III. International Agricultural, Biological & Life Science Conference, Edirne, Turkey, 1 - 03 September 2021, pp.259
Plants are often exposed to severe water regimes, i.e. flooding or drought, because of global climate change worldwide. These water extremes limit crop production as well as plant growth and development. The present study was carried out to assess the drought tolerance capacity of 15 soybeans (Glycine max L.) cultivars at the early seedling stage using the growth behaviours, water status (relative water content, RWC) and photosynthetic efficiency [performance index (PIABS)]. The seedlings of soybean were exposed to polyethylene glycol (PEG 6000) mediated drought stress [PEG was added to full strength Hoagland solution to obtain solutions of control (no PEG), -0.1, -0.3, -0.6 and -1.2 MPa] for 5 days, following 5 days of germination in the growth chamber at 25 ± 1 °C, 200 μmol m−2 s−1 light intensity, 8/16 hrs dark/light photoperiod, and 40 ±5% humidity. Photosynthetic performances of soybean cultivars which was measured by chlorophyll a fluorescence kinetics, were generally decreased in all cultivars with increasing drought stress levels. Besides, the length and fresh biomass of seedlings were significantly decreased with increasing drought, whereas dry biomass of cultivars was decreased in only Ataem, Cinsoy, Lider and SA-88 at elevated PEG levels. The RWC of tissues (cotyledon, hypocotyl and root) was significantly decreased with the increase of PEG level, and the highest decline in RWC was determined in the roots. In addition to that, the stress factor indexes (SFI) was calculated for all parameters measured in the study. According to total SFI values, soybean cultivars may be grouped as drought tolerant (Umut 2002, Mersoy, Lider, Soy Anam, SA 88), moderately tolerant (ANP-2018, Cinsoy, Asya, Ataem-7, Pınar) and susceptible (Traksoy, Yeşilsoy, Yemsoy, Türksoy, Bravo).