Does dormancy protect seeds against attack by the pathogenic fungus Fusarium tricinctum in a semiarid grassland of Northwest China?
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Soil fungal pathogens can result in the failure of seedling establishment, but the effects of fungicide applications on seed/seedling survival have differed among studies. We assumed that the variation may relate to seed dormancy/germination characteristics and hypothesized that nondormant germinating seeds are more likely to be killed by fungal pathogens than dormant seeds.
Dormant and nondormant seeds of Stipa bungeana and Lespedeza davurica were inoculated with a pathogenic fungus Fusarium tricinctum under laboratory and field conditions. The outcomes of seed/seedling fate and other parameters were evaluated.
In the laboratory, nondormant seeds inoculated with F. tricinctum developed white tufts of mycelium on the radicles of germinating seeds causing them to quickly die, but dormant seeds remained intact. In contrast, in the field inoculation with F. tricinctum did not cause higher mortality of nondormant than dormant seeds but resulted in higher percentages of seedling death before they emerged from soil than the controls.
Our results suggest that dormancy protects seeds from being attacked by some pathogens by preventing germination, but the protection is lost once germination has commenced. Further study involving various plant species with more seeds is needed to assess the generality of this pathogen-seed interaction hypothesis.
KeywordsDormancy Fungal pathogens Grasslands Pathogen-seed interactions Seed burial
We wish to thank Craig McGill of Massey University, New Zealand for reading this manuscript. We thank Xiaowen Hu of Lanzhou University for help in the revision of this manuscript, and Chao Xia for help in the making of figures. We also acknowledge the excellent informed comments from the two referees. This research was financially supported by National Basic Research Program of China (2014CB138702), National Public Welfare Industry of Agricultural Science and Technology Special Projects (201303057) and the National Nature Science Foundation of China (31402132).
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