ABSTRACT
A pot experiment investigated the effects of root diseases (Pythium and Rhizoctonia) under drought conditions at either tillering or anthesis stages on the water-use efficiency (WUE), water relations, and yield components of wheat cultivars Janz and Mulgara. The pathogens reduced transpiration in Janz during drought at tillering and in both cultivars during the period of recovery after drought at anthesis. However, the pathogens did not affect WUE. WUE did not differ between well-watered plants and those droughted at tillering but it was reduced by 80% by drought at anthesis. Un-infected plants of cultivar Janz subjected to drought at tillering had a higher total water potential (Ψw) and osmotic potential (Ψs) than diseased plants. However, Ψs of un-inoculated plants that were droughted at anthesis was lower than diseased plants in the period following anthesis. Yield components were significantly higher in well-watered than droughted plants and higher in cv. Mulgara than cv. Janz. The pathogens affected transpiration during tillering, but not at later stages, when roots developed beyond the inoculation point. Although the pathogens caused damage to the roots, the effects on water relations parameters were minor. This suggests that wheat can tolerate moderate levels of these root diseases under drought.
Acknowledgments
The authors would like to thank the Australian Winter Cereals Collection (AWCC), Tamworth for their assistance in providing cvs. Mulgara and Janz seeds. We thank Dr Stephen Barnett for supply of the isolate of Rhizoctonia. We also thank Mr Michael Faint and Mr Richard Willis for technical assistance
Disclosure statement
No potential conflict of interest was reported by the authors.