveground parts in this period. Further study is needed to find the differences of aboveground parts between different genotypes. And nitrogen uptake kinetics parameters had no significant between the inefficient genotypes and efficient genotypes. In summary, the genotypes with varied nitrogen uptake efficiency did exist differences in the seedling stage. However, the differences only showed in the root nitrogen content and nitrogen uptake. The absorption kinetics and other physiological indicators need to be further studied in other stages of oilseed rape.