Drought Effects on Yield and Yield Components in Different Growing Periods of Some Bread Wheat (Triticum aestivum L.) Genotypes

Drought is the mainly abiotic stress factor effect yield and quality. The research carried out in the experimental field of Trakya Agriculture Research Institute in 2008-2009 and 2009-2010 growing years. The research was set up with 15 genotypes in randomized completely blocks design in split plot with three replications. Drought treatments are placed on main parcel and genotypes on the sup-plot. Drought treatments were applied at various plant growth stages from shooting up to physiological maturating stage. Grain yield, biological yield, harvest index, number of spike per square meter, spikelet number per spike, number of grain per spike and length of spike and pairwise comparison were investigated among those characters. Drought stress had various impact on yield and yield component and there was various decreasing in grain yield in all genotypes depending upon drought stress application. Highest grain yield was obtained in Bereket cultivar with 658.3 kg da(-1). According to treatment the highest grain yield was determined with 763.8 kg da(-1) in non-stress condition. Under fully drought stress condition grain yield decreasing was 40.1%, under shooting stage of drought 28.0%, and during grain filling period of drought 26.2%. Drought stress on shooting stage more affected to grain yield than grain filling period. It was found positive and significant correlation between grain yields with biological yield, number of pike per square meter, number of grain per spike depending on drought stress increasing. Fully drought stress condition had significantly effect on biological yield and yield component followed by drought under shooting stage.