Epsilon Archive for Student Projects

Abstract

Cultivar mixtures presents a possible method of diversifying the agricultural landscape and provide ecosystem services. Interactions between different plants emissions of volatile organic compounds (VOC) are known to be able to induce resistance to aphids, and research suggests that mixtures of different cultivars will have different responses to VOC that lead to different aphid settling tendencies. The underlying hypothesis in this study is that differences in constitutive emissions are different in different cultivars drives the induction of reduced aphid settling in different cultivar mixtures. This experiment analysed the chemical composition of several wheat and barley cultivars constitutive emissions using TD-GC-MS. Aphid settling tests of cultivars exposed to VOCs from other cultivars were conducted and compiled with previous research to identify which cultivar emitters induce aphid resistance. Multivariate statistical tool Random Forest was employed to find patterns in similarities and dissimilarities between cultivars, as well as identifying which compounds are responsible for the distinction. The constitutive emissions of cultivars bred for different climates, and even those bred for the same climate were distinct in volatile profile composition. Within a dataset of Swedish barley cultivars, there is a clear separation of inducers and non-inducers in their volatile profile composition. The differences between emitter and receiver pairs that separates inducer and non-inducers are best explained by individual parings, rather than general patterns shared within species.