Table II.

Effects of localized NPA application at the root-shoot junction on free IAA concentration

TreatmentFree IAA Concentration1-aLateral Root No.1-b
ng/g fresh wt
Control agar25.8  ± 4.715.5  ± 0.8
NPA agar17.6  ± 2.25.9  ± 0.5

Seven- or 8-d-old seedlings were treated by application of agar with or without NPA to the root-shoot junction. After 3 additional d of growth, roots were harvested and the free IAA concentration was determined by GC-SIM-MS or the number of lateral roots was determined.

    • F1-a The reduction in free IAA concentration was statistically significant using a Mann-Whitney U test (P = 0.04).

    • F1-b The reduction in lateral root number was statistically significant using Student's t test (P ≤ 0.001).