Farzana Nowrin

Candidature:

PhD Candidate

Thesis Title:

Do silicon anti-herbivore defences in rice operate consistently under variable environmental conditions?

Research Project:

Over 300 million years of co-evolution, plants and insect herbivores have developed complex defence strategies, ranging from physical barriers to complex chemical signalling. Silicon (Si), a beneficial element for many cereal crops, has emerged as a key component of these defences by reinforcing plant tissues, priming defence pathways, and enhancing resistance to insect attack. Once taken up, Si is deposited as silica phytoliths in cell walls, deterring herbivores physically, while priming chemical defence pathways and attracting natural enemies via herbivore induced plant volatiles (HIPVs).

However, the effectiveness of Si-mediated defence is influenced by environmental factors, particularly nitrogen (N) availability and rising atmospheric carbon dioxide (CO₂). While N availability regulates Si uptake and allocation within plants, elevated CO₂ can alter plant chemistry and nutritional quality, potentially changing plant–herbivore interactions. Despite their importance, the combined effects of Si, N, and elevated CO₂ on plant defence remain poorly understood.

This PhD project investigates how Si-mediated defence functions under future environmental conditions using rice (Oryza sativa), a silicon-accumulating cereal crop, and the fall armyworm (Spodoptera frugiperda), one of the world's most destructive invasive insect pests. Through a series of glasshouse and laboratory experiments, the research examines how Si, N availability, and elevated CO₂ interact to influence plant nutritional quality, defence chemistry, herbivore feeding efficiency and digestive physiology. The project also explores how these environmental factors modify carbon–silicon defence trade-offs in the plants.

By integrating plant physiology, insect ecology, and global change biology, this research aims to improve our understanding of how Si-based plant defences respond to future climate scenarios and to evaluate the potential of Si as a sustainable strategy for enhancing cereal crop resistance to insect pests while reducing reliance on chemical pesticides.

Supervisory panel:

Professor Scott Johnson, Associate Professor Ben Moore.