Abstract
New crops with greater capacity for delivering ecosystem services are needed to increase agricultural sustainability. However, even in these crops, seed yield is usually the main criteria for grain domestication. This focus on yield can cause unintended structural and functional changes. Leaves of selected plants tend to be more vulnerable to infection, which can reduce performance, assimilates, and ultimately yield. Our objectives were to determine the impact of rust (caused by Puccinia silphii) on yield and leaf function in selected Silphium integrifolium (Asteraceae) plants. We tested the effect of a fungicide treatment on rust severity and yield, compared the rust infection of individuals in a population selected for yield, and related this to chemical changes at the leaf level. We also estimated heritability for rust resistance. We found that productivity indicators (head number and weight, leaf weight) and leaf processes (photosynthetic capacity, water use efficiency) were reduced when silphium leaves and stems were more heavily infected by P. silphii. Leaf resin content increased when susceptible plants were infected. Fungicide treatments were effective at reducing rust infection severity, but were ineffective at preventing yield losses. We propose that disease resistance should be included early in the selection process of new perennial crops.
Highlights
Diseases and herbivory are key factors in determining yield in crops, the process of the domestication of wild plants has been generally analyzed in terms of yield and yield components and less in terms of specific disease resistance or the potential factors contributing to the resistance
Structural and functional changes resulting from the selection for yield, such a leaf thickness, cell size, and secondary metabolites are traits known to influence the response to pathogens [2,3,4]
We found a range of rust infection severity in silphium plots growing in Central Kansas, from 0–20% infection
Summary
Diseases and herbivory are key factors in determining yield in crops, the process of the domestication of wild plants has been generally analyzed in terms of yield and yield components and less in terms of specific disease resistance or the potential factors contributing to the resistance. During early stages of domestication in seed crops, disease resistance tends to be captured only as it affects seed yield and potentially persistence in perennial crops. Unintended structural and functional changes can occur together with yield increase, and there is recent evidence of anatomical and functional changes at the leaf level that occur very early in the domestication process [1]. Among a group of new perennial grain crops under domestication, Silphium integrifolium Michx. (silflower, silphium, rosinweed) has been selected as a new dual use oilseed and biomass crop [5]. Silphium is native to central and eastern North America and was selected for domestication primarily due to its drought tolerance and high seed oil content
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