EARLY SEEDLING GROWTH OF 3 SPECIES OF DANTHONIA AS AFFECTED BY DEPTH OF SOWING AND NUTRIENT SUPPLY

In an experiment in a controlled environment, seedling emergence of th ree species of Danthonia (D. linkii var. fulva, D. tenuior and D. rich ardsonii) was measured in response to sowing depth. Seedlings of all t hree species did not emerge if seeds were buried deeper than 25 mm. At lesser depths, D. linkii var. fulva showed greatest tolerance to incr easing sowing depth, whilst D. tenuior was intermediate and D. richard sonii was least tolerant of seed burial. In a separate experiment, see dlings of Danthonia linkii var. fulva and two geographically distinct populations of D. richardsonii emerged earlier, grew faster and had a higher biomass than those of D. tenuior in response to nutrient supply . The latter population grew more slowly than the others, but by day 5 4, the number of emergents of D. tenuior had equalled those of the oth er populations. Nutrient addition had little effect on seedling develo pment, except that by day 54, four times normal nutrient level reduced root growth in all four populations. No population by nutrient intera ctions were found for either time to emergence or for seedling biomass up to 54 days from sowing. Increases in shoot biomass and the reversa l of shoot to root ratios occurred between 41 and 54 days after sowing , by which time seedling establishment of Danthonia was complete. Some practical recommendations for field sowings are given based on the re sults of this and other studies.