Impaginato 345 Adv. Hort. Sci., 2019 33(3): 345-358 DOI: 10.13128/ahs-23714 Effect of vermicompost on morphologi- cal and physiological performances of pot marigold (Calendula officinalis L.) under salinity conditions N. Adamipour 1 (*), M. Khosh-Khui 1, H. Salehi 1, H. Rho 2 1 Department of Horticulture Science, School of Agriculture, University of Shiraz, Iran. 2 Plant Stress Laboratory Texas, A&M AgriLife Research at Amarillo, 6500 Amarillo Blvd., West Amarillo, TX 79106‐1796, USA. Key words: antioxidative enzymes, chlorophyll content, fertilizer, nutrient ele- ments. Abstract: A greenhouse study was conducted in order to evaluate the interac- tions of vermicompost and salinity effects on morphology and physiology of pot marigold. The experiment was conducted with vermicompost treatments at five levels (0%, 5%, 10%, 15% and 20%) and salinity treatments at five levels (0, 50, 100, 150 and 200 mM NaCl) in a completely randomized factorial design arrangement with four replications. Results showed that increasing levels of salinity led to decline in leaf area, fresh and dry weights of flower, shoot, and root, N, P, K, Fe, Mg and Zn concentrations, chlorophyll and carotenoid con- tents, while proline content increased in the plants. APX, SOD, POD and CTA enzyme activities significantly increased with increasing salinity from 0 to 150 mM NaCl, then declined in 200 mM treatment in the plants. Application of ver- micompost increased the morpho-physiological indices and mineral nutrient uptake in the plants and could increase the plant yield by alleviating the harm- ful effects of salinity. 1. Introduction Calendula officinalis, known as “pot marigold”, is a plant in Calendula genus of Asteraceae family. It is perhaps native and widely naturalized further Northern to Southern Europe and elsewhere in warm temperate regions of the world, and it may possibly be planted widely in gardens and landscapes (Gharineh et al., 2013). Among ornamental bedding plants, pot marigold is known to grow well under saline conditions. In fact, some pot marigold cultivars that are used as cut flowers or as bed- ding plants in landscaping can be grown by maintaining the quality of plants under saline conditions with an ECw of <8 dS m -1 (Koksal et al., 2016). Plants are exposed to ever-changing and often unfavorable environ- mental conditions, which cause both biotic and abiotic stresses such as extreme temperatures, flood, drought, and salinity. Overexploitation of (*) Corresponding author: nader.adamipour@shirazu.ac.ir Citation: ADAMIPOUR N., KHOSH-KHUI M., SALEHI H., RHO H., 2019 - Effect of vermicompost on morphologi‐ cal and physiological performances of pot mari‐ gold (Calendula officinalis L.) under salinity condi‐ tions. - Adv. Hort. Sci., 33(3): 345-358 Copyright: © 2019 Adamipour N., Khosh-Khui M., Salehi H., Rho H. This is an open access, peer reviewed arti- cle published by Firenze University Press (http://www.fupress.net/index.php/ahs/) and distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Data Availability Statement: All relevant data are within the paper and its Supporting Information files. Competing Interests: The authors declare no competing interests. Received for publication 18 July 2018 Accepted for publication 23 April 2019 AHS Advances in Horticultural Science http://creativecommons.org/licenses/by/4.0/ http://creativecommons.org/licenses/by/4.0/ http://creativecommons.org/licenses/by/4.0/ Adv. Hort. Sci., 2019 33(3): 345-358 346 available water resources as well as environmental factors such as low precipitations, high temperatures and contamination from parental rocks are leading to increases in soil salinization (Aroca et al., 2013). Soil salinization is one of the most important agricultural and eco-environmental problems nowadays, which is increasing steadily in many parts of the world. Saline soils have been estimated to occupy more than 7% of the Earth’s land surface and it is expected to be increased by up to 50% by the middle of the twenty- first century (Ruiz-Lozano et al., 2012). Salinity stress is one of the major abiotic threats to plant life and agri- culture worldwide and significantly reduces crop yield in the affected areas. Excessive salt above what plants need limits plant growth and productivity and can lead to plant death. About 20% of all irrigated land is affect- ed by soil salinity, decreasing crop yields. Plants are affected by salinity stress in two main ways: osmotic stress and ionic toxicity. These stresses affect all major plant processes, including photosynthesis, cellular metabolism, and plant nutrition (Aslamsup et al., 2011). Amelioration of salt-affected soils can be accomplished through many effective methods, such as water leaching, chemical remediation, and phytore- mediation (Qadir et al., 2007). The amelioration of salt-affected soils using chemical agents, including gyp- sum, calcite, calcium chloride and organic matter, is a successful approach that has been implemented worldwide (Sharma and Minhas, 2005; Tejada et al., 2006). According to a study, the application of organic matter conditioners has become a common practice in salt-affected areas in the last several decades and con- stitutes an important method of soil regeneration and fertility enhancement (Melero et al., 2007). Organic matter is very important for maintaining structural sta- bility in soils as well as improving the physical, chemi- cal and biological properties of soils. Salt-affected soils generally exhibit poor structural stability due to low organic matter. The addition of organic materials (e.g. green, farmyard and poultry manures, compost, food processing wastes, etc.) has been suggested for improving structural stability of soils by many researchers (Tejada et al., 2006). Barzegar et al. (1997) found that addition of plant residues improved the water-stable aggregate in soils because of increased organic matter content and decreased soil salinity. The application of organic matter for soil remediation is considered essential for sustainable land use and crop productivity. Given the importance of pot marigold in green space, and their being placed in saline soils in most cultivable regions, so far, enough research has not been conducted to understand morpho-physiolog- ical properties of pot marigold under salinity stress conditions and determine the status of vermicompost in reducing the devastating effects of salinity stress in pot marigold. For this purpose, an experiment was conducted to determine the effects of vermicompost on some morphological and physiological characteris- tics of pot marigold under salinity stress conditions. 2. Materials and Methods To investigate the effects of vermicompost on some physiological characteristics of pot marigold (Calendula officinalis L. cv. Candyman Orange) under salinity stress, a greenhouse experiment was con- ducted in a completely randomized factorial design including vermicompost at five levels (0%, 5%, 10%, 15% and 20%) and salinity stress at five levels (includ- ing 0, 50, 100, 150 and 200 mM NaCl) with four repli- cates. This study was conducted at the Research Greenhouse of the Department of Horticultural Science, College of Agriculture, Shiraz University, Shiraz, Iran (52°32´E and 29°36´N). After disinfection of pots (20 and 30 cm in diameter and length, respec- tively), 5%, 10%, 15% and 20% (v/v) vermicompost from Kian Pars Shiraz Company, were dried in the shade and were mixed with four kilograms of a native soil. The main physical and chemical characteristics of the vermicompost and soil mixture are shown in Table 1. Then, four marigold seeds were planted in each pot. The pots containing seeds were kept in a greenhouse with 27/18°C (day/night) temperature, 16 h light conditions, and 35% relative humidity. After germination of seeds one plant was selected in each pot and the three other plants were removed. When the plants reached the four-leaf stage, the plants were treated with four levels of salinity stress. Table 1 - Some physico-chemical properties of vermicompost and soil Sample Vermicompost Soil Organic matter % 33 0.41 pH 8.1 7.05 EC (d/Sm) 1.7 0.6 P (%) 1.8 PWP (%) 5.1 K (%) 1.2 FC (%) 14 C/N 13 Total N (%) 1.5 Soil texture Sandy-loam Adamipour et al. ‐ Effect of vermicompost on performances of pot marigold 347 Salinity stress treatment was applied by adding net quantities of sodium chloride (NaCl) to the irrigation water so that pots were irrigated with 50, 100, 150, and 200 mM NaCl containing water based on field capacity of the soil, and the amount of the decreased water obtaining by the salinity treatment resulted in the average electrical conductivity (EC) of 3.62, 6.27, 9.36 and 12.71 dS/m in each level of the treatment, respectively. The control treatment was applied using distilled water. After 35 days of the treatments, the plants were harvested in order to measure morpho- logical and biochemical traits. Growth parameters Growth parameters including, flower diameter (mm), leaf area (cm2) and fresh and dry weights of flower, shoot, and root (g) were measured. For dry weight determination, the shoots, roots, and flowers were dried in an oven at 70°C for 48 h and weighed. Proline content The leaf proline content was determined using the method of Bates et al. (1973). Proline was extracted from leaf samples of 100 mg weight fresh with 2 ml of 40% methanol. 1 ml of the extract was mixed with 1 ml of a mixture of glacial acetic acid and orthophosphoric acid (6 M) (3:2, v/v) and 25 mg nin- hydrin. After 1 h of incubation at 100°C, the tubes were cooled, and 5 ml toluene was added. The absorbance of the upper phase was spectrophoto- metrically determined at 528 nm. The proline con- centration was determined using a standard curve. Chlorophyll and carotenoid contents Chlorophyll and carotenoid contents were esti- mated by the method of Hiscox and Israelstam (1979). Fresh leaf and petal material (1 mg) and 10 ml DMSO were taken in vials and kept in an oven at 65°C for 4 h. Absorbance was read at wavelengths of 665 and 649 for leaves, and 480 nm for petals using a spectrophotometer (Beckman DU 640 B, Fullerton, USA). The following equations were used to calculate each compound. Chl a= (12.47×A665)-(3.62×A649) Chl b= (25.06×A649)-(6.5×A665) Total chlorophyll (mg g-1 F.W.) = Chla + Chlb Carotenoids (mg g-1 F.W.) = where A stands for the absorbance reading of a sam- ple at 665, 649 and 480 nm of wavelength. Antioxidant analysis Fresh leaf samples were homogenized in extrac- tion buffer (0.1 M phosphate buffer pH 6.8) with a mortar and pestle on ice. The homogenate was then centrifuged at 12,000 g for 15 min at 4°C and the supernatant was used as the crude extract for the superoxide dismutase, guaiacol peroxidase, ascor- bate peroxidase and catalase. The superoxide dismu- tase (SOD), guaiacol peroxidase (POD), ascorbate per- oxidase (APX) and catalase (CAT) enzymes were esti- mated using the methods previously described by B e a u c h a m p a n d F r i d o v i c h ( 1 9 7 1 ) , C h a n c e a n d Maehly (1955), Nakano and Asada (1981), and Dhindsa et al. (1981), respectively. Plant nutrient element analysis Leaf material was ground to pass 0.5 mm sieve in a cyclone laboratory mill, weighed into ceramic cru- cibles, ashed overnight at 550°C in a muffle furnace, and the ash was suspended in 2M HCl for determina- tion of mineral nutrients. Then, total nitrogen (N), phosphorus (P) and potassium (K) were determined in the leaf using the Kjeldahal, colorimetrically and ammonium acetate methods respectively., Zinc (Zn), magnesium (Mg) and Iron (Fe) were determined by atomic absorption spectroscopy (Baumard et al., 1998). Statistical analyses The data were analyzed using one-way analysis of variance at P < 0.05 significance with SAS version 9.4 software (SAS Institute Inc., Cary, NC). Fisher’s LSD test was conducted to determine the statistical dif- ferences among different treatments. 3. Results and Discussion Leaf area and fresh and dry weight of shoots The growth (leaf area and fresh and dry weight of shoots) was significantly affected by the treatments (Table 2). The treatment of plants with NaCl signifi- cantly reduced the growth parameters and the decrease was proportional to the concentration of NaCl. The highest concentration (200 mM NaCl) was the most deleterious and decreased the leaf area by 53.32%, fresh weight by 72.76%, and dry weight by 48.74% as compared to those of the control plants. However, all the above parameters were significantly enhanced by the vermicompost treatments. The highest and the lowest leaf area and fresh and dry weight of shoots were obtained in the 20% vermi- compost and the control treatment, respectively (Table 2). Leaf area and fresh and dry weight of shoots increased (12.03%, 39.52% and 38.96%, respectively) at the 20% vermicompost treatment compared to the control plants. Researches showed 1000 480 1 29 53 78 220      A Chla Chlb. . Adv. Hort. Sci., 2019 33(3): 345-358 348 that soil salinity reduces the growth of plant shoots. This water potential reduction in the soil or osmotic effect is due to the presence of salt in the soil which limits the root water absorption (Nguyen et al., 2015). In the salt stress, the plant’s hormonal system which synthesizes and transmits a number of hor- mones such as cytokinins is impaired and their trans- port from roots to the upper parts of the plant is lim- ited. The termination of the hormone transfer from roots to branches and the consequent reduced water absorption capacity can lead to a decline in plant growth. Reduction of leaf area can be explained by decreased cell growth or a reduced cell division rate due to decreased cellular turgor. Decrease in leaf area also reduces the rate of photosynthesis, result- ing in decreased fresh and dry weight of plants (Zarei et al., 2016). In addition, Alshammary et al. (2004) showed that decrease in growth was due to reduc- tion of flexibility, development of cells, and reduction of auxins. Vermicompost, due to its high microbial activity resulting from the presence of fungi, bacteria, yeasts, actinomycetes, and algae, can produce diffe- rent growth regulators such as auxins, gibberellins, and cytokinins all of which may have positive effects on plant growth and development (Xu et al., 2016; Ullah et al., 2018). Thus, the cause of rises in height and leaf area of the plants treated with vermicompo- st is probably from the stimulation of production of growth regulators including auxins and gibberellins. Furthermore, vermicompost contains humic substan- ces that increase the availability of plant N, P, K, and in particular Zn for the synthesis of tryptophan, a pre- cursor to auxins that are used for rooting and plant growth (Sharifianpour et al., 2015; Scaglia et al., 2016). Fresh and dry weight of roots The fresh and dry weight of roots of the pot marigold plants was lower with the salinity stress treatments as compared to that of the plants under non-saline conditions (Table 3). Fresh and dry weight of roots decreased (51.91% and 77.98%, respectively) Table 2 - Effect of salinity and vermicompost and their interaction on leaf area and shoot fresh and dry weight * In each variable, data followed by the same letters (small letters for interactions and capital letters for means) are not significantly dif- ferent using LSD at 5% level. Data represent the mean value ± S.D. the mean of four replicates. Vermicompost (%) Salinity (mM) Mean vermicompost 0 50 100 150 200 Leaf area 0 36.10±1.33 gh 36.10±0.62 gh 35.12±0.62 i 27.15±0.62 m 15.91±0.62 q 30.05±8.10 E 5 37.05±0.62 f 36.71±0.62 fg 35.01±0.62 gh 27.85±0.62 m 16.61±0.62 q 30.03±8.08 D 10 38.39±0.62 de 38.05±0.62 e 37.16±0.62 f 29.19±0.62 l 17.95±0.62 p 32.14±8.08 C 15 39.28±0.62 bc 38.94±0.62 cd 38.05±0.62 e 30.08±0.62 k 18.84±0.62 o 33.03±8.08 B 20 40.40±1.18 a 40.06±1.18 ab 39.17±1.18 cd 31.20±1.18 j 19.96±1.18 n 34.16±8.08 A Mean salinity 38.24±1.73 A 37.95±1.65 A 37.06±1.65 B 29.09±1.65 C 17.85±1.65 D Shoot fresh weight (g) 0 59.92±1.18 h 57.79±1.18 i 54.37±1.18 k 27.19±1.18 n 9.79±1.18 p 44.05±1.92 E 5 60.62±0.62 h 58.49±0.62 i 55.07±0.62 kj 39.11±0.62 m 10.49±0.62 p 44.75±1.92 D 10 70.35±0.82 e 68.22±0.82 f 64.22±0.82 f 48.84±0.82 l 20.22±0.82 o 54.49±1.92 C 15 76.27±0.91 ab 74.14±0.91 c 74.14±0.91 c 54.76±0.91 kj 26.14±0.91 n 60.41±1.92 B 20 77.32±0.75 a 75.19±0.75 bc 75.19±0.75 bc 55.8±0.751 j 16.22±0.75 n 61.46±1.92 A Mean salinity 68.89±7.67 A 66.76±7.67 B 63.34±7.67 C 47.38±7.67 D 18.76±7.67 E Shoot dry weight (g) 0 13.18±1.18 gh 12.84±1.18 hi 11.38±1.1 8 jk 8.92±1.18 mn 5.8±1.18 1p 10.42±3.01 E 5 13.88±0.62 fg 13.54±0.62 fgh 12.08±0.62 ij 9.62±0.62 lm 6.5±0.621 p 11.12±2.87 D 10 15.22±0.62 cd 14.88±0.62 de 13.42±0.62 gh 10.96±0.62 k 7.85±0.62 o 12.46±2.87 C 15 16.11±0.62 b 15.77±0.62 bc 14.31±0.62 ef 11.85±0.62 j 8.74±0.62 n 13.35±2.87 B 20 17.23±0.62 a 16.89±0.62 a 15.43±0.62 bcd 12.97±0.62 h 9.62±0.62 lm 14.48±2.87 A Mean salinity 15.12±1.65 A 14.78±1.65 A 13.32±1.65 B 10.86±1.65 C 7.75±1.6 5 D Adamipour et al. ‐ Effect of vermicompost on performances of pot marigold 349 vated the amount of biomass; the total fresh and dry weightwere 31.37% and 79.04% higher than those of the control plants, respectively. The vermicompost treatments also improved the amount of biomass in the plants that were subjected to the salinity stress treatments (Table 3). Edwards and Burrows (1988) reported that increase in fresh and dry weight of roots depends on increase in the activity of hormonal substances such as auxins, cytokinins, and gib- berellins as well as vitamin B12. Flower diameter and fresh and dry weight of flower Flower diameter and fresh and dry weight of flower of the pot marigold plants were found to sig- nificantly decrease as the salt concentration was raised. These parameters decreased (33.58%, 67.94% and 27.48%, respectively) at the salinity level with 200 mM NaCl compared to the control treatment (Table 3 and 4). Several reports have shown that salinity decreases the flower diameter and fresh and dry weight of flower in (Zinnia elegans) (Carter and Grieve, 2010), Madagascar periwinkle (Cathasanthus r o s e u s ) ( J a l e e l e t a l . , 2 0 0 8 ) a n d g a r d e n m u m (Chrysanthemum× morifolium) (Lee and Van Iersel, 2008). The vermicompost applications significantly at salinity level of 200 mM NaCl compared to the control treatment. Ionic toxicity, nutritional imbal- ance, and osmotic osmolality adjustment are the negative effects of salinity stress on plant metabo- lism. Roots are the organ responsible for absorbing water and minerals, and salinity stress affects plant shoots more than the root system; however, the root system is the first organ that is exposed to salinity stress (Demiral and Türkan, 2005). One of the most effective indices in salinity tolerance is the mainte- nance of cellular turgor and osmotic regulation due to salt absorption and organic matter production. Plants, for production of organic materials such as glycine betaine, sorbitol, mannitol, and proline, spend a large amount of energy to regulate osmotic resistance in response to salinity stress. As a conse- quence, plants under salinity stress conditions reduce root efficacy in supplying nutrients and water to other organs. This reduces growth of shoots and dry matter production, and eventually reduces the trans- fer of nutrients from roots to shoots, and thus leads to a reduction in dry weight of roots and stems of plants (Claussen, 2005; Butt et al., 2016; Sattar et al., 2016). The vermicompost treatments of the plants grown under stress-free conditions significantly ele- Table 3 - Effect of salinity and vermicompost and their interaction on root fresh and dry weight and flower diameter * In each variable, data followed by the same letters (small letters for interactions and capital letters for means) are not significantly dif- ferent using LSD at 5%level. Data represent the mean value ± S.D. the mean of four replicates. Vermicompost (%) Salinity (mM) Mean vermicompost 0 50 100 150 200 Root fresh weight (g) 0 13.33±0.54 bcd 13.25±0.54 bcd 13.18±0.54 cde 9.28±0.54 fg 6.26±0.54 i 11.06±2.96 D 5 13.33±1.32 bcd 13.46±1.32 bcd 12.08±1.32 ij 9.49±1.32 fg 6.30±1.32 i 11.24±3.18 D 10 14.46±0.73 b 14.38±0.73 bc 14.31±0.73 bc 10.41±0.73 f 6.47±0.73 i 12.00±3.34 C 15 16.01±1.24 a 15.93±1.24 a 15.86±1.24 a 11.96±1.24 e 7.85±1.24 h 13.52±3.48 B 20 17.02±0.66 a 16.94±0.66 a 16.87±0.66 a 12.97±0.66 de 8.86±0.66 gh 14.53±3.36 A Mean salinity 14.87±1.69 A 14.79±1.69 A 14.72±1.69 A 10.82±1.69 B 7.15±1.36 C Root dry weight (g) 0 6.50±0.54 d-g 6.38±0.54 efg 6.07±0.54 fg 2.17±0.54 jk 0.83±0.54 l 4.39±2.51 D 5 6.71±1.32 e-g 6.59±1.32 e-g 6.28±1.32 fg 2.38±1.32 ijk 0.89±1.32 l 4.57±2.73 D 10 7.63±0.73 cd 7.51±0.73 de 7.20±0.73 def 3.30±0.73 ij 1.30±0.73 ik 5.38±2.76 C 15 9.18±1.24 ab 9.06±1.24 ab 8.75±1.24 bc 4.85±1.24 h 3.43±1.24 i 6.85±3.02 B 20 10.19±0.66 a 10.07±0.66 a 9.76±0.66 ab 5.86±0.66 gh 7.85±0.66 h 7.86±2.87 A Mean salinity 8.04±1.69 A 7.92±1.69 A 7.61±1.69 A 3.71±1.69 B 1.77±1.28 C Flower diameter (mm) 0 65.50±1.91 cde 61.50±1.91 def 59.50±1.91 fg 52.50±1.91 i 41.50±1.91 k 55.50±8.20 C 5 62.50±2.08 cde 61.50±2.08 def 59.50±2.08 fg 52.50±2.08 i 41.50±2.08 k 55.50±8.23 C 10 63.25±2.98 bcd 62.25±2.98 c-f 60.25±2.98 ef 53.25±2.98 i 42.25±2.98 k 56.25±8.45 C 15 65.00±3.55 abc 64.00±3.55 bcd 62.00±3.55 def 55.00±3.55 hi 44.00±3.55 kj 58.00±8.62 B 20 67.00±1.41 a 66.00±1.41 ab 64.00±1.41 bcd 57.00±1.41 gh 46.75±1.41 j 60.15±7.85 A Mean salinity 65.05±2.85 A 63.05±2.85 A 61.05±2.85 B 54.05±2.85 C 43.20±3.03 D 350 Adv. Hort. Sci., 2019 33(3): 345-358 increased these parameters compared to the control under both absence and presence of the salinity stress treatments. The 20% vermicompost treatment under salinity stress conditions gave the higher val- ues for these parameters than those with the other t r e a t m e n t s ( T a b l e 3 a n d 4 ) . T h e e x t e n t o f t h e increase in the values mentioned above was by 8.37%, 56.53% and 6.19 in the 20% vermicompost treatment as compared with those of the control, respectively. Hidalgo et al. (2006) stated that using vermicompost fertilizer increased flower diameter and fresh and dry weight of flower in marigold which is consistent with the findings of this study. Proline content As shown in Table 4, proline content of the pot marigold plants was markedly increased by the salini- ty stress treatments. The maximum and the mini- mum proline content were observed in the 200 mM NaCl and the control treatments, respectively. Proline content increased 447.87% at 200 mM NaCl compared to the control treatment (Table 4). Proline content increase is one of the protective mechanisms of this plant against salinity stress. It has been repor- ted when plants are exposed to salinity stress, the breakdown of proteins and thus the increase of amino acids and amides accelerates, one of which is proline (Iqbal et al., 2015). Protein degradation, decrease in proline oxidase enzyme activity, and exacerbation of P5CS gene expression are the most important factors affecting proline concentration under stress conditions. Increase in P5CS gene expression is one of the most important factors affecting proline concentration under stress condi- tions (Kubala et al., 2015). The proline content was clearly affected by the vermicompost treatments. As compared to the control, the increase was 1.28% at 20% vermicompost. Interaction between levels of salinity and vermicompost resulted in the highest and the lowest proline content in the plants with 200 mM NaCl and 20% vermicompost treatment and with 0 mM NaCl and 0% vermicompost treatment, respec- tively (Table 4). In this study, the application of ver- micompost increased proline content and reduced the damaging effects of salinity stress. Vermicompost increases the amount of N available in plants due to the presence of N in the proline structure, which leads to increased proline synthesis under salinity conditions and increased plant resistance to salinity stress (Rafiee et al., 2017). Table 4 - Effect of salinity and vermicompost and their interaction on flower fresh and dry weight and proline content * In each variable, data followed by the same letters (small letters for interactions and capital letters for means) are not significantly dif- ferent using LSD at 5%level. Data represent the mean value ± S.D. the mean of four replicates. Vermicompost (%) Salinity (mM) Mean vermicompost 0 50 100 150 200 Flower fresh weight (g) 0 4.35±0.57 ef 4.28±0.57 ef 3.88±0.57 fg 2.89±0.57 ij 1.04±0.57 m 3.29±1.37 D 5 4.71±0.65 de 4.64±0.65 de 4.24±0.65 ef 3.25±0.65 ih 1.56±0.65 lm 3.68±1.33 C 10 5.07±0.65 d 5.00±0.65 d 4.60±0.65 de 2.37±0.65 jk 1.92±0.65 kl 3.79±1.51 C 15 6.25±0.47 bc 6.18±0.47 bc 5.78±0.47 c 3.55±0.47 gh 2.03±0.47 kl 4.76±1.77 B 20 6.93±0.82 a 6.86±0.82 a 6.46±0.82 ab 3.27±0.82 ih 2.22±0.82 kl 5.15±2.16 A Mean salinity 5.46±1.14 A 5.39±1.14 A 4.99±1.14 B 3.07±0.74 C 1.75±0.65 D Flower dry weight (g) 0 1.26±0.07 e-h 1.25±0.07 e-h 1.20±0.07 hi 1.11±0.07 jkl 0.84±0.07 p 1.13±0.07 C 5 1.27±0.06 e-g 1.26±0.06 e-g 1.21±0.06 gh 1.12±0.06 jk 1.05±0.06 lm 1.16±0.07 B 10 1.30±0.05 cde 1. 30±0.05 cde 1.23f±0.05 gh 1.14±0.05 ji 0.88±0.05 op 1.18±0.07 AB 15 1.30±0.01 cde 1.30±0.01 cde 1.28±0.01 e-g 1.07±0.01 klm 1.04±0.01 m 1.20±0.08 A 20 1.40±0.05 a 1.38±0.05 ab 1.36±0.05 bcd 0.96±0.05 n 0.92±0.05 no 1.20±0.09 A Mean salinity 1.31±0.22 A 1.29±0.13 A 1.25±0.16 B 1.08±0.10 C 0.95±0.16 D Proline content (µmol g‐1 F.W.) 0 4.19±0.12 k 4.31h±0.12 ij 4.76±0.12 f 10.32±0.12 d 23.18±0.12 b 9.35±7.47 D 5 4.20±0.11 k 4.32±0.11 hi 4.77±0.11 f 10.33±0.11 d 23.19±0.11 b 9.36±7.47 D 10 4.22±0.10 k 4.35±0.10 h 4.80±0.10 f 10.35±0.10 d 23.22±0.10 b 9.39±7.47 C 15 4.28±0.08 j 2.40±0.08 g 4.85±0.08 e 10.41±0.08 c 23.27±0.08 a 9.44±7.47 B 20 4.30±0.07 ij 4.42±0.07 g 4.87±0.07 e 10.43±0.07 c 23.30±0.07 a 9.47±7.47 A Mean salinity 4.24±0.10 E 4.36±0.10 D 4.81±0.10 C 10.37±0.10 B 23.23±0.10 A Adamipour et al. ‐ Effect of vermicompost on performances of pot marigold 351 Chlorophyll content The plants treated with NaCl exhibited a signifi- cant decrease in chlorophyll content and the greatest damage was caused by 200 mM NaCl treatment. In comparison with the control, chlorophyll content decreased by 28.12% with 200 mM NaCl treatment (Table 5). Whereas, the vermicompost treatments reversed the adverse effects of NaCl and caused a significant increase in chlorophyll content in the salt- treated plants (Table 5). The highest value of chloro- phyll content in leaves (18.71%) was recorded in the vermicompost-treated plants over the control plants. Usually, decreasing chlorophyll when plants face stress conditions may be due to an alternation in N metabolisms in relation to the production of compo- sitional compounds such as proline, which are used in osmosis regulation, because an increase in proline production causes glutamate to less involve in the chlorophyll biosynthesis pathways (Jaleel et al., 2008; Håkanson and Eklund, 2010). In addition, increased oxidative stress that is caused by reactive oxygen species damage to the chloroplast structure reduces the concentration of chlorophyll. Reduction of chlorophyll content has been reported in plants under salinity stress conditions due to the activity of chlorophyllase enzyme. Furthermore, some growth regulating agents such as abscisic acids and ethylene stimulate the activity of this enzyme (Ali et al., 2004; Zhao et al., 2007). The application of vermicompost significantly increased chlorophyll content in the leaves in the present study. Vermicompost increases the synthesis of chlorophyll under salinity stress con- ditions by providing nutritious elements such as Fe, Zn, Mg, and N directly and indirectly (Nadi et al., 2011; Narkhede et al., 2011). Total carotenoid content The content of carotenoid decreased in the plants that received 50, 100, 150 and 200 mM NaCl concen- trations. The content of carotenoid was the lowest (37.16% over control) for the plants that received the highest level of the salinity treatment (200 mM NaCl) (Table 5). The vermicompost treatments not only improved the production of total carotenoid under saline-free conditions, but also successfully amelio- rated the adverse effects caused by the salinity stress treatments on the plants (Table 5). The content of carotenoid increased in the vermicompost-treated plants grown with the 20% level by 1.30% compared to that in the control plants. Carotenoids act as * In each variable, data followed by the same letters (small letters for interactions and capital letters for means) are not significantly dif- ferent using LSD at 5%level. Data represent the mean value ± S.D. the mean of four replicates. Table 5 - Effect of salinity and vermicompost and their interaction on chlorophyll content, total carotenoid content and superoxide dismutase Vermicompost (%) Salinity (mM) Mean vermicompost 0 50 100 150 200 Chlorophyll content (mg g‐1 F.W.) 0 2.09±0.11 k 2.06±0.11 l 1.97±0.11 m 1.77±0.11 r 1.46±0.11 v 1.87±0.26 E 5 2.17±0.11 g 2.14±0.11 i 2.05±0.11 l 1.85±0.11 p 1.54±0.11 u 1.95±0.26 D 10 2.24±0.11 e 2.21±0.11 f 2.12±0.11 j 1.92±0.11 o 1.60±0.11 t 2.02±0.26 C 15 2.27±0.11 d 2.24±0.11 e 2.15±0.11 h 1.95±0.11 n 1.64±0.11 s 2.05±0.26 B 20 2.44±0.11 a 2.41±0.11 b 2.32±0.11 c 2.12±0.11 j 1.81±0.11 q 2.22±0.26 A Mean salinity 2.24±0.15 A 2.21±0.15 B 2.13±0.15 C 1.92±0.15 D 1.61±0.15 E Total carotenoid content (μg∙g‐1 F.W.) 0 12.48±0.92 k 12.46±0.92 l 12.43±0.92 o 12.35±0.92 r 7.82±0.92 w 11.51±2.06 E 5 12.50±0.92 i 12.49±0.92 j 12.45±0.92 m 12.37±0.92 q 7.84±0.92 v 11.53±2.06 D 10 12.52±0.92 f 12.51±0.92 h 12.48±0.92 k 12.40±0.9 2p 7.87±0.92 u 11.55±2.06 C 15 12.57±0.92 d 12.55±0.92 e 12.52±0.92 g 12.44±0.92 n 7.91±0.92 t 11.60±2.06 B 20 12.63±0.92 a 12.61±0.92 b 12.58±0.92 c 12.50±0.92 i 7.97±0.92 s 11.66±2.06 A Mean salinity 12.54±0.82A 12.52±0.82 B 12.49±0.82 C 12.41±0.82 D 7.88±0.82 E Superoxide dismutase (Ug‐1 F.W.) 0 146.00±1.92 m 152.00l±1.92 m 156.00±1.92 kl 440.00±1.92 d 104.00±1.92 q 199.60±1.25 C 5 155.50±0.80 kl 161.50±0.80 ijk 165.50±0.80 ghi 449.50±0.80 c 113.50±0.80 p 209.10±1.24 B 10 15.50±0.80 jkl 163.50±0.80 hij 167.50±0.80 f-i 451.50±0.80 bc 115.50±0.80 o 211.10±1.24 B 15 163.50±0.80 hij 169.50±0.80 e-h 173.50±0.80 ef 457.50±0.80 ab 121.50±0.80 n 217.10±1.24 A 20 165.50±0.80 ghi 171.50±0.80 efg 175.50±0.80 e 459.50±0.80 a 123.50±0.80 n 219.10±1.24 A Mean salinity 157.60±1.22 D 163.60±1.22 C 167.60±1.22 B 451.60±1.22 A 115.60±1.22 E Adv. Hort. Sci., 2019 33(3): 345-358 352 helper pigments in chloroplasts, but their most important role is antioxidant properties. Because of the oxidative stress caused by salinity stress in plant tissues, carotenoid activity in both antioxidant enzy- matic and non-enzymatic systems decrease (Pant et al., 2009). In similar studies in summer savory (Satureja hortensis L.) (Najafi and Khavari-Nejad, 2010), wheat (Triticum vulgare L.) (Reddy and Vora, 2005), and marjoram (Origanum majorana) (Baatour et al., 2010), reduction of carotenoids under salinity conditions has been reported. In a study consistent with the findings of the present study, Ayyobi et al. ( 2 0 1 4 ) s t a t e d t h a t v e r m i c o m p o s t i n c r e a s e d carotenoid content in peppermint (Mentha piperita L.) leaves. Enzyme activities The activities of APX, POD, CAT and SOD in pot marigold plants were significantly affected by the salinity stress and vermicompost treatments. With the increasing extent of salinity stress, the activities of APX, POD, CAT and SOD increased markedly and then significantly decreased (Table 5 and 6). APX, POD, CAT and SOD enzyme activities increased (12.08%, 13.67%, 36.08% and 186.54%, respectively) in the plants at salinity level of 150 mM NaCl com- pared to those in the control plants. Usually one of the biochemical changes that occur in plants under stress conditions is the accumulation of reactive oxy- gen species such as superoxide, hydrogen peroxide, and radical hydroxyl, all of which are highly toxic and reactive, and disrupt the normal metabolism of the cells. These radicals create secondary oxidative stress, through peroxidation of lipids, resulting in membrane degradation, protein degradation, deacti- vation of enzymes, elimination of pigments, and dis- ruption of DNA, leading to serious damage to the structure of cells and eventually to the whole plant. One strategy of plants to counteract this stress is the accumulation of antioxidant enzymes (Kang et al., 2014). Similar results have been reported in pot marigold (Calendula officinalis L.) (Hemmati et al., 2018) and chickpea (Cicer arietinum L.) (Sadak et al., 2017). The vermicompost treatments significantly enhanced the activities of APX, POD, CAT and SOD under salinity stress conditions, and the increases in the activities of APX, POD, CAT and SOD were 2.90%, 21.08%, 2.41% and 9.76% in the plants under the 20% vermicompost treatment compared with those in the control plants (Table 5 and 6). Similar results Table 6 - Effect of salinity and vermicompost and their interaction on catalase, peroxidase and ascorbate peroxidase * In each variable, data followed by the same letters (small letters for interactions and capital letters for means) are not significantly dif- ferent using LSD at 5%level. Data represent the mean value ± S.D. the mean of four replicates. Salinity (mM) Sanility Mean vermicompost 0 50 100 150 200 Catalase (Ug‐1 F.W.) 0 31.65±1.58 r 31.85±1.58 p 32.16±1.58 m 43.18±1.58 e 20.78±1.58 w 31.92±7.4 E 5 31.80±1.58 q 32.00±1.58 o 32.31±1.58 k 43.33±1.58 d 20.93±1.58 v 32.07±7.4 D 10 31.85±1.58 p 32.05±1.58 n 32.36±1.58 j 43.38±1.5 8 c 20.98±1.58 u 32.13±7.4 C 15 32.05±1.58 n 32.26±1.58 l 32.56±1.58 h 43.58±1.58 b 21.19±1.58 t 32.33±7.4 B 20 32.41±1.58 i 32.61±1.58 g 32.92±1.58 f 43.94±1.58 a 21.54±1.58 s 32.69±7.4 A Mean salinity 31.95±1.43 D 32.16±1.43 C 32.46±1.43 B 43.48±1.43 A 21.08±1.43 E Peroxidase (Ug‐1 F.W.) 0 68.40±0.93 o 69.07±0.93 no 70.80±0.93 mn 78.62±0.93 gh 41.48±0.93 t 65.68±12.99 E 5 70.75±3.98 nm 71.42±3.98 lm 73.15±3.98 kl 80.97±3.98 ef 43.83±3.98 s 68.03±13.43 D 10 75.03±3.98 jk 75.71±3.98 ij 77.44±3.98 hi 85.26±3.98 c 48.12±3.98 r 72.31±13.43 C 15 77.59±3.98 hi 78.27±3.98 gh 80.00±3.98 fg 87.82±3.98 b 50.67±3.98 q 74.87±13.43 B 20 82.25±3.98 ef 82.93±3.98 de 84.66±3.98 cd 92.48±3.98 a 55.33±3.98 p 79.53±13.43 A Mean salinity 74.80±5.96 C 75.48±5.96 C 77.21±5.96 B 85.03±5.96 A 47.89±5.96 D Ascorbate peroxidase (Ug‐1 F.W.) 0 869.60±1.51 s 875.40±1.51 q 880.40±1.51 n 976.10±1.51 e 459.60±1.51 x 812.20±1.85 E 5 873.20±1.51 r 878.90±1.51 p 883.90±1.51 m 979.60±1.51 d 463.20±1.51 w 815.80±1.85 D 10 879.60±1.51 o 885.40±1.51 l 890.40±1.51 k 986.10±1.51 c 469.60±1.51 v 822.20±1.85 C 15 885.40±1.51 l 891.10±1.51 j 896.10±1.51 h 991.80±1.51 b 475.40±1.51 u 827.90±1.85 B 20 893.20±1.51 i 898.90±1.51 g 903.90±1.51 f 999.60±1.51 a 483.20±1.51 t 835.80±1.85 A Mean salinity 880.20±1.6 D 885.90±1.6 C 890.90±1.6 B 986.60±1.6 A 470.20±1.6 E Adamipour et al. ‐ Effect of vermicompost on performances of pot marigold 353 have been reported in cowpea(Vigna unguiculata), rice (Oryza sativa L.), and tall fescue (Festuca arundi‐ nacea Schreb.) (Cavalcanti et al., 2004; García et al., 2014; Adamipour et al., 2016). Nutrients in leaf tissue N, P, K, Fe, Mg and Zn concentrations significantly declined by the increasing salinity stress level from 0 to 200 mM NaCl (Table 7 and 8). Their concentrations Table 7 - Effect of salinity and vermicompost and their interaction on nitrogen, phosphorus and potassium Table 8 - Effect of salinity and vermicompost and their interaction on zinc, magnesium and iron * In each variable, data followed by the same letters (small letters for interactions and capital letters for means) are not significantly dif- ferent using LSD at 5%level. Data represent the mean value ± S.D. the mean of four replicates. Vermicompost (%) Salinity Mean vermicompost 0 50 100 150 200 Nitrogen (%) 0 2.01±0.04 ghi 1.99±0.01 hi 1.90±0.01 j 1.01±0.01 op 0.97±0.01 q 1.58±0.49 E 5 2.03±0.02 g 2.02±0.009 gh 1.93±0.009 j 1.04±0.009 o 1.00±0.009 pq 1.60±0.49 D 10 2.15±0.04 e 2.10±0.01 f 2.01±0.01 ghi 1.12±0.01 m 1.08±0.01 n 1.69±0.49 C 15 2.40±0.08 c 2.38±0.02 c 2.29±0.02 d 1.40±0.02 k 1.36±0.02 l 1.97±0.49 B 20 3.01±0.02 a 2.99±0.01 a 2.90±0.01 b 2.01±0.01 gh 1.97±0.01 i 2.58±0.49 A Mean salinity 2.32±0.38 A 2.30±0.38 B 2.21±0.38 C 1.32±0.38 D 1.28±0.38 E Phosphorus (%) 0 0.15±0.005 ijk 0.14±0.005 lm 0.12±0.005 no 0.11±0.005 p 0.08±0.005 r 0.12±0.02 E 5 0.15±0.006 hi 0.15±0.006 jkl 0.13±0.006 mn 0.11±0.006 op 0.09±0.006 qr 0.13±0.02 D 10 0.16±0.009 gh 0.15±0.009 ij 0.14±0.009 klm 0.12±0.009 no 0.10±0.009 q 0.13±0.02 C 15 0.19±0.006 e 0.18±0.006 f 0.16±0.006 g 0.15±0.006 ij 0.12±0.006 no 0.16±0.02 B 20 0.24±0.005 a 0.23±0.005 b 0.22±0.005 c 0.20±0.005 d 0.18±0.005 f 0.22±0.02 A Mean salinity 0.18±0.03 A 0.17±0.03 B 0.15±0.03 C 0.14±0.03 D 0.11±0.03 E Potassium (%) 0 3.93±0.14 fgh 3.89±0.14 ghi 3.84±0.14 hi 2.93±0.14 mn 2.11±0.14 p 3.34±0.74 D 5 4.11±0.18 d-h 4.07±0.18 d-h 4.02±0.18 e-h 3.11±0.18 lm 2.29±0.18 op 3.52±0.75 C 10 4.22±0.12 de 4.18±0.12 def 4.13±0.12 d-g 3.22±0.12 kl 2.40±0.12 o 3.63±0.74 C 15 4.63±0.22 b 4.59±0.22 bc 4.54±0.22 bc 3.63±0.22 ij 2.81±0.22 n 4.04±0.76 B 20 5.32±0.31 a 5.28±0.31 a 5.23±0.31 a 4.32±0.31 cd 3.50±0.31 jk 4.73±0.78 A Mean salinity 4.44±0.54 A 4.40±0.54 A 4.35±0.54 A 3.44±0.54 B 2.62±0.54 C * In each variable, data followed by the same letters (small letters for interactions and capital letters for means) are not significantly dif- ferent using LSD at 5%level. Data represent the mean value ± S.D. the mean of four replicates. Vermicompost (%) Salinity Mean vermicompost 0 50 100 150 200 Zn (mg/kg) 0 91.47±0.47 efg 91.42±0.47 fg 91.34±0.47 fg 90.35±0.47 i 88.88±0.47 k 90.69±1. 10E 5 91.78±0.51 def 91.73±0.51 def 91.65±0.51 def 90.66±0.51 hi 89.19±0.51 jk 91.00±1. 10D 10 92.14±0.32 d 92.09±0.32 d 92.01±0.32 de 91.02±0.32 gh 89.55±0.32 j 91.36±1. 06C 15 93.25±0.86 c 93.20±0.86 c 93.12±0.86 c 92.13±0.86 d 90.66±0.86 hi 92.47±1. 28B 20 95.44±0.51 a 95.39±0.51 a 95.31±0.51 a 94.32±0.51 b 92.85±0.51 c 94.66±1. 11A Mean salinity 92.82±1. 56 A 92.77±1. 56 A 92.69±1. 56 A 91.70±1. 56 B 90.23±1. 56 C Mg (mg/kg) 0 1.69±0.09 efg 1.64±0.09 e-h 1.60±0.09 e-h 1.46±0.09 ghi 1.23±0.09 i 1.52±0.18 D 5 1.72±0.06 efg 1.69±0.06 efg 1.65±0.06 e-h 1.51±0.06 f-i 1.28±0.06 i 1.57±0.17 CD 10 1.82±0.12 cde 1.79±0.12 c-f 1.75±0.12 d-g 1.61±0.12 e-h 1.38±0.12 i 1.67±0.20 C 15 2.10±0.20 c 2.07±0.20 c 2.03±0.20 cd 1.89±0.20 cde 1.66±0.20 e-h 1.95±0.24 B 20 3.38±0.58 a 3.35±0.58 a 3.31±0.58 a 3.17±0.58 ab 2.94±0.58 b 3.23±0.54 A Mean salinity 2.14±0.70 A 2.11±0.70 A 2.07±0.70 A 1.93±0.70 B 1.70±0.70 C Fe (mg/kg) 0 122.05±1.68 ij 121.92±1.68 ij 120.69±1.68 j 115.50±1.68 k 100.27±1.68 m 116.09±8.60 E 5 124.19±1.96 hi 124.06±1.96 i 122.83±1.96 ij 117.64±1.96 k 102.41±1.96 m 118.23±8.65 D 10 128.42±2.33 g 128.29±2.33 g 127.06±2.33 gh 121.87±2.33 ij 106.64±2.33 l 122.45±8.72 C 15 154.19±2.69 d 154.06±2.69 d 152.83±2.69 d 147.64±2.69 e 132.41±2.69 f 148.23±8.80 B 20 196.53±4.15 a 196.40±4.15 a 195.17±4.15 a 189.98±4.15 b 174.75±4.15 c 190.56±9.24 A Mean salinity 145.07±29.02 A 144.94A±29.02B 143.71±29.02 B 138.52±29.02 C 123.29±29.02 D Adv. Hort. Sci., 2019 33(3): 345-358 354 decreased (44.82%, 36.06%, 40.99%, 15.01%, 20.56% and 2.79%, respectively) in the plants at 200 mM NaCl compared to those in the control plants. N, P, K, Fe, Mg and Zn concentrations in the leaf tissues of pot marigold increased significantly with increasing vermicompost composition in the media compared to those in the control plants. The highest and the l o w e s t c o n c e n t r a ti o n s o f t h e e l e m e n t s w e r e observed in the 20% and the 0% vermicompost treat- ments, respectively (Table 7 and 8). Furthermore, N, P , K , F e , M g a n d Z n c o n c e n t r a ti o n s i n l e a v e s increased 46.20%, 80.32%, 4.61%, 64.14%, 112.50%, and 4.37% in the plants with the 20% vermicompost treatment compared to those in plants with the con- trol treatment, respectively. Interaction between the levels of salinity and vermicompost resulted in the highest and the lowest nutrient concentrations in the plants with the 0 mM NaCl and 20% vermicompost and with the200 mM NaCl and 0% vermicompost treatments, respectively (Table 7 and 8). Plant growth is reduced in salt-affected soil because of the excess uptake of potentially toxic ions. Soil salinity is characterized by high amounts of Na, Mg, Ca, Cl, HCO3 - and B ions in soil which have negative effects on plant growth. Eventually, high salt concentrations in soil reduce the absorption of nutrients of plants which negatively affects the fertility of the soil (Zhao and Ren, 2007). In this study, the increase of vermi- compost levels increased the mineral nutrition. Vermicompost contains humic substances that have multiple effects in the soil. It may improve soil prop- erties such as micronutrient transport and availability (Aşık et al., 2009). Chen and Aviad (1990) summa- rized the effects of humic substances on plant growth and mineral nutrition, pointing out the positive effects on the uptake of macro- (such as N, P, and K) and micro-elements. Vermicompost may enhance the uptake of nutrients and reduce the uptake of some toxic elements of plants under salinity stress conditions. Chamani et al. (2008) reported that addi- tion of vermicompost to soils resulted in increased mineral contents in the substrate and higher concen- trations P, Ca, Mg, Cu, Mn and Zn in shoot tissues of red clover and cucumber. Correlation analysis The results of the Pearson correlation analysis between vermicompost abundance and the measu- red morphological traits and elements showed a positive and significant correlation. Therefore, a posi- tive relation between the increases of the amount of vermicompost and improvement in the morphologi- cal traits and measured elements can be inferred. According to the results, shoot fresh weight compa- red to shoot dry weight (r=0.89**) and flower diame- ter (r=0.57**) showed the highest and the lowest cor- relations among the morphological traits, respecti- vely (Table 9). In the measured elements under the vermicompost treatments, the highest correlation was observed between shoot fresh weight and K con- tent (r=0.81**) while the lowest correlation was seen in Mg content (r=0.67**) (Table 9). This improvement can be attributed to the presence of macro-micro elements, the release of elements in the soil and soil amendment of physical and biological conditions which have been previously reported in other plants Table 9 - Correlation coefficients for evaluated traits on pot marigold in vermicompost treatment Traits Shoot FW Shoot DW Leaf area Root FW Root DW Flower diameter Fruit FW Fruit DW Zn Fe Mg Ca K P N Shoot FW 1 Shoot DW 0.891** 1 Leaf area 0.886** 0.992** 1 Root FW 0.798** 0.799** 0.777** 1 Root DW 0.798** 0.799** 0.777** 1.00** 1 Flower diameter 0.574** 0.603** 0.586** 0.519* 0.519* 1 Fruit FW 0.811** 0.795** 0.801** 0.618** 0.618** 0.334 NS 1 Fruit DW 0.618** 0.728** 0.695** 0.734** 0.734** 0.536* 0.417 NS 1 Zn 0.789** 0.883** 0.875** 0.864** 0.864** 0.623** 0.778** 0.722** 1 Fe 0.809** 0.836** 0.822** 0.825** 0.825** 0.624** 0.818** 0.686** 0.951** 1 Mg 0.679** 0.797** 0.781** 0.764** 0.764** 0.538* 0.733** 0.749** 0.927** 0.907** 1 Ca 0.789** 0.883** 0.875** 0.864** 0.864** 0.623** 0.778** 0.722** 1.00** 0.951** 0.927** 1 K 0.818** 0.851** 0.842** 0.799** 0.799** 0.561** 0.778** 0.765** 0.911** 0.929** 0.884** 0.911** 1 P 0.815** 0.847** 0.835** 0.815** 0.815** 0.554* 0.831** 0.698** 0.937** 0.981** 0.921** 0.937** 0.938** 1 N 0.805** 0.834** 0.814** 0.831** 0.831** 0.604** 0.810** 0.704** 0.956** 0.989** 0.933** 0.956** 0.916** 0.981** 1 FW = fresh weight; DW= dry weight. NS= Not significant, * and **: Significant at 5% and 1% respectively. Adamipour et al. ‐ Effect of vermicompost on performances of pot marigold 355 (Bachman and Metzger, 2008). In this correlation analysis, peroxidase activity (r=0.79**) and proline content (r=0.44**) had the highest and the lowest correlations with shoot fresh weight. Further, insigni- ficant correlations were observed in carotenoid con- tent and catalase enzyme activity (Table 10). It see- med the positive correlations in activities of antioxi- dant enzymes, chlorophyll and proline content in the plant was due to increased concentrations of the ele- ments which could be provided by vermicompost. Because in the structure of the mentioned traits, there are a variety of macro- and micro- elements that vermicompost provides directly and indirectly to plants (Hidalgo et al., 2006). The results of a simple correlation analysis between the morphological traits and the studied elements under salt stress conditions showed that shoot fresh weight had a positive and significant correlation with all the morphological indi- ces and concentration of elements. In this analysis, the highest and the lowest correlations were seen in leaf area (r=0.99**) and fresh flower weight (r=0.91**), respectively (Table 11). Also, the highest correlation of shoot fresh weight was observed in Fe content (r=0.98**) and the lowest correlation was found in N content (r=0.88**) (Table 11). There are many reports of positive correlations between plant yield and con- centration of elements under salinity stress condi- tions. Increase in soil pH, reduction in the amount of absorbent elements in the soil, increase in toxic ele- ments of soil such as Cl and Na, and osmotic stress in the soil that prevents water absorption are the most c r i ti c a l f a c t o r s f o r t h i s p h e n o m e n o n i n p l a n t s (Edwards et al., 2010). Analysis of correlations of shoot fresh weight with chlorophyll and proline con- Table 11 - Correlation coefficients for evaluated traits on pot marigold in salinity stress conditions Traits Shoot FW Shoot DW Leaf area Root FW Root DW Flower diameter Fruit FW Fruit DW Zn Fe Mg Ca K P N Shoot FW 1 Shoot dw 0.939** 1 Leaf area 0.995** 0,956** 1 Root FW 0.966** 0.886** 0.961** 1 Root dw 0.923** 0.868** 0.921** 0.986** 1 Flower diameter 0.986** 0.977** 0.991* 0.952** 0.919** 1 Fruit FW 0.918** 0.830** 0.906** 0.844** 0.798** 0.865** 1 Fruit dw 0.942** 0.947** 0.948** 0.901** 0.855** 0.972** 0.779** 1 Zn 0.938** 0.947** 0.956** 0.850** 0.802** 0.941** 0.923** 0.892** 1 Fe 0.985** 0.940** 0.987** 0.914** 0.851** 0.977** 0.909** 0.948** 0.963** 1 Mg 0.895** 0.910** 0.803** 0.762** 0.897** 0.919** 0.856** 0.969** 0.912** 0.857** 1 Ca 0.938** 0.947** 0.956** 0.850* 0.802** 0.941** 0.923** 0.892** 1.00** 0.963** 0.969** 1 K 0.981** 0.961** 0.991* 0.954** 0.928** 0.982** 0.915** 0.927** 0.966** 0.967** 0.932** 0.966** 1 P 0.936** 0.877** 0.911** 0.933** 0.926** 0.919** 0.843** 0.858** 0.804** 0.879** 0.756** 0.804** 0.894** 1 N 0.885** 0.870** 0.892** 0.941** 0.976** 0.886** 0.809** 0.796** 0.831** 0.811** 0.781** 0.923** 0.817** 0.891** 1 FW = fresh weight; DW= dry weight. NS= Not significant, * and **: Significant at 5% and 1% respectively. Table 10 - Correlation coefficients for evaluated traits on pot marigold under salinity stress conditions (above diameter) and vermicom- post treatment (below diameter) NS= Not significant, * and **: Significant at 5% and 1% respectively. Traits Shoot fresh weight Chlorophyll Proline Carotenoid Ascorbate perodidase Peroxidase Catalase Superoxide dismutase Shoot fresh weith 1 0.913 ** -0.904 ** -0.874 ** 0.872 ** 0.990 ** 0.905 ** 0.861** Chlorophyll 0.664 ** 1 -0.992 ** 0.857 ** -0.856 ** 0.888 ** 0.888 ** 0.626** Proline 0.444 ** 0.176 NS 1 0.854 ** 0.680 ** -0.816 ** 0.714 ** 0.571** Carotenoid 0.059 NS 0.488 * 0.454 * 1 0.801 ** 0.651 ** -0.544 * -0.346 NS Ascorbate peroxidase 0.490* 0.064 NS 0.038 NS -0.435 NS 1 0.760 ** 0.407 NS -0.085 NS Peroxidase 0.794 ** 0.480 * 0.540 * 0.093 NS 0.746 ** 1 0.458* -0.020 NS Catalase 0.131 NS 0.444 * -0.341 NS 0.252 NS 0.430 NS 0.317 NS 1 -0.006 NS Superoxide dismutase 0.514 * 0.793 ** -0.210 NS 0.131 NS -0.002 NS 0.241 NS 0.355 NS 1 Adv. Hort. Sci., 2019 33(3): 345-358 356 tent, and antioxidant enzyme activity showed signifi- cant positive and negative correlations. From the viewpoint of biochemistry, most of significant corre- l a ti o n s w e r e f o u n d i n c o n t e n t o f c h l o r o p h y l l (r=0.91**), proline (r= -0.90**), carotenoid (r= -0.87**), in activity of ascorbate peroxidase (r=0.87**), peroxi- dase (r=0.99**), catalase (r=0.90**), and superoxide dismutase (r=0.86**) compared to the shoot fresh weight (Table 10). There were also few negative cor- relations in which proline and carotenoid content can be attributed to their function in dealing with osmo- tic stress in the plants due to increased salinity in the soil. In similar studies, positive correlation of antioxi- dant enzyme activity under salinity stress conditions in German chamomile (Matricaria recutita L.), sun- flowers (Helianthus annuus L.) and basil (Ocimuum basilicum L.) have been reported (Baghalian et al., 2008; Heidari et al., 2011; Heidari, 2012). 4. Conclusions Salinization of soil is a serious land degradation problem and is increasing steadily in many parts of the world, particularly in arid and semiarid areas. Soil salinity affects the establishment, growth, and devel- opment of plants leading to huge losses in productivi- ty. Vermicompost is one of the major organic fertiliz- er which can improve growth and salinity tolerance with containing plenty nutrition elements, hormones, and organic materials. In this study, increase in salini- ty stress significantly led to decline in morphological and physiological indices of pot marigold. Application of vermicompost under salinity conditions increased m o r p h o - p h y s i o l o g i c a l i n d i c e s i n t h i s p l a n t . Vermicompost increased the activity of the antioxi- dant system, the content of proline and chlorophyll in the plant by increasing the nutrients in the soil environment that could increase the plant yield and alleviating the harmful effects of salinity. 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