GERMINATION OF HELEOCHLOA ALOPECUROIDES (POACEAE) IN VARIOUS CONCENTRATIONS OF HELIUM,NITROGEN, AND CARBON DIOXIDE

The percentages of germination of Heleochloa alopecuroides (Pill and Mitterp) Host seeds were tested in various controlled atmospheres of He, N₂, and CO₂. Atmospheres of 16.7%, 33.3 %, and 88.9 % of each of these gases (thus reducing O₂ concentrations to 17.5 %, 14.0 %, and 2.3% respectively) were introduced into 1000-ml stoppered vacuum flasks, each containing 100 seeds placed on substrates of either sterilized soil or filter paper. The flasks were placed in growth chambers with an 8-hr light period at 20 C and a 16-hr dark period at 5 C. The germination rate was accelerated directly with increased concentrations of He and N₂ but was retarded by increased percentages of CO₂. Control flasks eventually reached nearly the same percentages of germination as those of He and N₂ but at a later point in time.