Physiological responses of wheat ( Triticum aestivum ) to infection with Mycosphaerella graminicola causing Septoria tritici blotch

Glasshouse and field experiments examined the physiological responses of wheat to infection with Mycosphaerella graminicola (anamorph Septoria tritici) with the main aim of elucidating the possible effect of a translocated toxin on plant water relations. It is concluded that infection with M. graminicola reduces water use and growth in well-watered, well-managed crops only if leaf area index is reduced below the value required for full interception of solar radiation. Where this occurs after anthesis, the lower rate of assimilation may be compensated by translocation of assimilates from stem to the grain and possibly by greater green leaf area duration. There was no evidence for effects of a translocated toxin on the measured parameters of plant water relations. The loss in yield in the field experiment is much less than in earlier studies with cvv. Robin and Heron and highlights the need for crop loss assessment in a wider range of years and with modern cultivars which are generally more resistant to M. graminicola than either Robin or Heron.