Some germination characteristics of Portulaca oleracea L., Malva neglecta Wallr., and Amaranthus retroflexus L. under salinity and drought Stress conditions

One of the major problems in arid and semi-arid conditions is the lack of irrigation water, and soil and water salinity. In order to investigate the effect of salinity and drought stress on the quantitative and qualitative germination characteristics of portulaca, malva and amaranthus, a study done as factorial in a completely randomized design with three replications in the research laboratory of the Faculty of Agriculture in 2016. In the first experiment first factor was effect of salt stress including NaCl was the effect of osmotic potential level (0, -6 and -12 bar) and the Second factor three weeds spicefic (Portulaca, Malva and Amaranthus). In the second experiment first factor was effect of drought stress including PEG 6000 was the effect of osmotic potential level (0, -3 and -6 bar) and the Second factor three weeds spicefic (Portulaca, Malva and Amaranthus). The results showed that all the studied traits except the germination percentage in cheese plant were affected by the interaction effects of salinity and drought stress. Salinity and drought stress reduced most of the studied traits in each plant. In non-stress conditions, portulaca and amaranthus had the highest percentage of germination and seedling germination vigor, however, increasing the activity of catalase, peroxidase and protein concentrations in cheese plant, especially in salinity stress -6 times and drought-3 times, indicated a higher resistance of this plant than the other two species. In the case of portulaca and amaranthus, salinity and drought stress reduced seed germination, which seems to reduce germination due to reduced water availability or interference with some aspects of metabolism, such as altering the balance of growth regulators.