EFFECT OF SOWING DEPTH AND SEED CALIBRATI ON ON THE MAIZE YIELD

Determination of a sowing depth of crop was in fact always only approx imate of some optimum value of a sowing depth concerning the concrete conditions, approximate level of a determination of this depth and its practically uncontrolled variability remains one of the open problems of the field crop culture. Some results from a corresponding field tr ial with the calibrated maize seed were applied to study the effect of deviation - change in sowing depth. This seed was sown in applying a special simple technique precisely into three depths according to thre e sowing dates and 1000-kernel weight to compare the effects of the ch anges in sowing depth and date and the change of the growing year (thr ee years). The effects of these sources of variability were pursued in the variability of a stand sprouting course, a final state of this em ergence and the yields. It is possible to create a general image of th em by studying a survey in Tab. II. Influencing the stand sprouting co urse and also occasionally the final stand sprouting course and also o ccasionally the final stand sprouting, the depth changes presented suc h an importance that it would be possible to compare them reasonably w ith that it would be possible to compare them reasonably with the effe ct of the sowing date and year changes. In case of yields, the effect of depth changes was generally 2.5 times lower than that of sowing dat e and almost 5 times lower than that of growing year change. 10 mm-cha nge of sowing depth caused the variation change of yield amount on an average almost 0.4 per ha. The mentioned variability was then modified significantly not only by the corn hybrids of three different FAG-gro ups but by a size and shape of their seeds as well. The variability of the values of mentioned traits was evaluated by means of modified sta bility index (Mazur, 1992). Its primary modification for an odd number n of values X gives only the approximate results on the level of qual ity of variability. For this reason, an exact form of the modification concerning mainly the component A of the calculation of index was use d here (Fig. 1, 2, Tab. I).