Evaluating Foliar Responses of Sunflower Genotypes under Drought Stress

As a summer crop, sunflower (Helianthus annuus L.) is influences commonly by drought stress due to growing generally in rain fed regions without irrigation. Drought affects severely not only seed yield both also other important yield traits which plays important roles on yield formation in sunflower. Therefore, drought resistance became one of the most important goals in the sunflower breeding programs in the world. The study was conducted to determine drought tolerance levels of sunflower genotypes under controlled environmental conditions in Edirne which is a border city in Trakya region which is European part of Turkey and has about 50% of Turkish sunflower production areas. Sunflower restores lines which developed in National Project were evaluated foliar responses against drought stress. Based on study results, the most affected foliar trait was leaf area and it was reduced until 75%. Similarly, leaf number of plants also influenced severely especially from earlier droughts and plants responded about 60% leaf number decreases. On the other hand, on the chlorophyll content of plant leaves, sunflower genotypes responded differently both in earlier (R.3) and later (R.5.1) plant growth stages. While chlorophyll content of sunflower lines increased about 40-50%, some of them decreased about 30%. Similarly, sunflower genotypes responded differently drought stress in their foliar traits depending on when stress applied early or late. As results, sunflower genotypes had different tolerance to drought and higher tolerant ones will be considered to develop tolerant hybrids and will be used as initial material for further breeding purposes.