Table I . --Effect of volatile compounds from five ponderosa pine plant materials 

 on the germination and radicle growth of ponderosa pine seedlings. 



Treatment 



: Germination 





Growth rate^ 





: Experiment : Experiment : 

 : A : B : 



Experiment : Experiment 

 A : B 





Percent 





cm/ day 





Control 



Mo.Oa 



57.3a 



0.74a 



0.86a 



Root 



40.0a 



70.0a 



.77a 



.85a 



Litter 



33.3a 



52.0a 



.84a 



.93a 



Green needle 



32.0a 



65.3a 



.80a 



.85a 



Duff 



29.3a 



40.0a 



.95a 



.90a 



Bark 



28.0a 



61.3a 



.79a 



.84a 



^All numbers followed by different letters are significantly different at the 5 percent 

 level or greater. 



^Growth rate was obtained by dividing average seedling length per replication by average 

 seedling age per replication. 



larger seedlings. Since seedling age certainly influences seedling size, growth rates 

 were computed to eliminate the effect of age differences and allow concentration on 

 treatment differences. 



The entire experiment was repeated using fresh plant material collected on the 

 same date but stored in plastic bags in a cold room. The two experiments were iden- 

 tical except for the length of the germination periods. In the first experiment A, 

 the germination period was 14 days and in the second experiment B, only 10 days. The 

 germination period was longer in experiment A because of slow germination rates. 



For statistical analysis, one-way analysis of variance tests were used. Following 

 these, the Newman-Keuls test for multiple comparisons was utilized to compare treatment 

 means (Hamilton 1965). The homogeneity of the variances was analyzed in all experi- 

 ments prior to the analysis of variance. 



Results 



The results of experiments A and B are provided in table 1. It is apparent that 

 there were no volatile compounds in the green needles, roots, bark, surface litter, 

 and decomposing duff of ponderosa pine that inhibited the germination or radicle growth 

 of pine seedlings. 



Tests for Water Soluble Toxins 



Materials and Methods 



One month prior to the start of this experiment, buckets lined with plastic bags 

 and covered with a double layer of cheesecloth secured by rubber bands were placed in 

 openings and beneath the crowns of large ponderosa pine trees at the game range. The 

 "pure" rain water was collected in the openings while that collected beneath the crown 

 canopy was considered at natural crown leachate or throughfall and a potential source 

 of phytotoxins. In addition, the rain water that ran down the bark (stemflow) was 



5 



