effect of salinity (nacl) stress on germination and early seedling growth of three medicinal plant species

Background: Salinity stress negatively affects the growth and yield of plants. Due to the increasing demand for products derived from medicinal plants and with regard to the growing problems caused by salinity of arable lands, the use of salt-tolerant species can be a strategic approach to cope with this problem. The aim of the present study was to evaluate the effect of salinity stress on germination and seedling growth of three medicinal plant species. Methods: Seeds of three species of medicinal herbs including isabgol (Plantago ovata L.), zucchini (Cucurbita pepo L.) and clove (Caryophyllus aromaticus L.) were exposed to different concentrations (0, 10, 20, 30 and 40 dS·m-1) of sodium chloride (NaCl). Results: It was observed that, except for zucchini, germination was inhibited at higher salinity regimes. NaCl treatment caused a serious decrease in the early seedling growth by means of reduced root and shoot length at higher salinity levels. Regression analysis of studied indices over salinity levels revealed that the highest and lowest slopes of regression lines belonged to isabgol and zucchini, respectively indicating high tolerance of zucchini and also, high sensitivity of isabgol to the imposed salinity levels. Conclusions: Based on the findings, zucchini was able to germinate more than 90% at 40 dS·m-1 of NaCl. Therefore, zucchini is suggested to be cultivated in farmlands which are relatively faced with the problem of soil salinity while, it is recommend that isabgol and clove not to be planted in such soils.