Influences of Ameliorative Fertilization on Yields and Status of Harmful Metals (Cd, Sr, Pb, Cr And Ni) in Corn Plants

摘要

Two identical field experiments were conducted in spring 2001 on two hydromorphic soils of moderate fertility (the soil Ⅰand the soil Ⅱ, for Malino and Kobas locality, respectively) in Brod-Posavina County, the eastern Croatia. Increased rates of P and K fertilizers were applied two weeks before sowing on ordinary fertilization as follows: a) control (standard fertilization); b) a + 750 kg P_2O_5/ha; c) a + 1500 kg P_2O_5/ha; d) a + 750 kg K_2O/ha; e) a + 1500 kg K_2O/ha; f) = c + e. Monoammonium phosphate (MAP: 12% N + 52% P_2O_5) was source of P, while potash used as a source of K. The field trials were conducted in four replicates. Experimental plot of fertilization measured 64 m~2. In each plot of fertilization were grown three corn hybrids (OsSK444, OsSK552 and Bc5982). Gross of plot of corn hybrids was 28 m~2. The leaves samples (the ear-leaf at beginning of silking stage: the second decade of July) were taken for chemical analysis from two corn hybrids (OsSK444 and OsSK552) and four treatments (a, c, f, and e). Concentrations of the harmful elements (Cd, Sr, Pb, Cr and Ni) were determined by ICP-AEC technics. Significant influences of applied fertilization on grain yields were found only on the experiment Ⅰ (grain yields in t/ha): 7.63 (a), 7.94 (b), 8.97~(**) (c), 7.28 (d), 6.91~* (e) and 9.34~(**) (f). Mean yields of corn hybrids in this experiment were as follows (t/ha): 8.48~(**) (OsSK552), 7.82 (OsSK444) and 7.74 (Bc5982). In general, the concentrations of Sr, Cd, and Ni in the ear leaves at silking stage of corn were significantly higher under conditions of the soil Ⅰ (22.5 ppm Sr, 0.361 ppm Cd and 0.284 ppm Ni, compared to 16.8 ppm Sr, 0.217 ppm Cd and 0.154 ppm Ni, respectively). Applied fertilization had not effects on Pb and Ni concentrations in corn leaves. However, using of ameliorative quantity of P fertilizer resulted by increase of Sr and Cr (26.5 and 19.8 ppm Sr, as well 0.30 and 0.25 ppm Cr, for the c and a treatments, respectively), while Cd concentrations in corn leaves increased as affected by both MAP and potash and fertilization (0.25 ppm Cd for the control and mean 0.31 ppm Cd for the c, e and f treatments, respectively). By comparison of the ear leaves composition of tested two corn hybrids were found significant differences of Sr, Cd and Cr concentrations. For example, the OsSK444 hybrid characterizing lower Sr as well higher Cd and Cr levels in comparison with the OsSK552 hybrid (17.9 and 21.4 ppm Sr, 0.315 and 0.263 ppm Cd and 0.299 and 0.254 ppm Cr, for OsSK444 and OsSK552, respectively), while Pb and Ni status were similar in both hybrids (about 0.50 ppm Pb and 0.22 ppm Ni). In general, by our study was found non-toxic levels of tested elements in corn leaves and it is indication of clear environment.