The effect of differentiated nitrogen fertilization on nitrate reduction in broccoli heads of Lord F1 in spring cultivation
2006
Wojciechowska, R. | Rozek, S. | Leja, M.,Krakow Agricultural University (Poland). Dept. of Plant Physiology
Broccoli (Brassica oleracea L. var. italica) Lord F1 was grown at the Agricultural University experimental farm in the Cracow area in the spring growing cycle of three successive years. In harvested broccoli heads activities of nitrate reductase (NR) and nitrite reductase (NiR) as well as NO3- and NH4+ ions contents were determined. The nitrogen fertilizer rate introduced into the soil did not significantly affect the average activity of both enzymes, responsible for nitrate reduction. The application of mineral N increased nitrate level in broccoli heads, however, decreased NH4+ content. The foliar nutrition with 2 percent urea, applied five times during the growing period significantly increased the activity of NR in all investigated treatments, but did not influence the activity of NiR as compared with non-fed plants. Foliar application lowered the average nitrate content in broccoli heads but the significant effect was found only in the case of the full rate of mineral N. This factor did not significantly affect ammonium ions content in the analysed plant organs. Strong interdependence was observed between the activity of the determined enzymes, as well as of NO3- and NH4+ and the weather conditions accompanying the plant cultivation in the particular years of experiment
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