Analysis of maize root traits in response to low nitrogen

Abiotic stress such as low nitrogen content present in the soil is responsible for reduced yields throughout the world. Plant breeders aim to develop plants that can adapt to such environments. There is a need for more efficient root systems tolerant to an array of abiotic stresses. The objective of this study was to assess the root systems of 10 maize intermated B73-Mo17 (IBM) genotypes and their parents B73 and Mo17 for their growth and morphology and their response to low nitrogen. The aim was to test the hypothesis that published QTL regions related to root traits and nitrogen use efficiency could be used to select recombinant inbred lines (RILs) that would differ in their response to nitrogen stress based on which parental background predominated at these QTL regions. Ten IBM genotypes from the published Maize Genome Database were evaluated in this study along with their parents B73 and Mo17. Five IBM genotypes were chosen that carry predominantly B73 alleles at five quantitative trait loci (QTL) regions associated with root traits and nitrogen use efficiency and five genotypes were chosen that carried predominantly Mo17 alleles in these regions. Plants were grown in Guterman Green House of Cornell University, USA. Two nitrogen treatments (low and high) were given to note the effect of different nitrogen levels. Plants were grown and nitrogen stress symptoms were observed over time. Various root traits like root length, branching, adventitious roots, lateral roots, primary root length, and root dry weight were observed. Results showed that nitrogen treatment variation was significant for all traits measured except root length and numbers of adventitious, lateral, and primary roots. Genotype by nitrogen treatment interaction was significant for root dry weight. At high nitrogen, IBM189 showed the highest value of root dry weight and IBM337 had the lowest value. Based on the root dry weight under low nitrogen condition, the genotypes were classified into three categories: susceptible, moderate and resistant. Significant groupings from the most susceptible to most resistant were: Mo17, IBM337, IBM189, IBM248, IBM280=IBM153, IBM055=B73, IBM346, IBM284, IBM236, IBM056. A relationship between root length and nitrogen stress resistance was not found in this study. Genotype with high in B73 composition had relative advantage over Mo17 in dry weight of roots under low nitrogen condition. It is relatively difficult to measure the effect of nitrogen levels on various root traits.

Author(s): Sumita Sen*, Margaret E. Smith and Timothy L. Setter

Abstract | PDF

Share This Article