Baby leaf has increased in value as a salad crop over recent years, with £260m of bagged salad sold in 2005 to a staggering £1.1bn in 2017. NIAB hosted an Agri-Tech Week event at its Park Farm Innovation Farm to discuss what would be needed to grow the crop 24/7 with minimal waste to maximise the potential of this crop.
NIAB is one of the partners in the Hy4Dense programme which is looking to design a soil-less hydroponics system optimised for baby leaf – rocket, spinach and lambs lettuce.
Graham Taylor, Research Scientist at NIAB, explained how the programme, which includes partners in the Netherlands and Belgium, will be experimenting with different types of growing mediums and nutrition and designing a hydroponic system complete with LED lighting.
There are several different types of hydroponic system:
- Aeroponics – misting around the roots
- Ebb and flow – where a reservoir is used to top up and refresh the medium
- Droplet hydration to the root zone
The benefits of hydroponics include:
- Higher density planting
- Table-top product so easier to automate the harvesting
- Reducing water usage – hydroponics uses 20x less than soil
- Better pest and weed control and reduced use of plant protection products
- Opportunity to grow closer to consumer and closer matching of supply to demand
Crops like lettuce, strawberries and tomatoes adapt well to hydroponics, but baby leaf has particular challenges. These challenges were discussed by the speakers.
Breeding for hydroponics – Justin Roberts, Vegetable Breeder, Elsoms Seeds
Improving vigour – Lettuce experiences transplant shock when the seedlings are transferred because of the very fine roots, which impacts establishment of the plants. To overcome this Elsoms has been trying to investigate the genetic markers that determine root development, using a cross between an iceberg and rocket. The plants are grown in a 2D hydroponic system – like growing plants on a piece of paper – so the fine root hairs are apparent.
The study found genetic diversity that influenced primary root length, lateral roots, fine hair structure and also the spacing of the roots. By running a cross Justin had identified four regional clusters of genes that could be used commercially to select for traits that are best suited for hydroponics.
Meeting customer requirements
Breeding needs to consider:
- Seed performance – ease of production, storage and germination rates
- Growing performance – resistance to mildew, delayed bolting
- Harvesting process and final product – eg pot grown, cut bagged salad, and mixed whole leaves
- Grower – wants to reduce waste and improve diseases resistance
- Retailer – requires consistency of product, availability 24/7 and the opportunity for brand differentiation
- Consumer – wants good shelf life, taste, convenience and a nutritious product that is chemical free. Rocket has proved particularly challenging as the product taste and appearance varies from the first to the second cut
Outdoor baby leaf production; the next chapter of an ever-changing field! – Robert Parker, Leafy Salad Crop Manager, G’s Fresh
G’s are a major producer of salad crops and grows babyleaf in particular locations on the East coast that are cooler and have access to plentiful clean water. It is grown in the field in rotation with other crops such as sugar beet, celery and vining peas.
A point of difference is that the leaves are unwashed and so last longer in the consumer’s fridge – seven days, compared to three. However, it has been found that the benefit has not been appreciated by the consumer.
About 20 per cent of the crop is wasted and nearly half this waste is due to over-supply to meet unpredictable demand, although better forecasting using systems like SpinCam, have halved this waste over the last three years.
G’s is currently investigating how to used controlled environments to increase the growing period within a Innovate UK project with Harper Adams. It is looking at indoor baby leaf production and propagation for whole head production.
Benefits of controlled environment agriculture would be:
- More control over the use of chemicals
- Less risk from disease and soil pathogens
- Greater water security and quality
- Opportunity to increase automation to reduce labour requirements
- Increase the quality and nutritional value of the crop
- Offer new products that are not currently available in the UK
- Year-round production
However there are considerable challenges:
- Price point is a huge issue – for example, in pea shoot production, we can import at 3p a kilo, the cost for indoor is currently closer to £8/kilo
- Logistics – lighting, heat and moisture need careful control
- Location – the facility needs to be close to distribution centres to reduce the cost of transporting ‘bags of air’ across the UK
Innovation in hydroponic and soilless cultivation – Arnoud Witteveen, CTO, Saturn Bioponics
Saturn Bioponics supports soil-less cultivation under diffused light in polytunnels. The result is consistent indoor product in vertical units, without a difference in quality from the top to the lower levels. The stacked system increases the planting density, in strawberries this is six times that of a table top system.
The modular system is developed so that the rootzone can be drained and replacement plants popped in as plugs as required and the system scaled as required. Also different crop types can be grown together.
In blind tests of strawberries with consumer an improved flavour was observed. Saturn sees increasing demand for baby leaf products – increasingly M&S ready meals contain salad and other vegetables and these are high value items.
The Saturn system does not use LED lighting; the diffused lighting and reflective white flooring produces sufficient light for salad crops. However, this could be a consideration for the future.
Light quantity and quality can influence crop performance – Jim Stevens, Postdoctoral Researcher, University of Essex
Jim discussed how with the falling price of LEDs it is now possible to create lighting recipes to influence plant growth:
- Red: far red light can impact the flowering times, which can delay bolting in lettuce. The ratio of red/far red determines the response and also the length of exposure. A longer flash can be used to induce flowering
- Green: this can stimulate stomatal closing, potentially it could be used to reduce water loss from the plant and therefore the requirement for irrigation
- Blue: on its own, blue light can trigger stomatal opening and start the photosynthesis process
- Blue/Red light: this influences the yield and through the impact on volatile compounds the quality of the produce
Jim also described how NDVI, which is a measure of ‘green-ness’ in a plant, can be used to identify its health and provide early warning of a nutrient deficiency.
For more information about Hy4Dense visit www.interreg2seas.eu/en/Hy4Dense
Agri-Tech East will be running a conference “Controlled Environment Agriculture – The Industry is Growing Up” on 18th March at the John Innes Centre in Norwich – more information here.