Effects of drought and mycorrhiza on wheat and aphid infestation

The impacts of climate change on worldwide crop production become
increasingly severe. Thus, sustainable enhancements of agricultural
production are needed. The present study investigated the effects of
drought and arbuscular mycorrhizal fungi on wheat plants (Triticum
aestivum) and their interaction with aphids. Considering predicted climate
change scenarios, wheat plants were exposed to well-watered conditions,
continuous (CD) or pulsed (PD) drought and plants were grown without (NM)
or with mycorrhizal (AM) fungi. Ear biomass and harvest index were
evaluated when grains were produced. Moreover, drought- and
mycorrhiza-induced changes in the amino acid composition of leaf phloem
exudates were studied and the population growth and survival of Sitobion
avenae aphids on those plants measured. Wheat plants responded differently
towards the irrigation treatments. Under drought stress, ear biomass was
reduced, while AM resulted in an enhanced harvest index. In phloem
exudates especially relative concentrations of the osmoprotectant proline
were modulated by drought. Aphid population size was influenced by the
interaction of drought and mycorrhiza treatment. This study emphasises the
pronounced influence of irrigation frequency on plant performance and
indicates positive contributions of AM that may be relevant for
agriculture.