Significant Water Savings Can Be Made In Commercial Spinach Cropping Without Adverse Impacts on Crop Yield or Shelf Life

Spinach (Spinacia oleracea L.) is grown extensively across the globe but requires irrigation to maintain both yield and leaf quality. Water resources are being put under increasing pressure as we endeavour to produce enough food, fuel and fibre for a growing human population. Thus, improving our water use efficiency is becoming ever more important. Here, we report the impacts of excess and deficit irrigation on spinach yield and quality. Mild deficit irrigation (-18% of commercial water application) had no significant impact on crop quality indicators or yield, with a trend for improved shelf life, when compared to the commercially irrigated crop. Alongside this, yield was only improved when water was applied in 40% above commercial levels. The yield and quality maintenance observed under mild water deficit was associated with a reduced stomatal index suggesting a useful trait for future breeding for drought tolerance. If this relationship is robust across environments and crop varieties, major water savings will be possible across the leafy salad agricultural sector, reducing the water footprint and improving the sustainability of crop production. Furthermore, this research has elucidated links between plant responses to irrigation modifications and the thermal spectra of the canopy, with the canopy range of temperature being the most sensitive indicator of soil moisture. There is potential for these relationships to be further developed across seasons and crops for use in future irrigation decision-making.