EFFECTS UPON GERMINATION 



809 



showed that the germination of 0. odorata and 0. biennis seeds was greatly 

 accelerated by light, but that with dry storage of 7 months or longer the 

 germination of 0. odorata improved in darkness. 



In Oenothera biennis, 0. lamarckiana, 0. suaveolens, 0. muricata, 0. 

 cockerelli, and 0. syrticola (3, 81, 98) the seed coats interfered with water 

 absorption. This interference was partially overcome, and germination 

 was increased considerably by pricking the coats with a pin or subjecting 

 the seeds to a water pressure of 8 atmospheres for 3 days. 



Gassner (26) considered Kinzel's failure to get germination in darkness 

 due to the low temperatures used. He germinated 0. biennis at various 

 constant and daily intermittent temperatures with results given in 

 Table 8. 



Table 8 



The combination of 19° and 28°C. was not so good as the combination 

 of 12° and 28°C. Takiguti found that 0. odorata seeds germinated well 

 in darkness in daily intermittent temperatures, and that immature seeds 

 germinated well in dark at about 10°C. and in diffuse light at about 20°C. 



Ottenwalder obtained 22 per cent germination of 0. biennis seeds in 

 darkness using 0.006 mol. HCl and none without acid. Gassner got 

 increased germination of these seeds with solutions of N compounds 

 combined with intermittent temperatures although the most effective 

 intermittent temperature gave maximum germination without N com- 

 pounds. Takiguti found that KNO3 solutions stimulated the germina- 

 tion of 0. odorata in darkness. 



Lythrum. — According to Kinzel (51, Suppl. I, page 25) Lythrum sali- 

 caria seeds in a germinator at 20°C. for a period of four years gave 100 

 per cent germination in light and none in darkness. L. hyssopifolia seeds 

 gave 17 per cent germination in both Ught and darkness within a few 

 weeks and no further germination except in light. In a later test of 

 Kinzel's (51, Suppl. II, page 118) L. hyssopifolia seed in an illuminated 

 germinator for 2}^ years germinated gradually to 92 per cent. The slow 

 germination in light, and the failure to germinate in darkness were no 

 doubt due to the low temperature used. 



