Crop Tolerance of Foliar Pathogens: Possible Mechanisms and Potential for Exploitation

Crops that feed the world 4. Barley: a resilient crop? Strengths and weaknesses in the context of food security

“…However, in high radiation environments the benefits may only be observed in large canopies (Reynolds et al 2000). In smaller canopies, benefits from the altered distribution of light within the canopy associated with an erect leaf habit may be offset by a reduction in the total amount of radiation intercepted (Bingham and Newton 2009). …”

“…The relationship between canopy size (GAI; green area index; green area per unit ground area) and radiation interception is non-linear and a barley canopy with a GAI of 5 intercepts around 95% of incident radiation depending on the canopy architecture and its light extinction coefficient (Bingham and Topp 2009). Canopies with prostrate leaves tend to intercept more radiation with a given canopy area than those with erect leaves, but the effect is greatest when the canopy area is small (Angus et al 1972;Bingham and Newton 2009). Although barley varieties can differ widely in their height, leaf and tiller growth habit, the effect on radiation interception is often limited in canopies of adequate GAI.…”

Identifying traits leading to tolerance of wheat to Septoria tritici blotch

“…However, mechanistic models need a detailed characterization at the crop level which is often incompatible with the screening capabilities among the hundreds of genotypes regarded by breeders. After an extensive review together with a sensitivity analysis using an existing crop model, Bingham and Newton (2009) suggested to focus on photosynthetic properties of the canopy, specifically on crops able to adapt their radiation use efficiency in response to disease (Zuckerman et al, 1997). Yet simple traits using more conventional source-sink characteristics were still needed to screen tolerant genotypes at a large scale.…”

Control of foliar diseases in barley: towards an integrated approach

“…The potential for nonspecific effects of fungicides and asymptomatic pathogen infection complicates the measurement of tolerance. It may be necessary to develop methods of assessing disease that do not rely on measurements of visible symptoms, such as quantitative PCR or serological techniques, and on methods for varying disease severity that do not involve fungicides (Bingham and Newton 2009). …”