Keeping potato crops stress-free has not been easy this year – first it was too wet, then too dry and early crops were threatened by frost.

However, that means it is vital to protect yield and quality potential, and an amino acid-based biostimulant could give crops an essential boost over the coming months, according to Interagro.

Keeping crops in optimum condition is a challenge, especially this year, as the drought, frost damage, wind blow, high UV levels, and even herbicide damage in some crops. “With rainfall at 64% of the national average for March/April, and May the driest on record, drought stress will be a major problem where crops remain unirrigated,” explained Stuart Sutherland, technical manager at Interagro.

“Only certain varieties will be able to cope and any further extremes, wet or heat, will exacerbate the stress impact on the crop. Temperature stress can affect potato crops at any time during the growing cycle.

“Fluctuations in temperature between hot and cold, as we have experienced recently, lead to erratic growth that cause issue with tuber size, numbers and impacts quality, often resulting in growth cracks.

“Sensitive to both minus temperatures and extreme heat, potato plants stop growing above 26°C as they physically cannot draw enough water up to compensate for what they are losing through their leaves. Such extremes later on can stunt the canopy or prematurely senesce it impacting tuber size and yield.”

Crop stress, which reduces the rate of carbon assimilation and decreases partitioning of assimilates to the tubers, is the most detrimental to tuberisation, bulking and tuber yield. Therefore, beating it is a necessity to protect yield and quality potential, explained Mr Sutherland.

“With the potato tuber being mainly composed of photo-assimilates (mostly starch), any mechanism to stimulate photosynthesis and translocation of the end product to the underground stem offers the possibility to increase tuber yield.”

As a solution to this, trials have demonstrated that Bridgeway and Zonda significantly increase yields, by offering some relief through improving root health and increasing the rate of photosynthesis – enabling starch production to continue. “The amino acids in Bridgeway/Zonda – Proline and Serine – help the crop to rebuild catabolised structural proteins, while crucial signalling peptides aid physiological changes in the plant that trigger vital coping and recovery mechanisms.”

What’s more, the biostimulants have proven to stimulate root growth increasing the crop’s access to water and nutrients, crucial during periods of drought, and nutrient stress.

In CMI trials last year, Bridgeway significantly increased yield and margins in potato crops suffering from early drought stress. “Three applications of Bridgeway provided an increased tuber yield of 5.2t/ha (compared to an untreated crop), with an overall tuber yield of 38.08t/ha,” explained Mr Sutherland.

Translated into margin over input cost, these three applications led to an increase of £850/ha, he added.