Outdoor Lettuce: Improving quality and shelf-life of ‘Romaine’ and ‘Iceberg’ crops using precision and deficit irrigation techniques


SummaryThe aim of this project is to develop scientifically-derived precision irrigation (PI), deficit irrigation (DI) and alternate wetting and drying (AWD) regimes that improve consistency of leaf quality and shelf-life potential in Romaine (“Scala”) and Iceberg (“Challenge”) lettuce without reducing head fresh weight. Optimising irrigation scheduling to match demand with supply under changeable UK growing conditions is challenging for many growers. Over-wet soils due to excessive rainfall or ineffective irrigation scheduling can promote postharvest midrib pinking and reduce shelf life in some varieties e.g. Romaine and Iceberg. Anecdotal evidence suggests that lettuce crops grown overseas with reduced water inputs often have better leaf quality and a longer shelf-life than those grown under typical UK commercial conditions. There is evidence that using PI, DI and/or AWD has the potential to improve leaf quality and shelf-life in cut lettuce leaves, but head fresh weights are often reduced by more severe DI treatments. NIAB EMR has expertise in developing and implementing these irrigation techniques and associated technologies to improve on-farm resource use efficiency, marketable yields, quality and shelf-life in several horticulture sectors, including leafy salads and herbs. We will collaborate with the BLSA and Dr Jim Monaghan to help guide the programme of work, to ensure that our methods and conclusions are robust and transferable to other growing systems, and to develop further opportunities for linked RTO-industry projects. Outputs include guidelines to optimise water (and fertiliser) use efficiency and leaf quality in high intensity lettuce crops, and a blueprint for improving production efficiency in other leafy salad crops. 

Benefits to Industry

Lower leaf water content and higher dry matter
Enhanced leaf antioxidant potential
Lowered propensity for postharvest midrib pinking
Assured or extended shelf-life
Reduced pre- and post-harvest waste
Irrigation techniques that will help lettuce growers to demonstrate compliance with legislation
Blueprint for using PI, DI and AWD to improve leaf quality and shelf-life of other salad crops on a range of soil types
Project code:
FV 454
01 April 2017 - 31 March 2018
AHDB Horticulture
AHDB sector cost:
£70, 624
Project leader:


FV 454_Final Report_2018 FV 454_Final Report_2018_GS

About this project

Aims: To improve leaf quality and shelf-life potential in commercial Romaine and Iceberg lettuce crops using precision, deficit and alternate wetting and drying irrigation techniques optimised for different soils.
To derive and test irrigation set points based on soil matric potentials for Romaine and Iceberg  lettuce in a peat and a silt soil
To determine the effects of precision, deficit and alternate wetting and drying irrigation treatments on consistency of lettuce leaf quality
To communicate and demonstrate the results to the industry