Establishment of small-seeded perennial grasses on black clay soils in north-western New South Wales.

Abstract

A range of native and exotic perennial grasses was examined for relationships between seed and seedling features and establishment success on cracking black clay soils of the north-westem slopes of New South Wales.

The features examined included the effect of temperature on the speed of germination and cumulative total germination, the effect of the duration of water availability in the seedbed on seedling emergence and the rates of seedling extension. Seedbed temperatures were also monitored during the spring at the Inverell Research Centre.

No single seed or seedling feature was consistently associated with establishment success. The two species with the highest rating for establishment, Dichanthium sericeum (R.Br.) A. Camus and Bothriochloa macra (Steud.) S. T. Blake, gave good seedling emergence with only 3 days of seedbed watering, had early and rapid seed germination, germinated well over a wide range of temperatures and had fast root and shoot extension rates. Chloris gayana Kunth, with the lowest establishment rating, had low ratings for all characteristics examined except that it had a moderate speed of germination. Advantageous features at one stage of the sequence from seed to established plant can compensate for weaknesses at another stage, e.g, the fast root and shoot growth rate of Panicum decompositum R. Br. compensates for slow speed of germination, to give a good establishment rating overall.