Magnesium Status in Corn (Zea Mays L.) Hybrids and Its Relations to Potassium and Calcium

Twenty corn (Zea mays L.) hybrids were grown under the field conditions during the 2000 and 2001 growing seasons. The ear-leaf at the beginning of the silking stage was taken for chemical analysis. The experimental fíeld was acid hydromorphic soil with moderate levels of mobile fractions of magnesium (Mg), calcium (Ca) and phosphorus (P). In our testing considerable influences of growing season (mean 0.273 and 0.177 mg Mg/kg, for 2000 and 2001, respectively) and heredity (range of 2-year means among the 20 hybrids: from 0.120 to 0.291 mg Mg/kg) were found. Three corn hybrids (OsSK395, RK1456 and OsSK332) had low Mg (<0.2000 % Mg) concentrations in both growing seasons (means 0.177 and 0.138 % Mg, for 2000 and 2001, respectively). Four other hybrids (OsSK277, OsSK2-91, OsSK247 and OsSK234) had adequate Mg status (means 0.297 and 0.228 %, for 2000 and 2001, respectively). Grain yields of the hybrids ranged from 4.06 to 11.691 ha-1. Six hybrids yielded less than 7 t hal (Alpos, OsSK2-191, OsSK247, Bc278 and Clarica: mean 5.491 ha-1. Yields of other three hybrids were above 10 t ha-1 (OsSK378, OsSK298 and OsSK277: mean 10.91 t ha-1). Mean yields of two hybrid groups differing in Mg status totaled 8.60 and 7.521 ha-1, for the low Mg-group and high Mg-group, respectively. Although Mg status in soil and plant was mostly either moderate or low, correlation coefficients between the yield and Mg status were low under these conditions.