Effect of salinity and silicon on some morphophysiologic characters of purslane (Portulaca oleracea L.)

Purslane (Portulaca oleracea L.) is an annual salt-tolerant species, which could be considered as vegetable, fodder or medicinal plant in saline conditions. Silicon is the second mineral element in the earth's crust after oxygen. Although its role is not so clear in plant nutrition, silicon has positive effects on plant's yield and resistance to biotic and abiotic stresses. In order to study the effects of salinity and silicon application on some morphophysiologic parameters of purslane (Portulaca oleracea L.), a greenhouse experiment was conducted at Ferdowsi University of Mashhad in a split-plot arrangement based on completely randomized block design with 3 replications during summer 2008. Four salinity levels of NaCl (0.6, 7, 14, 21dS/m) were in main plots and two silicon levels (application of one mMol sodium silicate and not application) allocated to the subplots. The results showed that salinity up to 14 dS/m did not impose any significant differences in fresh and dry weight of leaves and stem, number of leaves, branches, leaf area index, specific leaf area and height of main stem compared with control but at 21 dS/m salinity all the above mentioned parameters decreased significantly, while specific leaf weight increased with increasing salinity. Application of silicon had a positive effect on number of leaves per plant, leaf area index and height of main stem. The results indicated that purslane (Portulaca oleraceae L.) could sufficiently tolerate saline conditions and can be considered as a medicinal plant in saline soils and arid regions. Also silicon application may improve plant's yield and tolerance to environmental stresses.