Tropical Grasslands (1985) Volume 19, 116–120

TECHNICAL NOTE: THE RELATIONSHIP OF SEEDING AND NODULATION TO THE SLOW ESTABLISHMENT OF CLUSTERED CLOVER ON TRAPROCK SOIL

A. DIATLOFF1 and I.F. SWANN2

1Department of Primary Industries, Meiers Road, Indooroopilly Qld 4068
2Department of Primary Industries, P.O. Box 231, Warwick Qld 4370

Abstract

A field experiment over 5 years was carried out to determine whether the build up of seeds or nodule bacteria was responsible for the slow establishment of stands of clustered clover (Trifolium glomeratum), an annual legume grown on traprock soils at Amiens, S.E. Queensland. Nodulation by various strains of Rhizobium used as seed inoculants was followed by the antibiotic marker technique and immune-diffusion serology. Seedling counts were made annually and related to the pattern of rainfall in the area.
The test site initially carried few effective rhizobia so there was a response to the seed applied inoculum. A higher level of nodulated plants resulted from the use of local isolates compared with a commercial white clover inoculum. All strains were recoverable from the trial area after 5 years despite the rigours of the climate and the periodic absence of the host legume.
Despite the favourable initial seedling establishment, plant numbers declined with time. The pattern of autumn and spring rainfall was the most likely cause. Untimely rainfall could cause "false strikes" in late spring and summer with high seedling mortality and failure to flower and set seed. It was concluded that the lack of seed build up in the soil was the main cause of the slow development of stands of clustered clover.

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