An ecophysiological approach to crop losses, exemplified in the system wheat, leaf rust and glume blotch

Abstract

Effects of leaf rust (Puccinia recondita Rob. ex Desm. f.sp.triticina Eriks.) infection of spring wheat (Triticum aestivum L.) plants ‘Kolibri’ on transpiration rate and leaf-water potential were studied during growth in a climate chamber at various soil-water potentials. The water potentials ranged from −210 J.kg−1 to −1025 J.kg−1. Rust infection has been found to increase the transpiration rate. The magnitude and duration of the increase depended on soil-water potential and the time (growth stage) of inoculation. The transpiration rate of uninfected heads was affected by rust infection of the leaves, also depending on soil-water potential and infection time. Overall resistance of the plants to water flow was determined; sudden changes in resistance due to rust infection concur with high crop losses due to abortion of kernels. Leaf-water potentials were calculated and found to vary in uninfected plants from −1740 J.kg−1 at the lowest soil-water potential to −580 J.kg−1 when water was plentiful. At high soil-water potential, the leaf-water potential of rusted plants was lower than that of uninfected plants, but this was not so at low soil-water potentials. The effects of leaf-water potential on rust growth and water flow through leaves and heads are discussed. Suggestions about the application of the results to breeding for tolerance (= resistance to loss) and, eventually, to prevention of loss by rust in semi-arid areas are given.