14TSB_ATC_IR: Use of AMF and PGPR in soil-less substrate strawberry production to increase resource use efficiency and fruit quality

This proposal focuses on increasing the yield and ensuring fruit supply from strawberry production. To avoid soil borne diseases, nearly 40% of strawberry production (ca. £90M in values) is grown in soil-less substrate under protection where nutrients and water are better controlled according to the crop requirement. This proposal addresses the efficient use of such resources, the management of which is recognised as one key driver in the delivery of sustainable intensive agriculture. Recent evidence suggests that under a substrate production system with standard fertigation, arbuscular mycorrhizal fungi (AMF) can increase strawberry yield. The present proposal investigates whether application of AMF and PGPR (plant growth promoting rhizobacteria) products in commercial substrates will result in increased resource use efficiency, fruit quality, and tolerance to powdery mildew over different combinations of cultivars.

This proposal focuses on increasing the yield and ensuring fruit supply from substrate strawberry production. To avoid soil borne diseases, nearly 40% of strawberry production is grown in soil-less substrate under protection where nutrient and water are better controlled according to the crop requirement.

Past research on AMF and PGPR has focused on their ecological function in soil. However, application of arbuscular mycorrhizal fungi (AMF) and plant growth promoting rhizobacteria (PGPR) products directly into soil is open to debate because there are already resident AMF and PGPR populations present. The positive effect of AMF is usually explained in terms of increased nutrient (particularly P) and water uptake. However, recent unpublished data at East Malling Research suggested AMF can improve strawberry yield in coir substrate under conditions where its perceived role in nutrient and water uptake is not likely to explain their effect. If the positive effect on fruit yield and quality is confirmed on a range of strawberry cultivars and substrate types, AMF and PGPR products may be considered as an essential part of substrate production where their application is easier than under field cropping systems.

This proposal will develop new biological products based on AMF and PGPR to amend the substrate in order to improve resource use efficiency, as one of key drivers in the delivery of sustainable intensive agriculture. Specifically, EMR will conduct experiments to (1) determine whether AMF and PGPR could improve fruit production and quality, and increase plant tolerance to powdery mildew on a range of strawberry cultivars and substrate types, (2) determine (and quantify) the nature (synergistic, additive or competitive) of interaction between AMF and PGPR products in affecting strawberry production in substrate, and (3) elucidate possible biological mechanisms that underpin the effects of AMF and PGPR on strawberry in substrate production.

Strawberries are an economically important soft fruit with many health benefits, representing a successful and expanding industry worth £220M per annum in the UK (ca. two thirds of the total UK consumption). To eliminate the risk of Verticillium wilt in soil production and to extend season, nearly 40% of strawberry is now produced in substrate (such as coir) under protection where irrigation and fertilizer input is well controlled. The main challenge in such a production system is how to improve resource use efficiency (water and fertiliser) while maintaining, or even increasing, yield and quality. As a consequence of production under protection, powdery mildew becomes the number one disease, necessitating frequent interventions (often fungicides).
This project will provide practical solutions to increase resource use efficiency in substrate strawberry production. A key outcome of the project will be commercialised AMF and PGPR products for use in substrate strawberry production. An increase 10-15% of fruit yield as observed in preliminary trials would result in fruit production equivalent to £22M to £33M, which is very important for the UK since home production only accounts for two-thirds of the national consumption. Furthermore, the project results will also lead to increased resource (water, fertiliser and fungicide) efficiency - a key driver for sustainable intensive agriculture.
In addition to products/knowledge that are directly exploitable in commercial horticulture, this project will generate basic/strategic knowledge underpinning the use of these products in practice and may lead to future research and development opportunities. In parallel to AMF and PGPR product development and trialling, further research will be conducted at EMR to understand the physiological basis of increased plant growth and yield due to AMF and PGPR applications in substrate through genomics study (RNA-seq) and profiling of plant hormones. Such knowledge may assist us in (1) developing new AMF and PGPR products, (2) assessing potential benefits of these products in other crops in substrate in relation to specific conditions (or stress factors), and (3) understanding possible interaction of these products with other husbandry practices.
In summary, the project will deliver technology that will be highly welcome by the industry because it will increase strawberry production efficiency and contribute to sustainable intensive agriculture. An understanding of AMF and PGPR in affecting plant growth in a substrate production system will also help us to extrapolate the project results to other similar cropping systems, including tomato and cucumber.