The interaction effect of sodium chloride and chromium on some physiological characteristics of purslane (Portulaca oleracea L.)

The aim of this study was to investigate interaction of sodium chloride with chromium on vegetative, and physiological traits, uptake, and accumulation of sodium and chromium in roots and shoots of portulaca oleracea. In a completely randomized design with 3 replications, 4 salinity levels (0, 4, 8, 12 dsm-1‌) using sodium chloride every 4 days through irrigation water and five levels of chromium (0, 7, 14, 21, 28 mgkg-1 of dry soil weight) were applied in a pot experiment. Different levels of chromium treatment were prepared before sowing the seeds by adding potassium dichromate to the soil. The amounts of root chromium and shoots were measured by the atomic absorption spectrometry. Sodium contents of roots and shoots, root and stem length, root diameter and surface, greenness index, transfer factor, and bioaccumulation were measured after 60 days of cultivation. Results showed that an increase in different salinity level was associated with a significant increase in sodium and chromium content of roots, shoots and bioaccumulation factor. The highest amount of chromium, sodium, and bioaccumulation factor were observed at salinity levels of 12 dsm-1‌ and 28 mgkg-1. The interaction between salinity and chromium was significant. With an increase in the salinity level, the amount of plant root transfer factor showed an increasing trend and with increasing chromium, the transfer factor decreased. Root length, diameter, and surface as well as stem length and greenery index showed a significant decrease in plants treated with chromium and salinity. The combined effect of high levels of chromium and salinity led to a further reduction in the concentration and accumulation of minerals compared to each stress alone. Although salinity and chromium reduced the growth of portulaca oleracea, it seems that accumulation of significant amounts of sodium and chromium in the roots, prevents their excessive transfer to the shoots and further reduction in plant growth.