Published in Scientific Papers. Series A. Agronomy, Vol. LXI, Issue 1
Written by Yakup Onur KOCA

The study investigates the influence of extra potassium application and deficit irrigation on amino acid composition of corn seed. The field experiment was conducted with split plot design with three replications in Aydın location of Turkey in 2013. Parcels of the experiment was established with three different supplies as non-fertilization, standard fertilization [210 kg.ha^-1 pure N, 60 kg.ha^-1 pure P, 60 kg.ha^-1 pure K, 60 kg.ha^-1 (NH₄NO₃, P₂O₅ and K₂O with 15-15-15 composite before planting and H₂NCONH₂ - 150 kg.ha^-1 with urea before first water)] and extra potassium (standard fertilization +60 kg.ha^-1 K₂SO₄) and three irrigation doses (500 mm, 400 mm and 300 mm) during development stages [(8 leaf stage (V8), before Tasseling (VT), after blister, milk stage and dough stage)]. 31G98 corn variety, identified as having the highest yield in previous our paper published Scientific Papers Series A. Agronomy, was used. Amino acids rates (essential, conditionally essential and non-essential) of the corn seeds obtained from the different treatments parcels were measured with HPLC. According to the results of the experiment, significant differences among treatments and irrigation doses were found. Almost all essential amino acids were increased with standard fertilization and extra potassium supply compared to non-fertilization. Just methionine and threonine in this group were irregular with these treatments. Similarly, almost all essential amino acids values except for histidine, valine and phenylalanine were increased with 400 mm compared to 300 mm, whereas these groups were decreased with 500 mm irrigation dose. As for conditionally essential and nonessential amino acids, glutamic acid and serine were increased with standard fertilization while were decreased with extra potassium supply. Contrary to glutamic acid and serine, glycine was decreased with standard fertilization while was increased with extra potassium supply. The other amino acids in the group were increased with both standard fertilization and extra potassium supply compared to non-fertilization. In terms of irrigation doses, tyrosine and serine values were increased with raising irrigation doses. Proline, arginine, aspartic acid and glutamic acid were increased with 400 mm compared to 300 mm, whereas the amino acids were decreased with 500 mm irrigation dose.

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