Content of macro- and micronutrients in chitosan treated freesia (Freesia Eckl. ex Klatt) leaves

Freesia grown under cover to be marketed as cut flower is highly sensitive to substrate temperatures exceeding 15–18°C. However, freesia varieties of Beach group are especially attractive plants that may be easily cultivated under cover and do not require substrate cooling. Experiments were conducted in summer and fall of 2011 and 2012 in an unheated plastic tunnel. Planting material consisted of daughter bulbs of ‘Summer Beach’ freesia. The plants were treated with chitosan with a molecular weight of 8000 g∙dm–3. Experimental variants involved methods of chitosan application (watering vs. spraying), its concentration (0.2 vs. 0.4%) and frequency of application (7 vs. 14 days). During the flowering period and at the end of vegetation, freesia leaves were collected to determine the content of following micro- and macronutrients: N, P, K, Ca, Mg, Zn, Cu, Mn, and Fe. The leaves collected at the end of vegetation season contained more P, K, Ca, Fe, Mn, and Zn than those collected during flowering. The content of Mg and Cu was similar in both cases, but N level was lower at the end of vegetation. Irrespective of experimental variant, leaves of all plants treated with chitosan accumulated more N, P, Ca, Cu, Fe and Mn and less Zn during the entire vegetation season than the control ones. At the end of the vegetation season, plants sprayed with chitosan revealed higher concentration of N, P, Ca, Mg, Fe, and Zn, and lower concentration of K, Cu, and Mn than those watered with the investigated compound. No clear patterns of micro- and macronutrient accumulation depending on chitosan concentration were observed. Plants treated with 0.2% chitosan contained more P, K, Mg, Mn, and Zn than those exposed to its two times higher concentration. A contrary response was observed for the leaf accumulation of N and Fe.