EFFECT OF SUBSTRATE TYPE AND NITROGEN FERTILIZATION UPON YIELDING AND CHEMICAL COMPOSITION OF „ELSANTA” STRAWBERRY CULTIVAR GROWN IN UNHEATED FOIL TUNNEL

Abstract

The main factors determining the quantity and quality of the yield of plants grown in the soilless system is the kind of cultivation substrate used and the level of supplying the plants with nutrients. Studies conducted in the years 2005–2006 were aimed at determining the effect of substrates (peat, peat mixed with pine bark in the proportion of 1:1, peat with pine sawdust in the ratio of 1:1), as well as of differentiated nitrogen dose (140 and 210 mg N·dm-3) upon yielding, chemical composition of strawberry (Fragaria × ananasa Duch.) leaves and fruit, cultivar 'Elsanta’, grown in unheated foil tunnel. In those studies no significant differences were found in total and marketable yield of strawberry fruit grown in peat, as well as in peat with pine bark. Significantly smaller total 435.8 g·plant-1) and marketable (286.5 g·plant-1) fruit yield was reported when strawberries were grown in peat mixed with pine sawdust. In plants grown in peat mixed withsawdust significantly smaller fruit unit weight (10.7 g) was found, as compared to plants that grew in the remaining substratums. In our studies no significant effect of differentiated nitrogen fertilization upon strawberry yielding was demonstrated. In the leaves of strawberries fertilized with nitrogen in the dose of 210 mg N·dm-3 we found significantly more nitrogen and phosphorus, as well as less calcium and magnesium, as compared to plants fertilized with smaller doses of this nutrient. The fruit of strawberries fertilized with a higher nitrogen dose contained significantly more nitrogen and potassium, as well as less vitamin C and soluble solids, as compared to the fruit collected from plants fertilized with nitrogen in the dose of 140 mg N·dm-3