Breeding progress of disease resistance and impact of disease severity under natural infections in winter wheat variety trials

F. Laidig,S. Hadasch,D. Rentel,T. Miedaner,T. Feike,B. Klocke,H. P. Piepho

doi:10.1007/s00122-020-03728-4

F. Laidig, S. Hadasch + Show 5 more

Open Access

https://doi.org/10.1007/s00122-020-03728-4

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Abstract

Key messageBreeding progress of resistance to fungal wheat diseases and impact of disease severity on yield reduction in long-term variety trials under natural infection were estimated by mixed linear regression models.This study aimed at quantifying breeding progress achieved in resistance breeding towards varieties with higher yield and lower susceptibility for 6 major diseases, as well as estimating decreasing yields and increasing disease susceptibility of varieties due to ageing effects during the period 1983–2019. A further aim was the prediction of disease-related yield reductions during 2005–2019 by mixed linear regression models using disease severity scores as covariates. For yield and all diseases, overall progress of the fully treated intensity (I2) was considerably higher than for the intensity without fungicides and growth regulators (I1). The disease severity level was considerably reduced during the study period for mildew (MLD), tan spot (DTR) and Septoria nodorum blotch (ear) (SNB) and to a lesser extent for brown (leaf) rust (BNR) and Septoria tritici blotch (STB), however, not for yellow/stripe rust (YLR). Ageing effects increased susceptibility of varieties strongly for BNR and MLD, but were comparatively weak for SNB and DTR. Considerable yield reductions under high disease severity were predicted for STB (−6.6%), BNR (−6.5%) and yellow rust (YLR, −5.8%), but lower reductions for the other diseases. The reduction for resistant vs. highly susceptible varieties under high severity conditions was about halved for BNR and YLR, providing evidence of resistance breeding progress. The empirical evidence on the functional relations between disease severity, variety susceptibility and yield reductions based on a large-scale multiple-disease field trial data set in German winter wheat is an important contribution to the ongoing discussion on fungicide use and its environmental impact.

Highlights

Wheat is one of the world’s most important staple foods and is susceptible to several important plant diseases (Savary et al 2019)
The analysis aims, first, to quantify the long-term change of yield and disease severity of 6 major fungal diseases of winter wheat, second, to evaluate the effect of variety age on yield potential and disease susceptibility of varieties and, third, to predict yield reduction under natural multiple disease severity conditions relative to fungicide- and growth regulator-controlled yields
For all 5 diseases we found a significant interaction of trial disease severity (TSv) with the variety disease susceptibility (VSc) levels, demonstrated by diverging lines in Fig. 7, especially for brown (leaf) rust (BNR) and yellow/stripe rust (YLR)

Summary

Introduction

Wheat is one of the world’s most important staple foods and is susceptible to several important plant diseases (Savary et al 2019). The on-farm yield in Germany rose considerably from about 55 dt ha−1 in 1983 to more than 76 dt h a−1 to date (mean 2015–2019) (Stat J 2019). This increase was achieved by higher-input cropping systems based on improved crop management, improved fertilizer application, more effective crop protection measures and new improved varieties with higher yield potential and higher resistance to diseases. Yield losses due to fungal diseases are hampering progress for higher on-farm yields in winter wheat. Numerous studies on yield loss in winter wheat due to fungal diseases have been published

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