چكيده لاتين :
The objective ofthis field experiment was to evaluate the effect of humic acid application (2.5 kg ha-1 per plot) on yield components of 18F3 wheat hybrids (Triticum spp.) at four sowing times (St1, St2, St3 and St4) on clay soils of Central Anatolian field conditions in a randomized complete block design with four replications in 1999 and 2001. Genotypes were evaluated for plant height (PH-cm), spike number (SN-no), spikelet number (NSL-no), grain number (GN-no) and 1000-Grain weight (TKW-g). Humic acid (HA) decreased in all yield components in the St2, St3 and St4 dramatically by more than 33.0,75.0 and 45.0%, respectively. It was observed that separation among the genotypes on the basis of mean values was better under normal than under in any
stress factor in this region. Comparison of mean performance under these conditions revealed that the grain number, plant height and spike number were the most sensitive traits followed by rest of them. But, mentioned yield components not always sufficient. They must be supported any kind of soil conditioners such as HA in such regions. Moreover, correlation coefficients findings are being verified that sowing times are crucial importance (esp. first time) and it is being indicated that the most important trait was GN and TKW on the basis of their relationships with other traits. To be able to get higher wheat grain yield under Central Anatolian conditions, all sowing procedures must be done in time, different and soil conditioners (example HA) must be
used and proper agronomical precautions must be taken in time and adequately.
