MINERAL CONCENTRATIONS IN LEAF DRY MATTER AND LEAF AND PETIOLE SAP IN STRAWBERRY DEPEND ON LEAF AGE AND PLANT DEVELOPMENTAL STAGE

Abstract

Analysis of leaf dry matter is valuable when assessing the plants nutritional status, and for fertilizer evaluations in perennial crops. Methods for analyses of strawberry leaf and petiole sap have now become available, aiming to measure the concentration of inorganic nutrients in sap rather than the concentration of all nutrients accumulated in leaf dry matter. The use of fertigation systems and the possibilities to change fertilizer application rates at any time during the season, suggest that leaf sap analysis may become a useful tool in precision fertilization in strawberry. The present field trial aimed to provide information on variation in leaf and sap nutrient concentration during the season in the strawberry cultivar Korona. Young and unexpanded leaves, youngest fully expanded leaves and old leaves were sampled at defined plant developmental stages in the first and second harvest year. Both leaves and petioles were used for sap analyses, while only the leaf lamina was used for dry matter analysis. A constant fertilizer rate was applied through the drip irrigation system from May to August, but the results demonstrated a large variation in the concentration of mineral elements in both dry matter and sap due to differences between leaf ages, time in the season or plant developmental stage. Leaf sap analyses may offer an improved description of the actual nutrient uptake for some of the minerals during the season, if further developed and standardized. Nutrient remobilisation in the plant, dry matter accumulation and plant part analysed should be considered.