EFFECT OF EXTRA POTASSIUM SUPPLY ON CORN YIELD AND SEED QUALITY UNDER DEFICIT IRRIGATION CONDITIONS

Deficit water treatment studies and some practices to reduce the effects of drought on plant can be made in Mediterranean region. Therefore the study was carried out at 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 (NH4NO3, P2O5 and K2O - 60 kg.ha(-1) 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 Tasselling (VT), after blister, milk stage and dough stage)] in the Aegean region of Turkey during 2013 summer growth periods. The experiment was a randomized block design with three replications. 31G98, 31D24 and NK-Arma corn cultivars were used to material of the experiment. Seed yield and some yield components such as cob length, the number of seed per cob and 1000 seed weight were measured. Additionally some seed quality traits such as oil content, protein content, starch content, ASH and cellulose contents of corn seed were also measured in the study. The results of this study showed that extra potassium supply was effected on seed yield, the seed number in corncob and ash and cellulose contents of corn seed positively. However 1000 seed weight, corncob length, oil, protein, starch contents of corn seed didn't effect or negatively affect with extra potassium supply. It was revealed that seed yield, 1000 seed weight, oil and starch contents of corn seed were decreased with deficit water treatments (300 mm and 400 mm) according to standard water treatment (500 mm). In contrary that cob length, the number of seed per cob, protein, ASH and cellulose contents of corn seed values does not give similar responses (increasing or decreasing) with deficit water treatments. The highest seed yield was obtained from 31G98 corn cultivar in standard irrigation dose (500 mm) and extra potassium treatment because of having high thousand seed weight. As a result of the experiment, it was suggested that extra potassium treatment should increase yield and some properties of corn but only extra potassium isn't exactly effective against negative effects of drought.