The Study of salinity (NaCl) stress on ontogeny of vegetative organs in Luffa cylindrica L

Luffa cylindrica L. (Cucurbitaceae family) is an herbal plant with high medicinal and economical usage. Due to the salinity problem in soils of the country, the effect of salinity stress on the development of vegetative organs of luffa was investigated. Seeds were planted in pots (control and 3 treatments with four replications) and treated with 15, 30 and 45 mM NaCl under drip irrigation two weeks before flowering. The root, stem, leaf and petiole of plants were fixed in Glyceraldehide fixator solution. The common methods of cell – histology was used for preparing of section. Vegetative meristem was removed in different stages, fixed in FAA70% and maintained in ethanol70%. The microtome was used for vegetative meristem sections and staining was carried out with PAS (Periodic Acid Schiff) and Hematoxyline. The results showed increasing salinity decreased the height, internode distance and overall size of plant. Increasing salt concentration causes the growth in the thickness of methaxylem elements at the root, leads the stem to go to subsequent structure earlier than normal process, have the cell layers increase in number, and increase the activity of the generative layers. In leaves, findings also showed that different salt concentration lead to increasing of ladder parenchyma layers, number and length of trichomes. Under the treatment meristem vegetative tip of the stem was layered. At the higher concentration vegetative tip became wide and got homogeneous pigment similar to what is seen in generative meristem. This phenomenon can be the sign of premature aging of the plant.