Treatments : Two weeks after transplanting, the following treatments were applied once a week to 20 pots of each species (assigned at random): a) Control (blue tags); b) ROOTS 0.5%, 10 ml solution per pot (orange tags). This means 1 ml of the commercial product/plant/20 weeks; c) ROOTS 1.0%, 10 ml solution per pot (green tags). This means 2 ml of the commercial product/plant/20 weeks.

The pots were watered three times a week. Temperature in the greenhouse was always at or above 15 C. through thermostatic control. Maximum temperatures were 29 C~ No filters present to remove ozone, sulfur oxides or other pollutants from the air.

After 20 weeks, all plants were harvested. Total height and root length were measured. Shoot and root fresh were determined with a Mettler P1200 balance in the greenhouse. Root samples were taken and preserved in FAA for mycorrhizal infection assessment. Samples were dried in Blue H Electric Co. over (Blue Island, Illinois) for 96 hours at 70-74 C. and then dry weights were determined on a precision balance (Mettler H3l).

Data were analyzed for analysis of variance with EPISTAT, a statistical package for small set of data designed by T.L. Gustafson, Round Rock, Texas.

RESULTS

Loblolly Pine

After twenty weeks of treatment, root fresh weight showed significant differences (P<0.0l) between the control and all the ROOTS treatments (Figure 1). The 1.0% treatment was 63% higher than the control.

Significant differences (P<0.01) in shoot fresh weight were observed between the control and 0.5% and 1.0% treatments. The 1.0% treatment was 33% higher than the control.

Dry weight values showed a similar behavior although with some variation. Root dry weight showed differences (P=0.015) between the control and the 0.5% and 1.0% ROOTS treatments, which were higher. The 1.0% treatment was 43% higher than the control.

Shoot dry weight, unlike fresh weight, showed no statistical

differences at conventional level of confidence. However the

1.0% treatment was 33% higher than the control. Root dry weight

showed differences (P=0.015) between the control and the 0.5% and

1.0% ROOTS treatments, which were higher. The 1.0% treatment was

43% higher than the control.

The differences in growth became evident after 84 days (12 weeks) of treatment when statistically significant differences in total height between the 1% ROOTS treatment and the control were detected.