Optimizing radish (Raphanus sativus L.) production through alternative nitrogen sources

Radish is a tuberous vegetable rich in nutrients, making it a great option for crop rotation on small and medium-sized properties. In this way, the determination adequate sources and doses of nitrogen (N) is essential to guarantee the development of this crop without excessive losses through leaching, reducing both damage to the environment and production costs. Thus, the objective of this study was to evaluate the growth and physiology of radish cultivated under fertilization with different sources and doses of N. The experiment was carried out in a greenhouse located in the experimental area of the Biotechnology and Plant Breeding Sector of the Department of Biosciences of the Center for Agrarian Sciences, Federal University of Paraíba, Areia, Paraíba, Brazil. The experimental design was in randomized blocks in a 2 x 5 factorial scheme (two sources of nitrogen fertilization - urea and ammonium sulfate; and five doses of nitrogen fertilizer - 0, 15, 30, 45 and 60 kg ha-1) with four replications. Plant height, fresh and dry mass of roots, fresh and dry mass of shoots, number of leaves, leaf area, gas exchange, chlorophyll index and chlorophyll fluorescence were evaluated. Radish growth was positively influenced by N sources and doses. The application of urea was more efficient for plant growth, chlorophyll a index and total chlorophyll index, and fertilization with 15.0 kg ha-1 of urea was the most efficient way to increase the growth and production of radish plants.