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Influence of genotype and potassium on sulphur status in maize plants

In general, maize and other cereals are moderate needs for sulphur and mostly there are adequate sulphur levels in nutrient medium for their normal growth. However sulphur deficiency is increasing throughout the world as a result of decreased use of S-containing fertilizers, intensive cultivation, use of high-yielding varieties, and use of S-free fungicides.. For this reason, we presume that in near future, sulphur could be more limited factor of plant nutrition, even those plant species of moderate needs for S. There are evidence that maize responded to S fertilization. Beaton (1980) reported that maize grain yield increased for 18% (mean of 19 field trials in six states of USA) as affected by S application. Also, under Indian conditions (Tandon 1995), maize grain yields were increased for about 40% (mean of three studies), while wheat grain yields for about 25% (mean of 32 studies). As plant nutrition is under influences both environmental and inheritance factors, we tested plant sulphur status (the ear-leaf S concentrations at beginning of the silking stage) of six maize hybrids which were grown under identical environmental conditions (the field trial of increased K fertilization on strong K-fixing soil). Six maize hybrids (OsSK377, OsSK382, OsSK407, OsSK552, OsSK644 and Bc66-61) were grown under field conditions (four replications, exp. plot 18.2 m2 ; the growing season 1993) and four levels of muriate of potash (KCl containing 60% K2O), which were applied three year ago (1990) in the quantities as follows:: 150, 1000, 1900 and 3250 kg K2O/ha - exp. plot of fertilization 294 m2 ). Soil is classified as drained gleysol developed on calcareous loess. It is characterized by strong K fixation and oversupplies of Mg and Ca. By soil testing (depth 0-30 cm ; NH4-Acetate/EDTA extraction), we found quantities of nutrients as follows (mg/kg): 51390 Ca, 1482 Mg, 102 K and 63 S. The ear-leaf at beginning of the silking stage (middle of July 1993) was taken from each plot (25 leaves in mean sample) for chemical analysis. Plant sulphur status were determined by ICP technique in the Research Institute of Soil Science and Agricultural Chemistry, Budapest. The ear-leaf S status were under considerable influence of inheritance factors. For example, in the Os382 hybrid it was found about one third higher S concentration compared to Os407 hybrid (Table 1). In general, low connection was found between plant S status and grain yield probably because of adequate soil S status. The most influencing factor of grain yield was K fertilization because of specific soil stress induced by K deficiency. However, K fertilization negatively influenced on the ear- leaf S status in maize: they were in mean about 23% lower compared to control as affected by the highest rate of K fertilization. Also, PDR (Table 1) values were considerable lower under soil stress conditions induced by K deficiency. Table 1. Influences of hybrids and K fertilization on the ear-leaf (the beginning of the silking stage: middle of July 1993) S status (on dry matter basis) and grain yields of maize Influence of factor hybrid (means of four K doses)Influence of factor K fertilization (means of six hybrids) HybridGrain yield (t/ha)* PDR (%)**The ear-leaf S status (mg S/kg) kg K2O/haGrain yield (t/ha)* PDR (%)**The ear-leaf S status (mg S/kg) OsSK377 OsSK382 OsSK407 OsSK552 OsSK644 Bc 66- 614.60 4.99 5.31 4.95 4.70 4.3576.7 80.5 93.1 87.3 77.5 85.41861 2063 1552 1859 1722 1908 150 1000 1900 3250 1.83 4.08 6.32 7.04 67.9 82.4 89.8 93.6 2104 1862 1737 1620 LSD 0.050.24780.44113 * 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) References: Beaton J. D. (1980): Sulphur: One key to high yields in small and coarse grains. Solutions, 24, No 6, 16-33. Tandon H. L. S. (1995): Sulphur in Indian Agriculture: Update 1995. Sulphur in Agriculture , vol. 19. p.3-8.The Sulphur Institute, Washington, DC, USA.

genotype ; potassium ; sulphur ; maize

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