Assessment of yield loss caused by common root rot in wheat cultivars in Queensland

Abstract

The effects of common root rot (CRR) caused by Bipolaris sorokiniana on grain yield, number of tillers, number of grains and grain weight of wheat plants were determined in four field experiments. Sites with different soil populations of B. sorokiniana were selected and inoculum of the fungus added to some plots. Disease and yield measurements were made on eight cultivars and lines differing in susceptibility to CRR. Timgalen, Songlen and Hartog were susceptible whereas Kite, 1008 C16, 1 4 1 4 and ISWYN 32 were partially resistant to CRR.Grain yield, tiller and grain number, but not grain weight decreased as disease severity increased. Diseased plants had lower tiller numbers than healthy ones and as a consequence a reduced number of grains and grain yield per plant.Five methods were compared for estimating yield loss caused by the disease. Polynomial regression equations for each cultivar between yield and disease rating of sub-crown internodes or multiple regression equations between yield and disease parameters of sub-crown internodes or tiller bases were established. A third method involved the projection of yield losses from one cultivar to other cultivars and in a fourth method yield losses were estimated from actual yields. In addition, an equation Yield loss (%) = 3 46 + 0.23 disease severity) (%) was established in one experiment and used as a fifth method in the other experiments.Yield losses estimated by methods 1 and 2 were similar and higher than those from the other methods. In areas where disease severity is high, methods 1 and 5 appear to be the most suitable for determining yield losses. Losses in a susceptible cultivar, Timgalen, varied between 13.9 and 23.9% whereas those in a partially resistant cultivar, 1008 C16, varied between 6.8 and 13.6%.

Genomic regions associated with common root rot resistance in the barley variety Delta

“…Soil populations of B. sorokiniana were determined as indicated in Wildermuth et al (1992). DArT data were analysed by examining the hybridisation intensity of parental and bulked DNA to individual DArT Markers.…”

“…This disease is a significant constraint in the dryer temperate cereal growing regions of the world, and has been particularly damaging in Syria, Canada, USA and Australia (Wildermuth 1986;Conner et al 1996;Van Leur et al 1997;Kumar et al 2002;Tobias et al 2009). In Australia, CRR has been reported in wheat and barley cropping fields in every mainland state, with estimated yield losses of up to 24% reported in Queensland (Wildermuth et al 1992).…”

“…Common root rot infected seedlings develop dark brown necrotic lesions on the roots, crown and lower leaf sheaths (Kumar et al 2002). The disease impairs the functioning of roots and crown, resulting in fewer tillers and heads, which causes a reduction in grain yield and quality (Wildermuth et al 1992). As high soil temperatures and low soil moisture appear to contribute to the severity of the disease, damage due to CRR can vary widely from year to year in a given location (Van Leur et al 1997;Kumar et al 2002;Mathre et al 2003).…”

“…This disease is a significant constraint in the dryer temperate cereal growing regions of the world, and has been particularly damaging in Syria, Canada, USA and Australia (Wildermuth 1986;Conner et al 1996;Van Leur et al 1997;Kumar et al 2002;Tobias et al 2009). In Australia, CRR has been reported in wheat and barley cropping fields in every mainland state, with estimated yield losses of up to 24% reported in Queensland (Wildermuth et al 1992).Integrated strategies for controlling B. sorokiniana on barley include soil and residue management, chemical control, crop rotation and resistance breeding (Mehta 1988; Steffenson 1997). Wildermuth and McNamara (1991) demonstrated that rotational strategies involving a range of other crops, in particular lucerne, resulted in the reduction of soil populations of B. sorokiniana and thus a reduction in the severity of CRR.…”

Sustaining productivity of a Vertosol at Warra, Queensland, with fertilisers, no-tillage or legumes. 9. Production and nitrogen benefits from mixed grass and legume pastures in rotation with wheat

“…Briefly, the incidence and severity of common root rot and crown rot of wheat were assessed from randomly collected 50 wheat plants with their roots from each plot at anthesis. The subcrown internode of each plant was examined for the extent of lesions due to common root rot (Wildermuth et al 1992). Incidence of crown rot was assessed by examining the first internode of tillers for honey brown to dark brown discoloration.…”