Table I.

Effects of localized NPA application on lateral root development and root length

[NPA]Lateral Root No.Root LengthLateral Root Density-a
μm mm
0.015.9  ± 1.048.6  ± 1.40.33  ± 0.02
5.012.3  ± 0.847.2  ± 0.70.26  ± 0.02-b
10.010.4  ± 1.145.9  ± 1.10.23  ± 0.02-b
20.08.6  ± 0.739.0  ± 1.70.22  ± 0.20-b
50.06.4  ± 0.645.0  ± 0.90.14  ± 0.02-b
100.01.0  ± 0.338.7  ± 1.70.03  ± 0.00-b

Four-day-old seedlings were treated by application of agar containing NPA at the indicated concentrations to the root-shoot junction. After 6 additional d of growth, lateral roots were counted and the length of the primary roots was measured. The reported values are averages ± se of 10 plants.

    • F0-a The lateral root density was calculated by dividing the number of lateral roots by the primary root length for each plant, and is reported as the number of lateral roots per millimeter of primary root. The average ± se of the lateral root density calculated for each root is reported.

    • F0-b Lateral root density was significantly reduced by all concentrations of NPA (P ≤ 0.007).