Comparison of Deficiency Symptom Expression, Growth Response and Nutrient Uptake as Influenced by Ca Fertilization in Two Strawberry Cultivars Used as Diagnostic Tools

Objective of this research was to determine the influence of calcium (Ca) concentration in the fertilizer solution on development of nutrient deficiency symptoms and growth responses in strawberry (Fragaria × ananassa Duch.) 'Keumhyang' and 'Seonhong'. To achieve this, Ca concentrations of above ground plant tissue and of petiole sap were analyzed to compare the nutritional condition of Ca which resulted in decreased crop growth. The Ca deficiency symptoms developed on the young leaves with deformed margin in 'Keumhyang' and severe necrosis and tip-burn in 'Seonhong'. Growth response in fresh weight of 'Keumhyang' and 'Seonhong' to elevated Ca concentrations in the fertilizer solution was quadratic with the greatest fresh weights of 22.42 g in 'Keumhyang' (y=15.88+1.7641x-0.1190x²) and 18.95 g in 'Seonhong' (y=10.80+2.5174x-0.1945x²) per plant at 120 days after transplanting. The Ca concentrations in petiole sap increased lineally with the equations of y=40.01+9.688x in 'Keumhyang' and y=44.34+3.5970x in 'Seonhong'. When the concentration of Ca which retarded plant growth by 10% was regarded as the threshold level, Ca concentration in petiole sap should be maintained higher than 79 mgㆍkg-¹ in 'Keumhyang' and 60 mgㆍkg-¹ in 'Seonhong' to prevent the growth suppression. Growth response of dry weight to elevated Ca concentrations in the fertilizer solution was quadratic with equations of y=3.6926+0.5317x-0.0578x² in 'Keumhyang' and y=1.8121+0.6008x-0.0475x² in 'Seonhong'. Tissue Ca contents responded to elevated Ca concentrations in the fertilizer solution and increased lineally in both cultivars. From these equations, lower critical content of Ca was 1.45% in 'Keumhyang' and 1.85% in 'Seonhong'. From these results, we concludeded that 'Keumhyang' requires higher Ca in the fertilizer solution for optimal growth than 'Seonhong'.