Physiological characteristics of high yielding Pea YEN crops

At the end of 2023, the Pea YEN reached a milestone of over 100 yields. Funded by the NCS project an association analysis was undertaken on the Pea YEN data set This has allowed us to take a deeper dive into the characteristics associated with the higher yielding pea crops in the network, specifically being more precise about the analysis of different variety types (marrowfat peas vs non-marrowfat peas) and which physiological factors effect pea yields. More information and a discussion about the results more broadly than physiology can be found here: https://farmpep.net/resource/what-have-we-learnt-pea-yen-so-far.

This information is also summarized in the now available BASF Pea Growth Guide.

For peas, the period between the start of flowering and start of seed filling is defined as the critical period determining final yield. The principal components of yield are seeds/m2 (the number of seeds per unit area in the crop at harvest) and seed size (often measured as TSW). Seeds/m2 results from a combination of plants/m2, shoots per plant, pods per shoot and seeds per pod, which are affected and determined by different factors. Plant population (or plants/m2) is determined by seed rate and establishment, whilst shoots per plant is determined during stem extension and influenced most by plant spacing and water supply. Pods per shoot relates to the number of nodes per shoot and may be affected by plant height and conditions during stem extension. Flowers may be aborted this year due to high temperatures and drought. Similarly, the seeds per pod is sensitive to the amount of photosynthesis during the critical period and seed embryos can be aborted under stressful conditions.  

Whilst these yield components can be measured in any crop, it should be noted that extra value arises from benchmarking your own crop within the YEN, so you can see whether these factors in your crop are on the low or high side given the unique conditions of that particular year. Benchmarking nutrition and agronomy choices can give immediate comparisons to other crops, and as development of each yield component (e.g plant population, shoots per plant, pods per shoot, seeds per pod, seeds per m2 at harvest and seed size) occurs during different phases of growth (see Figure 1), this means the analysis of these characteristics can indicate when a crop may have been positively or adversely affected by management or conditions.

Figure 1: Yield component development of peas through time. Courtesy of the BASF Pea Growth Guide.

A summary of the key yield component results from the Pea YEN are below.

Pea YEN Crop Development and Yield Components*

• Highest yields associated with early plant establishment and earlier flowering. However, it is important to ensure crops are established in good conditions.
• Across all variety types, highest yields positively associated with:
  • Seeds/m2 and pods per shoot
  • Plant height, individual shoot biomass, crop biomass and Harvest Index (ratio of seed to total biomass)

• In addition, splitting crops out into variety types reveals that:
  • TSW (seed filling) is important within variety types
  • In non-marrowfats highest plant populations are associated with increased yields. Note that most marrowfat entries in the YEN were above economic optimum plant populations
• High yields come from large well podded plants
  • Maximise light capture and avoid stress through flowering to increase sink size
• Seed filling is important for seed size
  • Avoid stress during seed fill and maximise canopy duration

*It should be noted that the analysis used is an association analysis and cannot disentangle cause and effect (it cannot say what is driving yield) but combined with expert judgement we should be able to develop practical messages. ‘Effect sizes’ help explain the average variation of an average yield, but it should be remembered that many factors will be influencing yield. A straight line is fitted to give the REML effect size above the average, but in reality, effects may level off eventually.
 

Whilst associations with higher yields were seen in early sown crops in the YEN, the importance of ensuring the crop goes into the best seedbed and soil conditions as possible should not be overlooked.

We are happy to announce that Pulse YEN sponsors may be willing to cover the costs of your Pea YEN or Bean YEN entry. To enquire about sponsorship, follow three easy steps:

1. Log into your YEN account here
2. Click ‘Enters YENs’ and after choosing your YEN of interest, select ‘I am a grower who would like to apply for a sponsored place’
3. After completing your entry form, ADAS will pass on your enquiry to the sponsors and ask for a response within two weeks
4. If the sponsor agrees then they'll get in touch directly to get you registered, or ADAS will pass on the details to fully register your entry

Alternatively, prospective YEN members are welcome to discuss sponsorship directly with any contacts they already have, or can cover their own costs as an individual entry. Once you are registered you will have full access to the Pulse YEN 2025 and the inclusive sample analysis (Peas; soil nutrition, foot rot risk, leaf nutrition, seed nutrition, pea quality, grab sample for crop physiology. Beans: soil nutrition, leaf nutrition, seed nutrition, bruchid beetle damage, grab sample for crop physiology) although please note that some sample kits are subject to time restrictions or may be on a first come, first served basis for a limited number of entrants.