Germination and Dormancy of Themeda australis, Danthonia Spp., Stipa bigeniculata and Bothriochloa macra

Abstract

The germination and dormancy of Themeda australis, Danthonia spp., Stipa bigeniculata and Bothriochloa macra were investigated in whole dispersal units or caryopses. Germination of non-dormant units of the four species was not affected by light but was delayed by low temperatures. Such temperature regimes depressed the germination capacity of Themeda while alternating temperatures with a range greater than 10°C depressed the germination of Bothriochloa. The level of germination of Danthonia and Stipa was not affected by any of the temperature regimes used. Dormancy was reduced either by the application of gibberellic acid at concentrations of 100 ppm to 1000 ppm or by stratification. In addition, application of kinetin ( 10 -4M ) or opening the lemma suture broke the dormancy of Stipa dispersal units. The breakdown of dormancy during dry storage was also examined. Temperature alternations with maximum temperatures greater than 40°C reduced the level of dormancy of Themeda and Stipa within 1-2 months.