Effect of Nitrogen Form and Type of Polyethylene Film Covering Tunnel on Nutrient Content of Hydroponically Grown Sweet Pepper

The effect of nitrogen form (nitrate or nitrate-ammonia-amide) and a type of polyethylene film (two types, differing light transmission, light dispersion and PAR) covering a tunnel on the content of macroelements in the leaves of sweet pepper being in different stages of growth were studied. The plants were grown in rockwool slabs, using a drip fertigation system without recirculation. In each part of the tunnel there were two sets of cultivation gutters independently supplied with nutrient solution containing different forms of nitrogen: nitrate (100% N-NO3), nitrate-ammonia-amide (50% N-NO3, 13% N-NH4, 37% N-NH2). Dry matter and mineral composition were determined in the leaves with petioles. The leaves were collected in three stages of growth, e.g. intensive vegetative growth, flowering and full fruiting. The plants fed with nitrate N form contained more Ca and Mg, irrespective of a type of polyethylene film and stage of growth. N form had no effect on K content, except in plants being in flowering. In all stages of growth, irrespective of a type of polyethylene film, the plants fed with nitrate-ammonia-amide N form accumulated more N. The effect of a type of polyethylene film covering a tunnel on nutritional status of the plants being in stage of intensive vegetative growth or flowering was not univocal. However, in fruiting chemical composition, except N content in year 2007, did not depend on a tunnel part.