Genotypic difference in root traits and its relationship to nitrate uptake in maize inbred lines

摘要

An experiment was conducted under environmentally controlled conditions to evaluate the genotypic difference of root morphology and the relation to N uptake. Three maize inbred lines (478,Wu312, Zong31)that differed in N efficiency in three year's field test were used at three nitrate levels(0.04,0.4, 4 mmol/L)by the method of solution culture in seedling period. It was found that 478, a N efficient variety, accumulated a larger amount N in comparison with N inefficient lines(Wu312, Zong31) at N supply levels. At low nitrate concentration (0.04 mmol/L),A high N accumulation for 478 was mainly contributed by the largest root biomass which was 0.74,0.6 times larger than Wu312 and Zong31 respectively, it also showed that the genotypic difference of root dry weight among the three varieties was more significant than that of shoot. Large root biomass for 478 was due to its longer root length especially for length of root axis but not for laterals compared with the other two varieties. When nitrate concentration increased form 0.04 to 0.4 mmo/L, root biomass was enhanced to various degree, whereas it could inhibit root growth and shoot growth had a priority to root at high nitrate level(4 mmo/L),in this case, the root of 478 was the most responded variety to nitrate, and took up more N in the test lines therefore, longer laterals were one of the main factors influencing high N uptake for 478 at high N supply.