Buckley, Annabelle Kate
(2025)
Investigating the physiological effects of fungicides on sugar beet growth and yields.
PhD thesis, University of Nottingham.
Abstract
Sugar beet (Beta vulgaris subsp. vulgaris) is susceptible to a range of foliar diseases, which can damage the plants and result in significant yield losses. Fungicide programs are routinely used in sugar beet cultivation to gain control of the major foliar diseases and protect plant yields. Some fungicides have been observed to improve the physiology and yields of crops, even in conditions where disease is not present, but this relationship has not yet been determined in sugar beet. This project investigated the relationship between fungicides and sugar beet physiology and yields, to determine the physiological reasons that this process may be occurring.
A combination of field, polytunnel and glasshouse experiments was used to investigate the responses of sugar beet plants to a variety of conditions, with a selection of fungicides. The overarching themes were comparing responses to fungicides of contrasting modes of action under droughted conditions, various nitrogen fertiliser levels, and standard field conditions with varieties of differing disease susceptibility. Measurements were taken which included leaf photosynthetic activity, spectral reflectance, canopy cover, and yield data including leaf weight, root weight, and sugar yield. Field experiments were conducted in the presence of disease, but the amount of disease for cercospora leaf spot and leaf rust were relatively low.
Across most of the experiments, the fungicides which tended to show increased yields and more positive physiological responses (and which couldn’t be exclusively attributed to visual biocidal effects of the active ingredient) belonged to the groups of azole + strobilurin combination, and azole + SDHI combination. In the field experiments in particular, the azole + strobilurin fungicide frequently had better trait scores than other treatments, including the no fungicide control, and also resulted in the highest sugar yields. The no fungicide control was frequently the poorest performing treatment, although the reasons for the lack of consistent response across different experiments were unclear.
For the experiments that focused on responses under abiotic stress, namely drought stress and nitrogen limitation, the effects of these stress conditions were highly significant on plant physiology and yields, while the effects of fungicides tended to be more apparent while conditions were otherwise favourable.
There were indications that some fungicides may be effective at reducing the normal stress responses of the plants under abiotic stress, which allowed for more photosynthetic activity to take place even when conditions were not optimal, which subsequently increased yields.
Actions (Archive Staff Only)
 |
Edit View |
Tools
Tools
