Table IV.

Effects of application of NPA to the upper and lower halves of seedling roots

Agar	Lateral Root No.	Lateral Root Densitya	Change in Lengthb
			mm
Controlc	4.4  ± 0.6	0.46  ± 0.07
Controld	5.3  ± 1.1	0.14  ± 0.03	30.2  ± 1.0
NPAc	1.7  ± 0.5	0.18  ± 0.05e
Controld	0.1  ± 0.1	0.00  ± 0.00e	23.5  ± 1.0
Controlc	4.4  ± 0.5	0.49  ± 0.06
NPAd	1.3  ± 0.6	0.05  ± 0.02e	12.1  ± 0.7

Six-day-old seedlings were transferred to plates containing 10 μm NPA in the upper or lower half, as indicated. After 4 additional d of growth in the light, lateral roots in the upper and lower halves were counted and new primary root growth was measured. The reported values are averages ± se of 10 plants.

^aThe 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. 

^bThe amount of elongation of the primary root after transfer to the indicated plates. 

^cThe compound in agar and the lateral root growth on the upper half of the plate is shown. 

^dThe compound in agar and the lateral root growth on the lower half of the plate is shown. 

^eLateral root density decreased significantly (P ≤ 0.002) as judged by Student's t test.