Analysis and modelling of effects of leaf rust and Septoria tritici blotch on wheat growth

• Published in: Journal of experimental botany Vol. 55; no. 399; pp. 1079 - 1094
• Main Authors: Robert, C, Bancal, M.O, Nicolas, P, Lannou, C, Ney, B
• Format: Journal Article
• Language: English
• Published: Oxford Oxford University Press 01-05-2004; Oxford Publishing Limited (England); Oxford University Press (OUP)
• Subjects: Agronomy. Soil science and plant productions; Biological and medical sciences; Biomass production; Botanics; crop damage; crop loss; Crops, Agricultural - growth & development; Crops, Agricultural - microbiology; Disease models; Economic plant physiology; Epidemiology; Flowers - growth & development; Flowers - microbiology; Fundamental and applied biological sciences. Psychology; Growth and development; Leaf area; leaf photosynthesis; Leaves; Lesions; Life Sciences; Mitosporic Fungi - pathogenicity; Models, Biological; Morphogenesis, differentiation, rhizogenesis, tuberization. Senescence; multiple pathosystem; Mycosphaerella graminicola; Photosynthesis; Photosynthesis - physiology; Plant diseases; Plant Diseases - microbiology; Plant growth; Plant Leaves - growth & development; Plant Leaves - microbiology; Plants; Puccinia triticina; Research Papers: Plants and the Environment; Rust fungi; Triticum - growth & development; Triticum - microbiology; Vegetal Biology; wheat modelling; Puccinia recondita f. tritici; Senescence; Biomass production; Growth; Basidiomycetes; Puccinia triticina; Plant leaf; multiple pathosystem; Biomass; leaf photosynthesis; Leaf area; Spores; Stem; Fungi; Mycosphaerella graminicola; crop damage; crop loss; Ascomycetes; Septoria tritici; Fungi Imperfecti; Photosynthesis; wheat modelling; Thallophyta; ECOPHYSIOLOGIE; PUCCINIA TRITICINA
• ISSN: 0022-0957; 1460-2431; 1460-2431
• DOI: 10.1093/jxb/erh108

A model to predict Septoria tritici blotch (STB) and leaf rust effects on wheat growth was constructed and evaluated in two steps. At the leaf scale, Bastiaans' approach that predicts the relative photosynthesis of a wheat leaf infected with a single disease, was extended to the case of two diseases, one biotrophic and one necrotrophic by considering the leaf rust-STB complex. A glasshouse experiment with flag leaves inoculated either singly with one disease or with two diseases combined was performed to check the leaf damage model. No interaction of the two diseases on photosynthesis loss was observed when they occurred simultaneously on the same leaf. In a second step, the single-leaf model was extended to the canopy scale to model the effects of the leaf rust-STB complex on the growth of a wheat crop. The model predicts the effects of disease on the growth of an affected crop relative to the growth of a healthy crop. The canopy model accounted for different contributions to photosynthetic activity of leaf layers, derived from their position in the canopy and their natural leaf senescence. Treatments differing in nitrogen fertilization, microclimatic conditions, and wheat cultivars were implemented in a field experiment to evaluate the model. The model accurately estimated the effect of disease on crop growth for each cultivar, with differences from experimental values lower than 10%, which suggests that this model is well suited to aid an understanding of disease effects on plant growth. A reduction in green leaf area was the main effect of disease in these field experiments and STB accounted for more than 70% of the reduction in plant growth. Simulations suggested that the production of rust spores may result in a loss of biomass from diseased crops and that stem photosynthesis may need to be considered in modelling diseased crop growth.