Improving germination of Heritage Round Pea Varieties
Many older heritage varieties of peas have a tough seed coat that can lead to delayed or uneven germination. We wanted to investigate whether pre-germination treatments, such as soaking or scarification (abrading the seed coat) would provide a worthwhile improvement in germination.
Just over half of participants (57% for soaking, 61% for scarifying) noticed an improvement in germination, although many of these (26 – 33%) only noticed a very slight improvement.
In reality these effects were quite small when measured, with both soaking and scarification reducing the time to attain 80% germination by c 1 day.
When asked whether they would soak or scarify pea seeds in the future, 32% of participants thought they might try soaking again, and 50% were quite likely or very likely to. Scarifying was less popular, with 53% saying they would definitely not try it again.
The small benefits gained from soaking and scarifying would suggest that, in most cases, they are not worthwhile, and more attention should be paid to creating optimum conditions for germination such as firm even seed bed, correct moisture levels and optimum temperatures (above 10oC for germination).
Many older round varieties of peas have a tough seed coat that can lead to uneven or delayed germination. A pea seed contains an embryo in a dormant state and a starchy food source. It is the rehydration of the starchy food source and the embryo which allows it to germinate. A hard seed coat can greatly slow this process, especially when the seed is in the soil where moisture may be unevenly distributed.
Soaking the seed in water, partially before planting outside can soften this coat, and also initiate the germination process, greatly speeding up emergence. This process is sometimes known as ‘priming’. Damaging or chipping away at the hard seed coat, can also remove barriers to germination. This process is known as ‘scarification’. This can be done by mechanically abrading the seed coat with sandpaper or making a small nick using a knife or nail clippers. The latter is only practical for small numbers of high value seeds. The success of scarification, varies with the type of seed, but is commonly done to improve germination of legumes such as sweet peas. Care must be taken to ensure that abrading the seed does not damage the embryo.
We tested four heritage varieties:
- Espoir de Gembloux – a Belgian variety, producing a heavy crop of ‘melt in the mouth’ peas.
- Frueher Heinrich – a tall German variety producing very reliable crops
- Latvian – a vigorous tall and productive pea, which can be eaten without cooking
- Salmon flowered - compact plants with beautiful, bicolour pink flowers and small, sweet pods
Aims of this experiment
The aims of this experiment are to investigate whether the pre germination treatments of soaking or scarification can significantly improve the germination of older heritage pea varieties.
60 seeds were divided evenly into 3 groups of 20 and labelled as ‘Control’, ‘Soaked’ and ‘Scarified’
They were treated as following:
- Control – no treatment
- Soaked – soak the peas for 12 hours in a plastic container with twice the volume of water to peas.
- Scarified – rub the peas for 1 minute between two pieces of sandpaper until the coat is visibly abraded, revealing the lighter tissue underneath.
After each treatment, the peas were sown at 1 cm depth in separate trays and labelled. All treatments were sown at the same time.
The number of peas germinated was recorded every day.
143 people signed up to do the experiment, of which 75 people sent back results, giving a response rate of 53%
The germination counts from participants were collated. The number of days after sowing (DAS) for the peas to attain 20%, 50% and 80% germination was then calculated
Average days to attain
|% of participants||No improvement||Slight||Large||Vast|
% of participants
|No Never||Maybe||Quite likely|
Both soaking and scarifying seed reduced the time to reach 80% germination by c. 1 day. Although this is a small improvement, 82% of participants thought that they might try or were likely to try soaking seed again. Scarifying seed generated similar improvements but only 47% of participants thought that they might try or were likely to try scarifying seed again. Many of the participants stated that they found scarifying fiddly and time-consuming to do.