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Conducted in the field by Dr Rumiana Ray, using the winter wheat variety Gallant, the research assessed fungicide performance on photosystem II (PSII) – a key component in the photosynthetic pathway concerned with capturing sunlight.

Applied at 1 l/ha at growth stages 32 or 39 (T1 or T2), results showed a consistent increase in the efficiency of PSII photochemistry following application of Seguris, reports Dr Ray. "Our results showed that light energy was not wasted but was used productively by Seguris-treated plants," she notes.

Moreover, Dr Ray says Seguris had a significant influence on a second parameter called the performance index of wheat – which she says provides information of the overall physiological status of the plant at the time of assessment.

Five days following T1 application of 1 l/ha of Seguris – which contains 125 g of the SDHI isopyrazam and 90 g of the triazole epoxiconazole – a 12% increase in the performance index was detected, she says. That was compared to plants receiving 93.75 g/ha of epoxiconazole, she adds.

"Towards the end of the growing season, following anthesis, there was a strong positive correlation between PSII efficiency, performance index, crop biomass and yield," explains Dr Ray. "Ultimately, the higher the PSII efficiency and performance index, the higher the yield. Treatment with Seguris achieved 11.9 t/ha. The untreated and epoxiconazole-treated yielded 0.4 t/ha less."

In a second experiment in the glasshouse, plants of Gallant were grown with as little as 15% water availability, to see if a similar effect on PSII efficiency was observed in water-stressed plants.

"The evidence from the field and the glasshouse is that the effect of Seguris on photochemistry is consistent," Dr Ray adds.

David Ranner, technical manager for Syngenta who sponsored the research, says with plans to use SDHI fungicide chemistry on-farm, it will be useful for growers to hear what these results have shown.

"We already know that Seguris offers potent and long-lasting disease control," says Mr Ranner, "and that it delivers improved green leaf retention. If there are also benefits for photosynthesis, it is extremely encouraging to know that these can occur in the absence of appreciable disease."

Note: Photosystem II referes to the water splitting stage in photosynthesis when two molecules of water are split into one molecule of oxygen, releasing four electrons in the process. These electrons are then used in the synthesis of ATP.