Effect of sodium 2,2,3,3‐tetrafluoropropionate on the germination, emergence, growth and survival of pasture species

Abstract

SummaryThe effect of sodium 2,2,3,3‐tetrafluoropropionate (tetrapion) on the germination, emergence, growth and survival of pasture species was ascertained in petri‐dishes (21 days) and in soil (114 days). Tetrapion was applied with the water in the petri‐dishes and to the soil surface prior to sowing seeds 2‐mm deep in plastic‐lined glasshouse trays. The rates applied in the petri‐dishes were 0,0.093, 0.187, 0.375, 0.75 and 1.5 kg a.i. ha−1; the same rates, except 0.093 kg a.i. ha−1, were applied in the glasshouse. In the petri‐dishes tetrapion did not affect germination rate nor germination capacity of any species. However, it severely reduced shoot growth (22–78% for the lowest and highest rate, respectively) and moderately reduced root growth per seedling (4–44% for lowest and highest rate). In the glasshouse trays, lower emergence, at 27 days, of five of the sown species on the 1.5 kg a.i. ha−1 treatment compared with the control, was explained by depression of shoot growth. Emergence was not affected at any other rate. Between day 27 and day 114 there was a progressive decline in the number of living seedlings of all species; the magnitude of deaths increased with time and rate of tetrapion. The rating of species for tolerance to tetrapion was: Medicago sativa > Festuca arundinacea > Dactylis glomerata > Phalaris aquatica > Eragrostis curvula. Although Trifolium subterraneum seedlings survived low rates of tetrapion they were still affected at day 114 whereas seedlings of other species were recovering. As tetrapion is readily leached from the soil profile, desirable species must be sown after sufficient rain has fallen to wash it from the soil. In this way it is possible to kill weed seedlings that germinate soon after spraying as well as to establish improved species.