Fracheboud, Y., Hund, A., Ruta, N., Liedgens, M., Stamp, P.
Genetic variation in root morphology and its response to water deficit might be crucial for the adaptation of maize (Zea mays L.) to drought, but information about this is scarce. A set of 208 recombinant inbred lines (RILs) from the cross between Ac7643 (Parent 1) and Ac7729/TZSRW (Parent 2) was investigated in growth pouches to determine the traits of seedling roots and shoots. Water stress was induced by polyethylene glycol (PEG 8000). Quantitative trait loci (QTLs) were identified for seedling traits at the first leaf stage; their collocation was compared with published yield-related traits found in drought-stress experiments. Some seedling QTLs were specific to water stress, such as QTLs for root dry weight, shoot dry weight, and leaf area-to-root length ratio. Four root and shoot QTLs collocated in bin 2.02, indicating a relationship of this chromosome region to early vigor under water stress. Quantitative trait loci for ear number collocated with QTLs for the shoot-to-root dry weight ratio and leaf area-to-root length ratio. Quantitative trait loci for the anthesis-silking interval collocated with QTLs for the numbers of crown roots and seminal roots irrespective of water supply. Quantitative trait loci controlling the balance between early root and shoot development may provide useful information to enable the prediction of maize performance under field conditions.