Stuart Sutherland, technical manager at Interagro talks about using biostimulants.

After a challenging season to date, incorporating biostimulants into crop management programmes for the remainder of the season could help to safeguard remaining yield and protect profitability.

This spring repair, recharge and building resilience are the key objectives for growers seeking to recover plant health in winter crops to prevent a further slide in yield potential. In spring crops – if the past few years are anything to go by – optimising establishment, getting crops off to the best start, and preparing them to cope with dry conditions as the season develops will also be crucial.

There’s no denying how tough this season has been up and down the country, and with the heavy rain continuing into spring, protecting what’s left of winter hectarage and getting spring crops off a strong start is vital.

For Scottish growers, spring barley is obviously a key crop, so here many will be looking to optimise rooting to boost nutrient uptake, support tillering – key for yield – and also mitigate stress where possible to avoid the onset of stress-triggered diseases like ramularia, which could further damage yield potential.

This is where biostimulants have a place, as the right product can help with all of those things, continues Stuart. “Something like Interagro’s Bridgeway promotes healthier crops by stimulating growth, optimising resource use efficiency and crucially, it increases recovery and immunity against stressful growing conditions, something that’s becoming increasingly vital to growers.”

Strong roots, strong start

A good root system is at the heart of any productive barley crop and this season in particular, applying a proven biostimulant known to boost rooting is advisable to help put down a strong support system and support nutrient uptake.

Taking Bridgeway as an example, it contains high levels of root stimulating amino acids and peptides that increase the lateral roots and root length density of plants.

The more robust and expansive root systems enable crops to capture nutrients readily available in the soil and leached water and nutrients lower down.

Building strong root systems with Bridgeway early in the life of the crop ensures the supply of water for photosynthesis and transpiration that is needed for highly efficient crop production.

The stimulation of growth regulating phytohormones also promotes shoot growth and biomass production, supported by more abundant resources to optimise plant growth and development.

Keeping stress out

As well as helping plants access nutrition and water vital for growth, a good root system also reduces the risk of deficiency stress – something which makes crops much more sensitive and vulnerable to pathogen attacks. If we look at the crops in the ground now, and the conditions spring crops are going into, there are going to be a lot of stressed crops this year.

In spring barley, the big concern with that is the increased risk of ramularia, which is triggered by stressful growing conditions early season. Environmental stresses such as waterlogging, high light intensity and drought can all exacerbate the disease.

When it comes to mitigating stress in crops, there are some general guidelines to get the best from biostimulants.

The first step is to identify the specific stress factors that are likely to affect crops, both now and as the season develops — such as cold soils, nutrient depleted soils, potential drought periods, heat stress. These are all stresses for you and your crops that biostimulants can help to mitigate against.

Ask yourself how much importance are you placing on the plant’s own defence system?

Consider your fertiliser and crop protection strategies – if you are aiming to reduce reliance on them this season then you’ll need to put greater emphasis on building plant health with nutrition and biostimulants early in the growing cycle to produce more resilient crops.

The timing of biostimulant application is also crucial to achieve best results. It’s vital you consider timing in relation to the stress factors and when your biostimulant application is most likely to mitigate against the potential threats. With regards to minimising ramularia threats applying before flowering, to prevent these stress factors, can all help reduce the triggers for the disease.

While biostimulants are by no means a silver bullet, with extra pressure on spring crops to do well this year, the benefits of something like Bridgeway could offer growers a very welcome return on investment. “We know that the mood is already rather sombre in terms of what harvest 2024 will bring, and though growers can’t do much about the weather so far, or what’s to come, they can prepare crops to better withstand stress situations and continue to grow to protect as much yield potential as possible.

Protecting potato potential

With much of Scottland’s cropping area down to potatoes, there is immense pressure on keeping crops stress-free – though this is not an easy task.

Potato potential including the number of progeny tubers and the rate of tuber bulking is established early in the season at about the time tubers reach 10mm in size. Stressful growing conditions during this time can therefore have a big influence on crop yield.

Once tuber bulking has started, the rate cannot be increased, but can be reduced or interrupted by stress. The earlier in the season heat stress occurs, the more negative its impact on the growth and yield. Every 5ºC increase above the optimum temperature of 20ºC can decrease the rate of photosynthesis by 25%.

Potatoes start to suffer from high temperature stress as temperatures exceed 25ºC, when the rate of photosynthesis begins to decline, significantly reducing the partitioning of sucrose translocation to tubers.

Heat stress can therefore reduce the rate of bulking, at 30ºC it can pause it altogether as the rate of energy used by respiration to keep cool, exceeds the rate at which energy is produced by photosynthesis.

Biostimulants can help in this situation too, by priming potato crops to better withstand the effects of heat stress. “Bridgeway has been proven to do just this in many trials over numerous years, most recently increasing bulking by up to +2.8 t/ha per week compared with untreated crops.

In terms of timing, applying at the onset of bulking has the greatest potential to mitigate the effects of stress on the crop’s bulking and yield potential – and could just make all the difference this season.