Parashuram Bhantana^a*, Christian Richardt Jensen^b, Fulai Liu^b, Marianne Bertelsen^a and Karen Koefoed Petersen^a

^aDepartment of Horticulture, Faculty of Agricultural Sciences, Aarhus University, Kirstinebjergvej 10, DK-5792 Aarslev, Denmark.

^bDepartment of Agriculture and Ecology, Faculty of Life Sciences, Copenhagen University, Hoejbakkegaard Alle 13, DK-2630 Taastrup, Denmark.

^*Corresponding author Parashuram.Bhantana@agrsci.dk

Abstract

Optimization between yield and fruit quality is essential as growing consumers’ awareness towards longevity and health hazards. Strawberry (Fragaria × ananassa Duch. var. ‘Sonnata’) was grown in peat, irrigated to the maximum transpiration (T_max) of 0.75, 1.00 and 1.25 with K₂SO₄ concentrations having electrical conductivities (EC_iw) of 1.56, 2.55 and 3.94 dS m^-1. Increasing T_max increased fruit yield, first class berry weight, fresh biomass and leaf area but decreased the amount of sugar and acid content in the fruit. Contrastingly increasing EC_iw decreased fruit yield, first class berry weight, fresh biomass and leaf area but increased the amount of sugar and acid content in the fruit. And water use (WU) to evaporation (E_o) ratios in the middle of the strawberry growth period varied from 0.6 to 0.9, which can be used for irrigation scheduling in a greenhouse. Furthermore the drainage water electrical conductivity (EC_dw) increased significantly at 1.25T_max with 3.94 dS m^-1 of K₂SO₄ application although similar values for WU were observed with three different levels of K₂SO₄ treatment. In Denmark, the commercial strawberry growers are practicing a high irrigation amount to receive a high drainage in order to maintain the sum of drainage and irrigation EC equals to three. Such a practice can cause a risk of secondary salinization due to increased accumulation of nutrients and salts in the ground water. Thus, irrigating to 1.00T_max with EC_iw of 2.55 dS m^-1 (5mM of K₂SO₄ addition) can be optimum for the strawberry production under Danish conditions.

Keywords: Strawberry, Fruit quality, Potassium sulphate, Water use, Irrigation scheduling