RECIRCULATING NUTRIENT SOLUTION IN STRAWBERRY

The nutrient solution in closed systems accumulates toxic ions and increases the EC during the long time of growing, both of these processes are harmful for strawberry, which is very sensitive. Strawberry response to leachate recycling in greenhouses has not been studied yet in Spain. The objectives of this work was to examine the effect of recirculating nutrient solution, determining strawberry response to temporal salinity and specific ion accumulation in recycled greenhouse leachates, it was using two different types of organic substrates like peat and cork composted, also it was tested with the open system in each substrate. The closed system was combined with slow sand filtration for disinfestation of the recirculated nutrient solution. This experiment was carried out from October to May in 2002. Substrates were filled into horizontal throughs as 10 l per m2. Camarosa^® plug plants were planted the 5^th of October and the density of plantation was 11 pl/m². Cl^-, Na⁺ and SO₄^2- were considerably increased (between 115 and 170 %), concentrations upper 8 mmol of Cl^- and Na⁺ were found in lixiviates. H₂PO₄^- and NO₃^- presented different behaviour between peat and cork. Possibly, cork was not sufficiently composted and the consumption of H₂PO₄^- and NO₃^- was upper than peat. Cork presented a high alkaline reaction which produced problems with micronutrients, overall Fe, generating clorotic leafs in closed systems. Yield was not affected by recycling. There were not significant differences between open (5,91 and 5,4 kg/m² for peat and cork respectively) and closed systems (5,56 and 4,17 kg/m² for peat and cork respectively) in respect to total yield. The peat gave the highest yield among the tested substrates in each system. Recirculation is possible and it does not present a great problem for growing strawberry in soilless, however it is necessary adjust multiple factors of this system which will improve the yield.