EFFECTS OF SPRINGTIME FOLIAR FERTILIZATION ON STRAWBERRY YIELD IN ESTONIA

Strawberries (Fragaria x ananassa Duch.) grown in northern areas are subject to various stress factors limiting the attainable yield. The objective of this study was to compare the effects of the foliar application of calcium nitrate on the yield. Foliar fertilisation was performed in order to give additional nutrition during the period of flowering and rapid growth in spring. The experiment was carried out in a production field where cultivars Jonsok, Senga Sengana and Bounty were grown and black plastic mulch and straw mulch were compared. The results showed that the effect of foliar fertilization on strawberry yield depends on the cultivar and mulch (plastic or straw). Foliar fertilization of ‘Jonsok’ plants in a young plantation was effective when there was stress caused by unfavourable conditions in spring. In the case of ‘Bounty’, foliar fertilization was effective on straw mulch. In our experiment in the first year of production there was a strong relationship between the fruit calcium content and incidence of spoiled berries. Spraying ‘Senga Sengana’ plants, susceptible to grey mould, with calcium nitrate during their flowering does not decrease the incidence of spoiled berries.