1,400-1 



Ponderosa pine Douglas-fir 



Figure 4 — Average total length of roots 

 longer than 1 .5 cm from 96 ponderosa 

 pine and Douglas-fir seedlings grown in 

 the greenhouse for 30 days (greenhouse 

 experiment 1). Seedlings were root 

 dipped in a vermiculite slurry or were not 

 dipped before being potted in one of three 

 soils. 



Basalt Granite Peat-vermiculite 



Parent Soil Material 



Figure 5 — Average number of roots longer 

 than 1.5 cm from 300 lodgepole pine, ponde- 

 rosa pine, Douglas-fir, and Engelmann spruce 

 seedlings grown in the greenhouse for 30 days 

 (greenhouse experiment 2). Seedlings were 

 dipped in one of four root dips: vermiculite, 

 V2X vermiculite slurry, 1 x vermiculite slurry, 

 2x vermiculite slurry, or were not dipped before 

 being potted in one of three soils: basaltic, gra- 

 nitic, or peat-vermiculite-sandy loam. 



Table 4 — Summary of data from 300 seedlings grown in the greenhouse for 30 days (greenhouse experiment 2). Four species 

 were treated with one of five root dips before being potted in one of three soil types. Mean values in each group 

 followed by the same letter are not significantly different (a = 0.05) 









Plant 



Roots^^ 



Length^'2 





Mycorrhrizal 







Leader 



water 



of roots 



Roots' 



root tips per 



Treatment 



Seedlings 



growth 



potential 



>1.5 cm 



>1.5 cm 



<1.5 cm 



10-cm sample 





No. 



cm 



MPa 



No. 



cm 





-No. 



Species 

















Lodgepole pine 



75 



9.8 c 



-0.75 a 



43 c 



222 d 



318 c 



51 c 



Ponderosa pine 



75 



6.7 b 



-0.77 a 



22 b 



97 c 



176 b 



51 e 



Douglas-fir 



75 



2.2 a 



-1.34 b 



4a 



14a 



40 a 



6 a 



Engelmann spruce 



75 



1.9 a 



-0.81 a 



18 b 



56 b 



264 c 



32 b 



Soil type 

















Basalt 



100 



4.6 a 



-1.02 b 



6 a 



17 a 



123 a 



25 a 



Granite 



100 



5.4 b 



-0.90 a 



21 b 



79 b 



221 b 



44 b 



Peat-vermiculite 



100 



5.5 b 



-0.84 a 



40 c 



195 c 



254 b 



34 ab 



Root dip 

















Not dipped 



60 



5.7 c 



-0.83 a 



34 c 



144 b 



274 c 



44 b 



Vermiculite 



60 



5.2 abc 



-0.92 ab 



32 be 



136 b 



239 be 



38 ab 



VgX slurry 



60 



5.4 be 



-0.89 ab 



24 b 



105 b 



205 abc 



36 ab 



1x slurry 



60 



4.7 a 



-1.01 b 



14a 



57 a 



158 ab 



34 ab 



2x slurry 



60 



4.8 ab 



-0.95 ab 



7a 



43 a 



119 a 



22 a 



Overall mean 



300 



5.2 



-0.92 



22 



97 



199 



35 



'Analysis of variance showed a likely interaction between species and soil type. 

 ^Analysis of variance showed a likely interaction between soil type and root-dip treatment. 



6 



