AGUSTlN C. BECERRA STIEFEL¹, R.A. DATE² and N.J. BRANDON²

¹Department of Plant Production , University of Queensland, St Lucia, Queensland, Australia
Present address: W. Paunera 153, 5000 Cordoba, Argentina
²CSIRO Tropical Agriculture, St Lucia, Queensland, Australia

Abstract

The survival of Rhizobium strain CB3126 on inoculated seed of Desmanthus virgatus cv. Bayamo was determined after 3, 7, 14, 28 and 39 days storage at 25, 35, 45 and 55°C. Survival was assessed by observing the presence or absence of nodules on aseptically growing desmanthus inoculated with material washed from the stored seed. Plant colour, height and dry weight were compared with those of plants grown from seed freshly inoculated with CB3126 and plants grown with fertiliser N.
Temperatures above 45°C significantly reduced bacterial survival after only 3–7 d of storage. At 35°C, nodulation was reduced significantly when the inoculated seed was stored for 14 d or longer. There was no effect of storage time on final nodulation when seed was stored at 25°C. However, early chlorosis of plants indicated that nodulation was delayed by the longer storage times, even at 25 and 35°C. The dry weight of desmanthus inoculated with freshly prepared peat was significantly higher than that following storage in all but the 25°C-3 d storage treatment.
The implications of these observations for field sowings of inoculated seed of Desmanthus virgatus are discussed in relation to seedling nodulation and establishment.