With peas and beans becoming an ever-increasing element of arable rotations, a recent series of webinars highlighted some important topics for growers.

The Yield Enhancement Network (YEN) in its on-line meetings found that important questions were being raised, such as: Why is the length of time between pea and bean growth stages seemingly associated with yield? Was it bruchid beetle damage or the higher temperatures in June that supressed bean yields this past year?

These were just a couple of the questions raised and though only in their fourth and second years, respectively, the YEN pea and bean projects are already revealing insights that, long-term, could help growers achieve yield potentials.

“Taking into account factors such as light interception, radiation use efficiency, rooting depth and water use efficiency, we’re looking at UK yield potential ranges of 9-16t/ha for beans and 6-10t/ha for peas,” explained Pulse YEN’s project manager, Thomas Wilkinson.

As current yields range from 1-5t/ha for peas and 1-7t/ha for beans, that leaves plenty of scope for improvement. This, it is hoped, will come from YEN’s unique approach which sees the industry working together.

Unlike grain YENs, the pulse projects are are not aimed at competitive yield comparison, but more focused on the sharing of knowledge and experience.

“For now, Pulse YEN’s focus is on improving and stabilising yields and as this year proved, we can learn just as much from lower yielding crops as higher ones,” said specialist seed business PGRO’s Dr Becky Howard.

Last year, both pea and bean acreages grew significantly – by 28% and 38%, respectively. While there’s no doubt wet autumnal weather in 2019 played its part, difficulties with establishing OSR alongside increased demand mean higher pulse acreages could be a longer-term trend.

“Pulses often don’t get the attention they deserve,” observed Iain Ford, BASF's business development manager and YEN sponsor. “With a wide range of potential uses due to their protein content and their contribution to rotations in terms of nutrition and soil structure, they could have an important role to play in improving sustainability within the sector.”

In total, the project analysed 52 bean yields, including 32 yields from this past season. Experts compared the metrics of the top 50% of yield entrants with those of the bottom 50%.

They found statistically significant relationships between yield and potassium in leaf tissues; boron levels in seeds; and bruchid damage to seeds.

Dr Howard theorised that the relationship between bruchid damage and yield is more likely to be associated with environmental conditions with high temperature, leading to increased bruchid levels and potentially causing yield suppression.

“Yield components such as higher seeds/m2, thousand seed weight, total dry matter per shoot, bean dry matter per shoot and harvest index were also associated with higher yields,” explained Mr Wilkinson. “But it’s important to note, it is early days and these relationships aren’t necessarily cause and effect.”

Like grain fields, bean crops with canopies that were greener for longer were also associated with higher yields. This finding was mirrored in further research by PGRO and Hummingbird Technologies, which used Normalised Difference Vegetation Index (NDVI) as an indicator.

Where possible, historical Pea YEN data was added to the 40 pea data sets from the 2019 and 2020 seasons. Taken together, it was higher numbers of plants, not larger plants that tended to produce higher yields.

Statistically, significant relationships were also found through leaf tissue analysis which revealed higher levels of nitrogen, phosphorous, magnesium and zinc were all associated with higher yields.

“These are preliminary associations that are helping us to better understand crop physiology. We don’t yet know which of these factors are most important. We need more crop data and we’re very happy to provide technical support to any growers interested in taking part,” added Dr Howard.