Table 4.-Jnfluence of relative humidity on telio spore germination at 20° C.tO.l 



Relative 

 humidity 

 (percent) 



Saturated salt 

 solution 



Mean number basidiospores 

 cast^ 



20 



KAc 



U 



70 



KCl +NaCl 







90 



ZnS04 







98 



K^Cr^O, 







100 



Water only 



960 



Basis for relative humidity values from Winston and Bates (1960) and Rikerand Riker (1936). 

 Based on 5 telia per treatment at each relative humidity. 



Table 5 .-Effects of freezing on teliospore germination 



Freezing 

 period 





Mean number basidiospores cast^ 







Freezing temperature (degrees C.)^ 





(hours) 



-1 



-4 



-8 



-12 



Not preincubated: 











(control)^ 



812 



589 



594 



622 



6 



778 



294** 



144** 



155** 



24 



511* 



212** 



101** 



81** 



4 



Preincubated: 











6 



789 



422* 



46** 



Q** 



24 



167** 



331** 



73** 



Q** 



^ Based on 9 telia per treatment at each temperature. 

 ^ Temperatures ±0.5° C. 



control group was set aside to correspond to each series of tests at a particular temp- 

 erature. Sizes of telia within all treatment groups at a single temperature were similar. 



whereas sizes varied between temperature series. 

 '^Placed in moist chamber for 6 hours at 18° C. 



*and**Significantly less than control at the 0.05 and the 0.01 levels, respectively, as detected 

 by Duncan's New Multiple Range Test (Duncan 1955). Comparisons were made between 

 treatments within each temperature series. 



uously revolved by a clock-drive mechanism (fig. 9) 

 and germination vi-as analyzed according to the num- 

 bers of basidiospores that fell onto 2 percent water 

 agar (pH 2) in the plates. In the counting process, the 

 casts were divided into intervals corresponding to 3 

 hours of cover revolution. These tests were run in a 

 plant growth chamber with 'cool white' fluorescent 

 lights supplemented by incandescents and in a glass- 

 house on several overcast days. Germination was 

 tested under varying light conditions. Light inside 

 petri plates was about 1,000 foot-candles in the 

 growth chamber and up to 800 foot-candles in 

 the glasshouse (fig. 10). Care was taken during incu- 

 bation to balance temperatures within dark and 



9 



lighted plates. (Temperatures were measured with 

 thermistors inside the plates and the plates were 

 moved to warmer or cooler levels of the growth cham- 

 ber as needed.) Higlier levels of light were not in- 

 cluded, as it proved impossible with this technique to 

 keep temperatures within limits necessary for germi- 

 nation when more light was supplied. 



From the excellent casts of basidiospores 

 indicated in the graph for both light and dark condi- 

 tions, it appears likely that teliospores could germi- 

 nate in the field during nights and during overcast 

 days if temperature and humidity requirements are 

 met. 



