Potassium-calcium ratio of the nutrient solution: implications for fruit quality in June-bearing and day-neutral strawberry cultivars

The aim of this trial was to determine the implications for fruit quality in strawberries grown on substrate at different K:Ca ratios. Four June-bearing cultivars ('Malling Centenary', 'Magnum', 'Opera' and 'Jive') and four day neutral cultivars (selection number '08-06-10', 'Eve's Delight', 'Murano' and 'Harmony') were grown in plastic tunnels on raised gutters. Plants were given nutrient solutions with either a high (7:2 mmol L-1), standard (5:3 mmol L-1) or low K: Ca ratio (4:3 mmol L-1). Assigned nutrient solutions were given continuously from flowering until the end of harvest. Fruit colour, seed positioning, fruit firmness, Brix and shelf life were routinely assessed. A high K:Ca ratio for both 'Murano' and 'Harmony' led to more fruit with embedded achenes. A low K:Ca ratio in the nutrient solution led to an increased browning of the fruit skin around the achenes in June-bearing cultivars 'Opera' and 'Jive' and also day neutral cultivars 'Murano' and '08-06-10'. There was no difference in 'Eve's Delight'. In all cultivars a higher K:Ca ratio increased fruit firmness, Brix and improved shelf life. These results show that a high K:Ca ratio improves fruit quality and shelf life in strawberries.