Effects of drought stress and soil compaction on some agronomic traits of maize (Zea mays L.)

In order to study the effect of drought stress and soil compaction on corn growth an experiment was carried out in 2012 at Safi Abad Agricultural Research Center. The treatments were arranged in split plot in a randomized complete block design with three replications on 704 single cross hybrid corn. Drought stress was considered as the main plot at 4 levels (irrigation after 75, 95, 115 and 135 mm evaporation from A pan), and soil compaction was as the subplot at 4 levels (no traffic congestion, mild with four times, the average density with 8 times and the intensity density with 12 times of tractor traffic). Based on the results, the drought and soil compaction stresses affected many of the traits. The effects of drought and soil compaction were statistically significant on stem diameter, root deep, number of brace roots per plant, root and shoot dry weight, harvest index, number of ear bearing plants at harvest and grain yield characteristics. The effect of soil compaction stress was significant on root dry weight and reduced it. Only the effect of drought stress was significant on chlorophyll and protein characteristics. Brace roots growth in soil compaction stress conditions was stimulated and was higher than drought conditions. But grain yield was not affected by increasing the number of brace roots. Increase in soil compaction prevented root growth to depth. Conversely, the drought stress cause increased root growth to depth. Stresses weakened maize stem diameter with constant process. The constant processes were observed in reduction of shoot and grain yield dry weight by application of stresses. The drought stress more than soil compaction can affect chlorophyll and protein content of grain. This indicates the important role of water in the field. Drought stress was able to reduce the harvest index, but soil compaction in the most severe condition can reduce it. Both stresses reduced the number of ear bearing plants.