engleski

Response of Maize Genotypes to Potassium Deficiency on Strong K-Fixing Soil

Retardation of growth and chlorosis appeared at maize juvenile stage on some soils of Croatia when ordinary fertilization practice was applied. As strong K-fixation in soil and K deficiency in plant were found by laboratory test, field trials with increased K fertilization were conducted (Kovacevic 1994). Also, different degree of maize hybrids tolerance to soil stress was observed. For this reason, three field trials were conducted in four replicates on typical plot of properties as follows: pH in KCl = 7.19 ; exchangeable cations by 1mol/l ammonium acetate (pH 7) extraction (mg/100 g of soil) = 7.0 K, 145 Mg and 1506 Ca. The exp. 1. Twelve maize inbred lines were grown during the growing season of 1990 (exp. plot 7.0 m2 ; plant density 71400/ha). The ear-leaf (silking stage) composition (on dry matter basis) was as follows: from 0.37% to 0.75% P, from 0.38% to 0.59% K (acute K deficiency) and from 1.50% to 2.0% Mg (excess of Mg). Also grain yield differences (g/cob on 14% moisture basis) ranged from 10.6 to 29.3 and stalk lodging at maturity stage from zero to 90%. Differences of grain yields are impossible explain by the ear-leaf nutritional status, probably because acute K deficiency and Mg excess were found in all tested inbred lines (Kovacevic and Brkic 1994). The exp. 2. Fourteen maize hybrids (group A = seven hybrids contained Os1-48 inbred line as male parent ; group B = seven hybrids contained Os87-24 inbred line as male parent) were grown during the growing season of 1990 (exp. plot 7 m2, plant density 71400/ha). The hybrid of group A had considerably lower percentage of stalk lodging and higher grain yields (mean 4.9% and 5.64 t/ha) compared to group B (59.1% and 4.16 t/ha). These properties are closely connected with the composition of stalk base at maturity stage (comparison of groups A and B) as follows (in dry matter): 0.53% Mg and 0.72% Mg, 0.24% K and 0.19% K, respectively (Kovacevic and Vujevic 1994). However, under normal soil conditions (absence of K deficiency as factor promoting lodging incidences), hybrids of group A are satisfied tolerant to stalk lodging. The exp. 3. Six maize hybrids were grown during the growing season of 1993 (exp. plot 18.2m2). Role of inheritance factors on soil stress tolerance are very expressed (Table 1). For this reason, choice of more tolerant hybrids as well, modified fertilization practice (high doses of K application) is the main directions of normalization of maize nutrition in these soils. Table 1. Response of maize hybrids to soil stress induced by K deficiency (Kovacevic et al. 1996) Maize Grain yield Stalklodging PDR Grainmoisture The ear-leaf status (% in dry matter) at silking stage hybrid (t/ha)* (%) (%)** (%) K Mg Ca P OsSK377OsSK382OsSK407OsSK552OsSK644Bc 66-61 2.472.141.781.461.601.54 475421171114 68.467.275.366.259.171.1 30.723.336.933.641.738.5 0.370.330.300.310.300.26 1.160.921.071.081.101.15 0.990.830.980.920.861.06 0.800.560.620.550.590.72 LSD 0.05LSD 0.01 0.480.63 0.070.09 0.050.07 0.050.07 0.040.05 * calculated on 14% moisture basis and realized plant density with correction for share of female-sterile plants ** PDR = plant density realization: 100% = 68027 plants/ha (OsSK377), 63492 (OsSK 382, OsSK407, OsSK552) and 54945 (OsSK644 and Bc66-61)

maize genotypes; potassium deficiency; strong k-fixing soil

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