INFLUENCE OF CHEMICAL FERTILIZATION ON STRAWBERRY FRUIT PRODUCTION

The nutritional control of strawberry is very difficult, because a large number of factors influence the absorption and availability of nutrients through mechanisms that are not fully understood. Aim is to establish concrete measures for improving crop technology by applying optimum dose of fertilizers, leading to increased productivity and fruit quality of strawberry culture. The research was conducted during 2009-2011, in a two-way experience. It was located at the Institute of Research - Institute for Fruit Growing Pitesti. Experimental factors were: A - cultivars: a1 - Onebor, a2 – Real, a3 - Elsanta a3, a4 - Magic, a5 - Alba, a6 – Premial; a7-Queen Elisa; B – Fertilizer with 6 graduations: b1 - unfertilized, and five graduations b2 - b6 were applied mixtures of the below fertilizers, thus: b2 - 6.4 kg/ha/week, b3 - 14.3 kg/ha/week, b4 - 21.4 kg/ha/week, b5 - 28.5 kg/ha/week and b6 - 35.8 kg/ha/week. The fertilizers applied were: Polyfeed (N19: P19: K19), potassium nitrate (N12: P0: K43: Mg2) and Magnisal (N11: P0: K0: Mg15). Mixtures were applied at 2 weeks intervals, as follows: 1 April to 15 May (flowering time), 2 applications, containing macroelements N: P: K: Mg - 14:6,3:20,7:5,7 g/100 g mixed fertilizers; May 15 - June 15 (in the picking period), 2 applications of N: P: K: Mg 10,2:6,3:13,5:2,83 g/100 g blend fertilizer and August 1 to September 15 (2 applications) with N: P: K: Mg 12,2:6,3:20,7:31,6 g/100 g mixed fertilizers. Following determinations were made: number of fruit per plant, average weight of fruit (g) by weighing a sample of 250 fruits and production in tons/hectare. Experimental treatments have led to differences in fruit production. Thus, the analysis of fertilizer doses on the chemical components of the fruits of the seven studied cultivars, we concluded that V5 and V6 treatments had a positive influence on number of fruit per plant and on yielding capacity. Treatments induced also, highest average fruit weight in variety Queen Elisa (20.61 g).