2018 ASHS Annual Conference

In some parts of the world droughts are threatening the supply of fresh vegetable production and currently a major limiting factor in agricultural productivity especially in developing regions. Some prospective strategies for improving drought tolerance may become increasingly more effective if the complex mechanism in the plant could be understood. For this reason, we investigated the change of photosynthetic activity, leaf water content and electrolyte leakage of squash (Cucurbita pepo L. cv. Sakız) under different irrigation levels with three different bacteria strains (Bacillus megaterium TV-91C, Bacillus megaterium TV-6D, Bacillus subtilis RK-1900) and product of methylamine (MA). Four irrigations levels (Full-irrigation; 100%, irrigation with 85% of the full-irrigation (mild), irrigation with 70% of the full-irrigation and irrigation with 55% of the full-irrigation (severe)) were followed in field. The effects of the applications on photosynthesis (Pn), stomatal conductance (gs), transpiration rate (Tr), concentration of intercellular CO₂ (Ci), electrolyte leakage (EL) and leaf relative water content (LRWC) of squash under water stress were observed.

In full irrigation, the highest gs and Tr were obtained at RK1900+MA application, while the highest Pn and LRWC were recorded at of TV91C+MA application. All the measured parameters were improved by the application of used bacteria and MA application at different drought levels. Also LRWC were increased under different level of droughts as compared to control treatment. In the severe drought level, the highest Ci, Tr and LRWC were obtained at the RK1900+MA application, while the highest Pn were recorded at TV91C+MA application. We found that TV91C was the most effective bacteria on photosynthesis activity that caused 20% increase under full irrigation and 28% increase under severe drought conditions.