Effect of nitrogen form and radiation on growth and mineral concentration of two Brassica species |
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Authors: | C. Fallovo G. Colla M. Schreiner A. Krumbein D. Schwarz |
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Affiliation: | 1. Università degli Studi della Tuscia, Dipartimento di Geologia e Ingegneria Meccanica, Naturalistica e Idraulica per il Territorio (GEMINI), 01100 Viterbo, Italy;2. Institute of Vegetable and Ornamental Crops, Großbeeren & Erfurt e.V., Theoder Echtermeyer Weg 1, D-14979 Großbeeren, Germany |
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Abstract: | Three greenhouse experiments were carried out to determine the growth, yield, nitrate, total N and S concentration in shoots, and water uptake of hydroponically grown Brassica rapa L. subsp. nipposinica var. chinoleifera and Brassica juncea L. In each experiment, daily photosynthetically active radiation (PAR) level was 5.0 mol m−2 (low), 6.8 mol m−2 (medium) or 9.0 mol m−2 (high). Plants were supplied with nutrient solutions having equal N concentrations of 11 mM in different forms: 100% NH4, 50% NH4 + 50% NO3, and 100% NO3. Nitrogen supplied as 100% NH4 reduced fresh and dry shoot biomass, leaf area, and leaf number in both Brassica species, especially at low and medium PAR levels. In both Brassica species, S concentrations were highest, while nitrate concentrations were lowest in leaves of plants grown at N supplied as 100% NH4. No differences in leaf nitrate concentrations were observed between 50% NH4 + 50% NO3 and 100% NO3 treatments. Low and high PAR levels increased the nitrate concentrations and decreased the N/S ratio in leaves of both crops compared to medium PAR level. Fresh shoot biomass was maximized in Brassica rapa when PAR level was above the medium value and nitrate was supplied in the nutrient solution as NO3 or as a mixture of 50% NO3 and 50% NH4. The highest fresh shoot biomass of Brassica juncea was observed in all nutrient solution treatments at high PAR level. |
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Keywords: | Brassica rapa L. Brassica juncea L. Hydroponics Nitrate Ammonium Photosynthetically active radiation (PAR) |
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