Determination of drought tolerance level of maize (Zea mays L.) inbred lines and molecular characterization

The objective of the thesis were to test maize inbred lines for drought tolerance and determine the genetic distance of the inbreds by molecular markers.In the study twenty dent and flint temperate maize inbred lines were evaluated in well-watered and drought stress conditions in 2012 and 2013. Experiments conducted according to Randomized Complete Block Design with three replications. Soil moisture content of the experiment was determined by using a gravimetric method. Drought stress was achived at the flowering by withdrawn water approximately 2-3 weeks before flowering. Morphological, physiological and agricultural data were taken and genetic similarity of the lines were determined.The result of the study showed that, TK 72 (607.5 kg/da), TK 56 (538 kg/da), Ant-24702 (488 kg/da), Ant I-42 (456 kg/da), Ant-24698 (441.2 kg/da) and TK 12 (431.6 kg/da) were promising inbred lines in well-watered conditions. Ant I-69 (229.4 kg/da), TK 72 (220.5 kg/da), Ant-24702 (196.4 kg/da), Ant I-39 (174.6 kg/da) and Ant I-09 (146.8 kg/da) were determined as the most tolerant lines to drought, while Ant 910255 (27.6 kg/da), Ant I-46 (28.2 kg/da), Ant I-82 (29.0 kg/da) and Ant I-08 ( 45 kg/da) inbreds were identified as the sensitive lines in terms of yield . Tolerant promising lines Ant I- 69, TK 72, Ant-24702 , Ant I-39 and Ant I-09 were also had good performance in terms of secondary traits such as anthesis silking interval, number of ears per plant, number of kernel per cob, senescence, leaf rollinge, stomatal conductance, leaf chlorophyll content, water use efficiency, yield reduction ratio, drought resistance index and stress tolerance index.A wide genetic variation was detected with the molecular characterization of the lines. Unweighted pair group method with arithmetic mean dendogram revealed four main and eight sub-clusters. It was understood that the inbreds were belong to Lancaster, Stiff- Stalk, Tropical and unrelated genetic backround. The most promising tolerant inbred line, Ant I-69 formed an unknown single cluster. Also the lines representing Lancester heterotic group showed better performance than other groups. In conclusion, it was envisaged that temperate maize germplasm can be assessed for breeding drought tolerance and selected maize inbred lines were proposed for future studies.