Effect of drought stress on some physiological parameters of two potato cultivars (Kenebec and Concord) under in vitro culture condition

Drought as one of the environmental stresses, is the most significant factor restricting plant growth and crop production. Drought stress can results in disruption of water potential gradients, turgor loss, membrane integrity disruption and protein denaturation. In addition, it inhibits the photochemical activities. Potato is an important plant in agriculture that has an average sensitivity on salt and a high sensitivity on draught. In this study, potato’s residence against draught was investigated in two cultivars of Kenebeck and Concord under in vitro culture conditions. Potato cultivars were grown in MS medium containing 50 μM Silver Thiosulfate (STS) and they were transferred to liquid medium of MS after rooting then were treated for 14 days with concentration of 0, 2 and 4 percent of PEG (MW 6000). After four weeks post treatment, physiological factors such as fresh and dry weight, content of photosynthesis pigments (total chlorophyll and carotenoid) were measured in order to identify resistant and sensitive plants against water stress. Results indicated that Kenebec showed lower reduction in the above-mentioned factors under stress conditions compared to Concord. In order to study mechanisms of resistance against draught in these two types, proline and soluble carbohydrate in shoot were investigated. According to results, with increasing, PEG concentration proline and the soluble carbohydrate increase significantly in the shoots Kenebec. Proline concentration in Concord showed an increase only 2% PEG treatment. In comparison to control plants, soluble carbohydrates in Concord showed  no significant increase