Flavonoid rich complex biostimulants and their role in increasing global crop yield

Abstract

There is an urgent need to increase the global food supply for a rapidly growing population. Simultaneously there is a desire to reduce the use of agrochemicals, including fertilisers, to protect the environment and a requirement to mitigate against increasing abiotic stresses due to climate change.

The aim of this study is to determine if flavonoid rich complex biostimulants can be used as a potential enhancement to current best agronomic practice to increase yield in important food crops in different climates and get a better understanding of their mechanisms of action by investigating their effect on differential gene expression in Arabidopsis thaliana.

Extracts from exotic plant sources rich in polyphenols and bioflavonoids were assessed, the extracted flavonoids characterised using mass spectrometry and combined with other biostimulatory compounds to create complex biostimulants. These formulations were applied to rye grass, lettuce and mustard in greenhouse experiments in unstressed and stressed conditions to establish their efficacy in drought conditions and with reduced nitrogen availability. The most efficacious formulations were used in commercial field trials in different climates to measure crop yield increases on; grapes, potatoes, peppers, tomatoes, lettuce, spinach, onions, coriander, kale, winter wheat and spring barley.

RNA sequencing was used to identify differentially expressed genes in Arabidopsis thaliana exposed to the flavonoid rich plant extracts. These genes were assessed for their roles in important metabolic pathways. These complex formulations increased plant tolerance to reduced nitrogen and drought stress. They affected crop yield ranging from 66% increase in coriander, 44% in grapes, 35% in spinach, 5.2% in potatoes and showed no effect on cereals. The plant extracts influenced many key metabolic pathways, including flavonoid biosynthesis, starch and sucrose metabolism and abiotic stress management.

These complex biostimulants were shown to increase crop yield in multiple commercial field trials in different climates and were shown to up-regulate key metabolic processes in Arabidopsis.

Thesis is embargoed until 31 July 2030.

Date of Award	Jul 2025
Original language	English
Awarding Institution	Queen's University Belfast
Sponsors	Maxstim Ltd
Supervisor	Colin Fleming (Supervisor) & Fuquan Liu (Supervisor)