Effect of Different Media Cultures on Physico-Chemical Characteristics of Pot Marigold (Calendula officinalis L.) Plants under Salt Stress

Salinity is an important environmental tension limiting growth and productivity of plants worldwide. The harmful effects of high salinity on plants can be observed in senescence, necrosis of plant organs and decrease productivity. Major processes such as photosynthesis, protein synthesis, and energy and lipid metabolism affect plants during the beginning and development of salinity stress. Calendula officinalis L. belongs to the Asteraceae family; it is an annual with bright or yellow orange daisy-like flowers which are used for medicinal or culinary purposes. Organic fertilizers develop favorable physical, chemical and biological environment in the soil. They stimulate plant root growth, increase nutrient uptake and soil water-holding capacity, decrease evaporation from the soil and surface water runoff, facilitate drainage, regulate soil temperature and provide a rich substrate for soil microbes. This study was conducted to determine the effects of soil salinity and organic amendments on some growth characteristics, absorption of nitrogen, phosphorus and potassium and peroxidase enzyme activity in pot marigold plant (Calendula officinalis L). In a factorial experiment and completely randomized design (CRD), five levels of organic amendments (control, 0.5 and 1 g.L-1 algae extract, 20% v/v of pot volume cow manure and 20% v/v of pot volume vermicompost) and three levels of salinity (3.5, 7.5 and 10.5 dS.m-1) with three replications per treatments were applied. In this experiment, media without organic amendment were considered as control. Results showed that increasing soil salinity levels progressively decreased the growth characteristics and nutrients uptake. The maximum leaf number, fresh and dry weight of flowers and nitrogen, phosphorus and potassium absorption were obtained in cow manure treatment and EC = 3.5 dS.m-1, While the highest flower diameter was observed in sea algae treated plants (0.5 g.l-1) in media with EC = 7.5 dS.m-1. Salinity causes growth reduction due to the low osmotic potential of the medium and by a specific ion effect as a secondary cause in several vegetable crops. The results of the present study showed that the organic media can improve leaf number, crown diameter and fresh and dry weight of flowers. This can be due to increased media moisture storage and enhanced nutrient absorption. All treatments significantly increased growth characteristics of pot marigold compared to control. The positive effect of cow manure to nutrients uptake could be because of rich N, P, K compared to the others. According to the results, in normal conditions, pot marigold plant could tolerate salt stress until 7.5 dS.m-1 but by suitable media culture its threshold tolerate will be increased up to 10.5 dS.m-1. Also it was revealed that cow manure compared to other treatments could increase plant tolerate to salt stress and growth characteristics.