Yale University

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were about 3 cm high on Dec 29th they were transplanted to 9.5 x 9.5 x 8 an pots containing a mixture of 2:2:1:1 peat moss, top soil, vermiculite and
perlite respectively. A prototype biostimulant containing marine algae
extracts, humic acids, and an intermediate metabolite (calk..? Metab), was obtained from Soilizer Corp., 25 Science Park, New Haven, CT 06511. The pH
was adjusted to 5.5 before application to the potted plants.
The main treatments were a Control (treated weekly with tap water at
pH 5.5) and another set of plants treated weekly with the OB. In prelitrtinary experiments we found that all three ingredients actively promoted plant growth. The pots were treated to saturation, ca. 60 ml per pot. In addition to.
the weeldy treatments all pots were watered twice more per week with tap water so that there was a total of three waterings per week per pot. At each watering the pots were rotated to avoid any possible location effects. The plants were fertilized once every two months with an all purpose plant food (15:30:15) at a concentration of 35 g per gallon of water. At 9 months fertilization was stopped and for the last six months the plants received only water (control) or water and OB (treated plants). Temperature varied from about 20 C in winter to 30 C in summer. Light conditions were ambient and had a midday maximum of ca. 1200 j~iMnr2sec1 photosynthetic photon flux density (PPFD). On March 13, 1989 the eighteen plants were harvested and the following attributes were measured: height of stem, diameter at ground line (just above the root collar), fresh and dry weight of stem and needles. The plants were pot bound and roots had been trimmed off the bottom of the pots several times during the preceding 15 months so no measurements were not made on the roots although this property was measured in a number of previous experiments. In general the biostimulant promotes the growth of all plant organs induding roots, however, in the preliminary experiments there was little effect on the root shoot ratio (see Table 1).
At harvest the following properties were measured: stem height, basal diameter, fresh weight of needles, fresh weight of stem. The tissues were then oven-dried at 75-80 C until constant weight was obtained (approximately two weeks) and then needle and stem dry weights were obtained for each tree. Basal area was calculated from the area of circle at ground line and density was calculated as stem mass divided by stem volume (see Anoruo 1988 for details).