Establishing tagasaste from seed in Waikato hill country

Abstract

Tagasaste (tree lucerne) can be difficult to establish from seed due to its hard seed coat and high levels of seedling mortality. Three experiments were performed. Experiment 1: Effect of gibberellic acid, potassium nitrate, seed nicking + soaking in warm water (38oC for 24 hours), soaking seeds in boiling water and a coldwater control on germination. The highest germination percentage occurred from the warm and boiling water treatments. Experiment 2: Effect of slug bait, rhizobia and phosphorus fertiliser on establishment of tagasaste seed which had been hand sown into a herbicide-treated pasture. Of the 1600 hand-sown seeds, emergence was negligible, and no treatments varied significantly from the untreated control. Greater pasture suppression is required for successful establishment. Experiment 3: Examined removal of 20%, 40%, 60% or 80% of the height of a seedling on tagasaste branching. Branch number was similar for all treatments 83 days aftertrimming the main stem. Removing 20% or 40% of the seedling height produced three-fold greater edible dry matter than when 80% of the seedling height was removed (P<0.001). Although pruning treatments did not affect branch number, a less severe pruning regime resulted in the regrowth of the greatest amount of edible dry matter.