5-gal bucket of the appropriate root-dip mixture. The 

 excess material was allowed to drip off the roots. Then 

 the seedlings were placed on a piece of wet bvtrlap and 

 rolled into a jellyroU to protect the roots during accli- 

 matization and planting. Jellyrolling is a process in 

 which the seedlings are distributed with their roots 

 on a piece of wet burlap. The burlap is rolled sideways 

 like a carpet so that the shoots stick out the top and 

 the roots are protected inside. Seedlings were accli- 

 matized at 40 to 45 °F for 18 hours. 



Seedlings were transported to the study sites in the 

 morning just before planting. To prevent imnecessary 

 exposure, each seedling went directly from the wet 

 burlap of the planting bag into the planting hole. Each 

 tree planter planted an equal number of all treatments. 



Field Test 1— The objective in the first field test 

 was to determine the effects of three different root dips 

 on survival and growth of lodgepole pine in a soil of 

 basaltic origin. Ten blocks were placed in one continu- 

 ous study plot on the Ashton Ranger District of the 

 Targhee National Forest with a silt-loam soil of basal- 

 tic origin. Seedlings were planted on June 8, 1983. 

 The site had a northeasterly aspect with less than 

 a 10 percent slope at 5,900 ft elevation. The habitat 

 type was Douglas-fir/pine grass (Pseudotsuga men- 

 ziesii I Calamagrostis rubescens) (Steele and others 

 1983). 



Seedlings were stored in a snow cache at 32 °F 

 before planting. The site was prepared for planting 

 using an SFI mechanical scalper. Each block con- 

 sisted of four 12-tree rows. Each row contained one 

 of the root-dip treatments: vermiculite; vermiculite 

 slurry; Terra Sorb®, a commercially produced hydro- 

 philic gel; or a control treatment in which seedlings 

 were dipped in water. Treatment rows were ran- 

 domly arranged in each block. After 35 days of growth, 

 one tree from each row was excavated to measure 

 new root growth. Six weeks afler planting, the seed- 

 lings were released from grass competition by apply- 

 ing Roundup® herbicide in a 4- by 4-ft area around 

 each tree. 



Field Test 2— The objective of the second test was 

 to determine the effects of three different root dips on 

 survival and growth of ponderosa pine on a soil of gra- 

 nitic origin in the Boise National Forest. The treat- 

 ments were similar to those in the first field test except 

 that Aquagel®, another commercially available hydro- 

 phihc gel, was tested instead of Terra Sorb®. Planting 

 stock was stored in a cooler at 34 °F before planting 

 on the Idaho City Ranger District in April 1988. 



The habitat type was Douglas-fir/ninebark {Pseu- 

 dotsuga menziesii/Physocarpus malvaceus) (Steele 

 and others 1981). The study site straddled a draw. 

 Three blocks, facing southwest, were placed on one 

 side of the draw. Seven blocks faced east. Average 

 slope was 35 percent; the elevation was 5,400 feet. 



The trees were planted on 2- by 2-ft hand scalps con- 

 structed just before the holes were augered. Four 

 different treatment rows were randomly arranged in 

 each block, as in the first field test. Forty-two days 

 after planting, one tree from each row was excavated 

 and its root growth was measured. 



Analysis 



Each experiment was set up in a randomized block 

 design. Data were analyzed using analysis of variance 

 tables at a 95 percent level of confidence. Differences 

 between means were determined using Duncan's 

 range test, again at a 95 percent level of confidence. 



Results 



We found that results differed with species, type of 

 root dip, and soil texture. The re8\ilts are summarized 

 for growth chamber experiments, greenhouse experi- 

 ments, and field studies. 



Growth Chamber Studies 



In early growth chamber studies we tested only 

 lodgepole pine seedlings potted in a medium conducive 

 to root growth. We looked at the effects of only one 

 root-dip substance, vermiculite slurry. Under these 

 conditions vermiculite slurry root-dip treatments had 

 little effect on the mean length of the new roots, but it 

 decreased the number of new roots longer than 1.5 cm 

 by about one-half. That meant the total length of new 

 roots per seedling was less. The mean nimiber of new 

 roots shorter than 1.5 cm and terminal shoot growth 

 were similar for dipped and undipped seedlings 

 (table 1). 



In the next growth chamber experiment, we ex- 

 panded the methods to include four different potting 

 media. Because of limited growth chamber space, we 

 again tested only lodgepole pine. 



Seedlings potted in the sandy granitic soil produced 

 shorter roots on average than the other soils. Total 

 numbers of new roots were similar for all four soils. 

 The vermiculite slurry root dip reduced the number 

 of new roots shorter than 1.5 cm, the total length of 

 new long roots longer than 1.5 cm, and the summed 

 length of all new roots (table 2). 



Neither soil nor root-dip treatments caused differ- 

 ences in plant water potential, number of mycorrhizal 

 root tips, or shoot elongation (a = 0.05). 



Greenhouse Studies 



In the first greenhouse experiment, the vermiculite 

 slurry root-dip treatment reduced the number of short 

 roots and the total length of new roots. Vermiculite 

 slurry was detrimental to the growth of long roots for 



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