Investigation of Growth and Biomass Response of Five Tree Species under Irrigation with Compost Leachate

Abstract

In this study, the growth and biomass of Populus deltoides Marshall., Alnus glutinosa (L.) Gaertn., Populus euramericana Guinier., Salix alba L. and Taxodium distichum (L.) Rich. were analyzed with compost leachate irrigation. Cuttings were collected at the beginning of the growing season and planted in pots with 40 cm depth in Safrabasteh Poplar Research Centre in Guilan Province, Iran. Three treatments were used consist of: tap pure compost leachate (P), water (control), and water to compost ratio of 1:1 (50% water + 50% compost leachate) treatments. Biomass and growth parameters including height, diameter, aboveground and underground biomass were calculated at the end of growing season. The results show that highest diameter growth was observed in T. distichum and A. glutinosa with compost leachate treatment and also showed the highest amount of height growth in tap water and 1:1 treatment. The highest absorption of elements in aboveground and root biomass was observed in T. distichum, A. glutinosa and P. euramericana with 1:1 treatment. According to results of this study, it is concluded that plants absorption of leachate elements can be used as an attractive method to reduce damages to the soil and ecosystem and in consequence increase the quality of life.

1. Introduction

Various pollutants such as ammonia, nitrogen, heavy metals, inorganic salts and chlorinated organic materials have been exposed to leachates [1]. The increase in solid waste in cities has encouraged resource managers to use plant/soil systems to treat landfill leachates before discharge [2]. Untreated leachate discharge, such as leachate components, hazardous contamination or water eutrophication, can be harmful to the environment [3]. Due to the high amount of contaminants, leachate treatment demonstrates an enormous cost in solid waste management to reach prescribed emission standards [4]. Traditional intensive forestry and waste management provide several goals such as bioenergy production, soil/water remediation and carbon sequestration [5].

One of the technology to landfill rededications is phytoremediation, and it can both stabilize soil and remediate landfill leachate by using plants abilities to accumulate toxic contaminants [6]. The phytoremediation principle is to match the suitable species to the contaminated sites regarding the soil and microclimate conditions [7]. Phytoremediation is accepted as an alternative solution to conventional engineering methods due to its several advantages such as cost-effective, environmentally friendly and less damaging to the soil and ecosystem [6].

Phytoremediation has long been employed for leachate treatment around the world [2, 4, 5, 8, 9, 10]. For example, Guidi Nissim et al. [11] report the results of a two-year project where poplar and willow grown in mesocosm were tested for their ability to withstand and remove specific pollutants from different (Low: 7% and High 15%) amounts of landfill leachate. Poplar showed, on average, significantly higher extraction rates for Cd, Cu, P and N than willow. Moreover, under high landfill leachate treatment, poplar also seemed more efficient than willow in decreasing the concentration of specific pollutants (BOD and COD) in output effluent. Lucero-Sobarzo et al. [4] performed a field trial on a real scale by landfill leachate used as a source of nutrients for the growth of maize by precipitation of struvite. Marginal higher maize yield was achieved in two sites (6.36% and 2.16%) compared to the commercial fertilizer. Struvite did not cause the presence of pathogens or heavy metals in the crops. The aim of Koda et al. [12] work was to find the relationship between the composition and leachate seepage points and determine the possibilities of their practical utilization for the assessment of the applied mineral sealing of landfill surfaces. The results indicate that the presence of leachates alters the plant species composition. The composition shows increasing representation of species tolerant to salinization. Shabir et al. [13] introduced Acacia nilotica as a phytoremediation potential species in cadmium-contaminated soil with saline and non-saline conditions in Pakistan. Askary et al. [14] also showed the potential effect of petroleum pollution of soil (0%, 1%, 2%, 3% and 4% V/W) on the proline, total protein, lead, cadmium and zinc contents in Robinia pseudoacacia L. leaves. Based upon these results, R. pseudoacacia L. can be used as bioaccumulation in petroleum pollution and was selected for further investigation of the phytoremediation of pb-contaminated soil. Alizadeh et al. [15] investigated the influence of soil amendment on cadmium accumulation responses in one-year-old Populus alba L. seedling. The results indicated that higher biomass productions in amended substrates compared to control led to an increase of total cadmium uptake two times more than that in the control substrate at 150 mg kg-1 cadmium supply. In some cases, there was no significant difference in cadmium accumulations among substrates. Sammons and Struve [5] investigated the effects of near-zero leachate irrigation on growth and water-use efficiency and nutrient uptake of container-grown baldcypress (Taxodium distichum (L.) Rich.) plants. Results show root dry mass ratios and fertilizer and irrigation interaction did not affect water-use efficiency. The higher fertilizer rate increased the whole plant N and K concentrations. Plant tissue mineral nutrient concentrations and water-use efficiency increased.

Zalesny et al. [9] mentioned Populus as an ideal species for phytoremediation because of their extensive root systems, fast growth and high-water usage rate. Several approaches have been developed to improve the tolerance and/or accumulation of Potentially Toxic Elements (PTEs) in the plant.

This study aims to compare the growth and biomass of different species with regard to different concentrations of compost leachate from green and municipal organic waste. The study objectives were to:

• Assessing the growth in diameter and height of species using leachate irrigation

• Determining the amount of aboveground and root biomass under compost leachate irrigation treatments

2. Materials and methods

The study was conducted in Poplar Research Centre of Safrabasteh in the eastern part of Gilan Province at Northern part of Iran (37° 19’N, 49° 57′E). In this research, five different species namely, P. deltoides 69/55, Populus euramericana I-sieres, S. alba, A. glutinosa and T. distichum were selected. The cuttings were collected from the nursery in the middle of March with the length of 20 cm from 1-year old saplings and planted in pots with 40 cm depth in sandy-loam soil.

The compost leachates were collected from the collection reservoir, which contains organic municipal waste, gardening and plant waste. The collection reservoir is located in the Compost Plant of Municipal Waste Management of Rasht (37° 10’N, 49° 34′E), Northern part of Iran. The leachate color was dark brown and had a putrid odour. The leachate was analyzed in the Laboratory of Guilan Department of Environment (Rasht, Iran) using approved Standard Methods for the Examination of Water and Wastewater (Table 1) [16].

Parameter	Unit	Amount
pH	—	5.22
EC	mS cm-1	1.26
N total	mgL-1	21.384
NO2	mgL-1	0.08
NO3	mgL-1	21.3
SO4	mgL-1	7101
PO4-P	mgL-1	22.11
Na	mgL-1	310
K	mgL-1	250
Ca	mgL-1	152
Mg	mgL-1	1103
Pb	mgL-1	0.27
Ni	mgL-1	0.342
Cd	mgL-1	0.0047
Cr	mgL-1	Trace
COD	mgL-1	260,500
BOD	mgL-1	130,000
TSS	mgL-1	3060.6
Turbidity	mgL-1	12,500

Table 1.

Composition of pure compost leachate.

Three different treatments of irrigation were applied on each species, with five replicates for plant growth and three replicates for biomass and elements (the number of replicates for biomass and elements was limited due to the high costs of laboratory analysis). Three treatments consist of:

P (Pure compost leachate).

1:1 ratio (50% water +50% compost leachate).

Tap water (Control).

Water (control) from the study area was applied to all cuttings via hand irrigation for a settlement period of eight weeks. After the settlement, experiments were started in the middle of May with either leachate, water or 1:1 (50% water +50% compost leachate) treatment and lasted till December. The plants were irrigated with the respective water mixtures to the water holding capacity of the substrate in the pot (0.5 L per pot) in the first weeks of the experiment. With the growth of the plants, the amount of water added in a daily irrigation event was adjusted to the plant’s demands. Pure leachate was the leachate without dilution. The tap water for treatment (C) and for the preparation of the water mixtures was used from the public drinking water supply.

The sapling growth (diameter and height) was monitored bimonthly and recorded. The diameter growth was measured from the sprout-out of the principal shoot, and the height growth was measured from ground level to the base of the apical bud on the terminal shoot of 125 seedlings.

All seedlings were harvested in December at the end of the growing season. The harvested saplings were divided into two portions as, aboveground (leaf + stem) and underground (root section). Root systems were washed carefully to remove soil particles, and then all the plant sections were dried at 70°C.

Root and groundmass fractions were calculated as the ratio between belowground dry mass, aboveground dry mass and total tree dry mass [10]. The amount of elements such as N, P, K and Ca at both aboveground and underground sections were measured with three replicates. Total N analyses with Kjeldahl method, P with Olsen and Sommers [17] for details on the Na2CO3 fusion method and K with flame photometric method. Soil experiments were performed according to the instructions for laboratory analysis of soil samples of the Soil and Water Research Institute.

The experiments were arranged in randomized complete design with five species and five replicates of each treatment for plant growth parameters and three replicates for biomass and elements. The data were analyzed using SAS and Analysis of Variance (ANOVA) to analyze the differences between treatments of each plant species and between the plant species for each treatment. Tukey HSD test was carried out for differences between means that were considered at different probability values of P < 0.05.

3. Results

The leachate characteristics are shown in Table 1.

A one-way ANOVA was conducted to compare the effect of irrigation treatments on plant height in pure compost leachate (P), 1:1 (50% leachate and 50% water) and tap water (Control) conditions. The results showed that there was a significant effect of irrigation treatments on plant height (P < 0.0001), and there was a significant effect on plant height (P < 0.000) (Table 2).

Trait	Source of variations
	Treatment	Species	Treatment ×Species
Height (cm)	<0.0001	<0.0001	<0.0001
Diameter (cm)	<0.0001	<0.0001	<0.0001
Aboveground biomass (gr)	<0.0001	<0.0001	0.0054
Root biomass (gr)	0.0007	<0.0001	0.0208
Aboveground elements	<0.0001	<0.0001	<0.0001
Root elements	0.0011	<0.0001	<0.0001

Table 2.

Probability values from analysis of variance testing of the main effects of species, treatment and species ×treatment interaction on tree growth (height and diameter), biomass (aboveground and root biomass) and elements (aboveground and root) of five species irrigated with pure composite leachate, 1:1 (50% leachate and 50% water) and tap water.

Insignificant value is in bold.

Tukey test results between five species illustrate in Table 3.

Species	Treatment	Height (cm)	Diameter (cm)	Biomass component (gr)
				Aboveground	Root
P. deltoides	P	0 ± 0 g	0 ± 0f	0 ± 0e	0 ± 0d
	1:1	52.33 ± 1.63def	1 ± 0.12cde	20.42 ± 4.14bcde	1.14 ± 0.87c
	C	67.33 ± 7.56bcde	0.77 ± 0.1e	15.86 ± 11.37cde	1.05 ± 0.68bc
A. glutinosa	P	91.50 ± 10.62abc	2.05 ± 0.52a	39.53 ± 12.14ab	4.20 ± 1.77bc
	1:1	90.60 ± 12.70abc	1.58 ± 0.13abc	44.36 ± 8.05a	7.78 ± 1.12a
	C	112.80 ± 16.97a	1.98 ± 0.1ab	47.12 ± 11.49a	5.5 ± 1.78abc
Populus euramericana	P	32.30 ± 2.65efg	0.68 ± 0.08e	1.42 ± 0e	0.44 ± 0ab
	1:1	27.90 ± 12.42 fg	0.64 ± 0.18e	0.77 ± 0e	0.45 ± 0ab
	C	59.20 ± 19.07cdef	0.84 ± 0.19de	29.5 ± 11.85abcd	1.53 ± 0.18bc
S. alba	P	0 ± 0 g	0 ± 0f	0 ± 0e	0 ± 0d
	1:1	73.80 ± 12.56bcd	0.8 ± 0.2de	6.70 ± 2.97e	1.44 ± 0.47bc
	C	79 ± 13.53abcd	0.68 ± 0.13e	13.39 ± 4.59de	0.78 ± 0.32bc
Taxodium distichum	P	97.20 ± 5.40ab	1.68 ± 0.22ab	31.20 ± 6.38abcd	3.91 ± 0.61bc
	1:1	101 ± 16.81ab	1.53 ± 0.45abc	47.47 ± 11.85a	5.17 ± 1.66abc
	C	87.20 ± 19.97abcd	1.40 ± 0.28bcd	35.90 ± 9.41abc	2.75 ± 0.31ab

Table 3.

Final mean height, diameter and biomass components of five plants in three different treatments.

P, pure compost leachate; 50% leachate +50% water; C, tap water (control).

Mean values of zero show P. deltoides and S. alba seedlings have died in leachate treatment.

3.1 Seedlings growth

All pairwise mean comparisons were performed using the Tukey test between five species with a degree of significance of 0.05. Results showed that the highest average of seedlings height was 112.8 cm in A. glutinosa in tap water followed by 101 cm in T. distichum in 50% leachate +50% water treatment and the lowest average was 27.9 cm in P.euramericana (Table 3).

Diameter growth data were subjected to one-way ANOVA to test for differences among the five species. The ANOVA results showed that there was a significant difference between irrigation treatments (P < 0.0001) and species (P < 0.0001) on diameter growth (Table 3).

Tukey results explained the highest amount of diameter growth in tap water treatment was 2.05 cm (with no significant difference with 50% leachate +50% water treatment) for A. glutinosa, and the lowest amount was 0 in compost leachate treatment (P < 0.0001) for P. deltoides and S. alba in P treatment (Table 3).

3.2 Aboveground dry mass

ANOVA and Tukey procedures results showed a significant difference between species and treatment on aboveground dry mass (P < 0.0001) (Table 4). Comparing the mean aboveground dry mass between five plant species in treatments. A. glutinosa exhibited the maximum dry mass in all of the treatments (with the exception of 50% leachate +50% water treatment for T. distichum with 47.47 ± 11.85). S. alba exhibited the minimum dry mass with the exception of the 50% leachate +50% water treatment. 50% leachate +50% water treatment indicates the highest mean of N, P, K and Ca among the treatments (Table 4).

Species	Treatment	Aboveground elements(mg/kg)
		N	P	K	Ca
P. deltoides	P	0 ± 0d	0 ± 0b	0 ± 0 g	0 ± 0d
	1:1	5.16 ± 0.33a	0.36 ± 0.05a	5.85 ± 0.51a	5.95 ± 0.63abc
	C	3.69 ± abc	0.29 ± 0.01a	4.21 ± 0.36abc	6.1 ± 1abc
A. glutinosa	P	4.69 ± 1.14abc	0.27 ± 0.06a	2.4 ± 0.43def	5.33 ± 0.18bc
	1:1	5.38 ± 0.26a	0.25 ± 0a	1.13 ± 0.16 fg	4.62 ± 1.24c
	C	4.98 ± 0.31ab	0.25 ± 0.03a	1.46 ± 0.32efg	5.72 ± 0.58abc
Populus euramericana	P	4.77 ± 0ab	0.28 ± 0a	5.32 ± 0ab	6.52 ± 0abc
	1:1	3.82 ± 0abc	0.23 ± 0a	4.85 ± 0ab	7.52 ± 0ab
	C	3.08 ± 0.77bc	0.28 ± 0.06a	2.88 ± 0.67cde	7.1 ± 1.71abc
S. alba	P	0 ± 0d	0 ± 0b	0 ± 0 g	0 ± 0d
	1:1	5.36 ± 1.27a	0.29 ± 0.02a	3.71 ± 1bcd	8.35 ± 1.08a
	C	3.71 ± 0.7c	0.29 ± 0.02a	4.02 ± 0.95bcd	6.92 ± 1.62abc
Taxodium distichum	P	3.96 ± 0.2abc	0.29 ± 0.06a	5.14 ± 0.63ab	7.68 ± 1.27ab
	1:1	4.48 ± 0.59abc	0.34 ± 0.04a	5.34 ± 0.82ab	6.67 ± 0.31abc
	C	2.88 ± 0.74c	0.27 ± 0.06a	1.23 ± 0.65efg	6.97 ± 1.08abc

Table 4.

Mean of aboveground elements absorption of five species under irrigation treatments.

Different letters were significant at P < 0.05.

Zero number of mean show P. deltoides and S. alba seedlings have died in leachate treatment.

The amount of four elements, for example, N, P, K and Ca was analyzed in the aboveground section of seedlings after the growing period, and differences between treatments were tested by ANOVA followed by Tukey test using the SPSS with the effect of species, treatment and species × treatment on the elements. The results indicated that the effect of species (P < 0.0001), treatment (<0.0001), and species × treatment were significant on aboveground element absorption.

Tukey test determines that the mean score for the aboveground N element was significantly different between treatments, with the highest amount for 50% leachate +50% water treatment (M = 5.38). Comparing the mean N element between the five seedlings species in all treatments, A. glutinosa exhibited the greatest N (5.38) and followed by s. alba (5.36). P. deltoides and s. alba exhibited the lowest N (0).

The results of the aboveground mean P element showed a significant difference between treatments, with the highest amount for 50% leachate +50% water treatment (M = 0.36) and the lowest amount was achieved in compost leachate (M = 0) (P < 0.0001). Comparing the mean P element between the five plant species in all treatments, P. deltoides exhibited the greatest P (M = 0.36) and T. distichum (M = 0.34). S. alba exhibited the lowest it is (M = 0).

The mean score for the aboveground K element indicated a significant difference between treatments, with the highest amount for 50% leachate +50% water treatment (M = 5.85) and the lowest amount was achieved in compost leachate (M = 1.13) (P < 0.0001). Comparing the mean K element between the five plant species in all treatments, P. deltoides exhibited the greatest P (5.85), and A. glutinosa exhibited the lowest K (1.13).

Post hoc comparisons using Tukey test showed that the mean score for the aboveground Ca element was significantly different between treatments, with the highest amount for 50% leachate +50% treatment (M = 8.35) and the lowest amount was achieved in compost leachate (M = 4.62) (P < 0.0001). Comparing the mean Ca element between the five plant species in all treatments, s.alba exhibited the greatest Ca (8.35), and A. glutinosa exhibited the lowest Ca (4.62).

3.3 Root dry mass

Root dry mass results expressed there was a significant effect of irrigation treatment (P = 0.0007) and species (p < 0.0001). (Table 5).

Species	Treatment	Root elements (mg/kg)
		N	P	K	Ca
P. deltoides	P	0 ± 0 g	0 ± 0d	0 ± 0d	0 ± 0d
	1:1	1.62 ± 0.1cde	0.23 ± 0a	0.23 ± 0a	3.32 ± 0.29c
	C	1.15 ± 0.1ef	0.19 ± 0.02abc	0.19 ± 0.02abc	4.08 ± 0.73bc
A. glutinosa	P	2.24 ± 0.1abcd	0.12 ± 0.03c	1.13 ± 0.11b	4.26 ± 1.24bc
	1:1	2.53 ± 0.45ab	0.18 ± 0.05abc	0.28 ± 0.01c	5.98 ± 0.27a
	C	2.41 ± 0.17abc	0.16 ± 0.03abc	0.29 ± 0.01c	4.78 ± 0.78abc
Populus euramericana	P	1.58 ± 0cde	0.24 ± 0a	2.45 ± 0a	4.99 ± 0ab
	1:1	1.02 ± 0ef	0.22 ± 0ab	2.14 ± 0a	3.81 ± 0.71bc
	C	1.17 ± 0.19ef	0.24 ± 0.05a	2.35 ± 0a	3.91 ± 0.2bc
S. alba	P	0 ± 0 g	0 ± 0d	0 ± 0c	0 ± 0d
	1:1	1.82 ± 0.13bcde	0.24 ± 0.01a	2.36 ± 0.19a	3.81 ± 0.71bc
	C	1.43 ± 0.67def	0.29 ± 0.03a	2.55 ± 0.12a	3.92 ± 0.2bc
Taxodium distichum	P	2.93 ± 0.44a	0.22 ± 0.04ab	2.67 ± 0.49a	3.86 ± 0.82bc
	1:1	1.77 ± 0.52bcde	0.23 ± 0.03a	2.36 ± 0.22a	4.56 ± 0.91abc
	C	0.68 ± 0.16 fg	0.14 ± 0.02bc	0.24 ± 0.02c	5.17 ± 0.22ab

Table 5.

Mean of root elements absorption of five species under irrigation treatments.

Different letters were significant at P < 0.05.

Zero number of mean show P. deltoides and S. alba seedlings have died in leachate treatment.

Post hoc comparisons using Tukey test showed that the mean score for the root dry mass was significantly different between treatments with the highest amount of 50% leachate +50% water treatment (M = 7.78 gr) followed by water treatment with 5.5 gr (P < 0.0001), and the lowest amount was achieved 0 in compost leachate (Table 5). Comparing the mean root dry mass between the five plant species in all treatments, A. glutinosa and P. euramericana exhibited the greatest and lowest dry mass, respectively (Figure 1).

Figure 1.

Seedlings growth after irrigation treatments.

Mean of root elements absorption of five species under irrigation treatments demonstrate in Table 5. The amount of four elements, for example, K, N, P and Ca was analyzed in the root of plant species after the growing seasons, and the results analyzed with ANOVA with the effect of species, treatment, and species × treatment on the elements. ANOVA results showed that the effect of species (P < 0.0001) and treatment (<0.0001) was significant on root elements.

The highest average of N and Ca in the root system was found in A. glutinosa. P. euramericana root system showed the highest mean of P and K.

4. Discussion

In our study, seedlings height was negatively affected by leachate irrigation, and plant species showed higher plant height in irrigation treatments of tap water and 50% leachate +50% water. Diameter growth showed a better response to compost leachate than tap water. The 50% leachate +50% water treatment in this study showed a positive effect on dry root mass for aboveground than to leachate irrigation (P).

4.1 Seedlings growth

Regarding the plant species, the maximum amount of seedlings growth and biomass was shown in A. glutinosa and Taxodium distichum, whereas the maximum diameter and height growth occurred in (P) and (C) treatments for A. glutinosa followed by T. distichum. These two species also showed the maximum average of biomass compared to other species.

Many researchers around the world indicated the positive and negative effects of leachate irrigation on plant growth and biomass. For example, Rosenkranz [18] and Guidi Nissim et al. [11] found that the Salix sp. growth in controlled water was much better than plants irrigated with leachate. Zalesny and Bauer [1] also indicated that Populus clone NM6 had a better response to water treatment than leachate. The result is the same in this study about P. deltoides, all seedlings of P. deltoids died in pure leachate treatment.

In contrast, Justin et al. [19] found that landfill leachate positively affected Salix and Populus growth with increased biomass production. Zalesny et al. [20] and Zalesny et al. [21] also found a positive effect of compost leachate irrigation on Populus growth. Zalesny and Bauer [1] concluded that Salix clones S287 and S566 showed better growth rate with leachate irrigation. Alizadeh et al. [15] indicated the high biomass growth of Populus alba in cadmium treatments.

Dimitriou et al. [19] investigated the growth rate of five Salix clones after irrigation with three different landfill leachate (1:2, 1:3, 1:4, 1 unit of leachate and 2, 3, and 4 units of tap water) and found that plants irrigated with tap water has higher growth rate compared to plants irrigated with landfill leachate. Their study showed a significant difference between control plants and leachate irrigation and found insignificant difference between the other leachate concentrations. They concluded that the degree of dilution had a minor importance on plant growth.

The same result occurred in our study where plant diameter had developed in tap water with no significant difference in dilution degree. Therefore, the dilution degree showed a minor influence on plant diameter growth. However, the dilution degree showed a significant difference between tap water and 50% leachate +50% water concentration at the height of seedlings. Aboveground biomass responds the same trend as the diameter to different dilutions. In contrast, root mass positively responded to 50% leachate +50% water concentration more than other treatments. Therefore, the dilution degree showed a positive effect on root biomass. Therefore, small and non-significant differences between tap water plant growth parameters and dilution degree growth parameters showed that dilution of compost leachate could not be considered as a conventional means of fertilizer for mentioned species except for root biomass [21]. The plant roots in this study may have contributed to the greater availability of elements concentrated in leachate irrigation treatment resulting in higher root dry mass in leachate treatment compared to controlled water. Under a leachate irrigation that leachate volume would be decreased, leachate electrical conductivity values and water-use efficiency would be increased, and at recommended fertilizer rates plant growth would be decreased.

Plant growth predictions in leachate treatments are difficult to make. Biomass production and plant growth rate are suitable indicators of imposed stress [19]. In our study, significant differences between controlled water and leachate treatments (P) of seedlings growth and biomass (except for root biomass) indicate stress on plants treated with compost leachate. Plant growth processes are strongly related to the salt effects; therefore, plant growth rate indicates a suitable way to understand salt stress [22]. The measurement of chemical components of leachate in this study showed the highest amount of salt concentration, leading to less growth rate than other treatments.

4.2 Above ground and root dry mass

The differences between the concentration of leachate treatments in this study and other [23, 24, 25] and their effects on plant growth and biomass can be taken into account that the concentration of wastewater can be used in irrigation that depend on wastewater and soil, and the nutrient demand of plants [20]. Dimitriou et al. [19] mentioned that in Sweden, the leachate treated to Salix irrigation, the plants have either died or suffered. Therefore, designing leachate irrigation treatments on plant vitality and growth must be considered.

In this study, there was a significant difference between plant growth and biomass for leachate and tap water (control) in all species with the exception of root mass biomass (Table 4). Therefore, the higher amount of toxic concentrations in leachate treatment prevents the development of the species. P. deltoides and S. alba seedlings have died in leachate treatment (P), which can be considered a visual sign of stress in leachate treatment, leading to damage and destruction of species. This can be attributed to an imbalance of nutrients, low pH and high salinity in leachate treatment [7, 10, 24].

The amount of four elements, for example, N, P, K and Ca was analyzed in aboveground and root of plant species in different treatments. The highest absorption of elements was carried out by A. glutinosa, T. distichum and Populus euramericana in 50% leachate +50% water treatment, and the lowest amount was exhibited in leachate treatment (P). The lowest amount of element absorption by plant sections in leachate treatment (P) is due to the fact that increasing the salinity concentration in component leads to decreased concentrations of K, P and Ca [4]. Zalesny et al. [20] mentioned that landfill leachate could be used as fertilizer as some of the essential elements available in the components. Zalesny and Bauer [1] conducted that the concentration of wastewater which could be used as fertilizer depending on soil, wastewater and nutrient demand of plants. Therefore, in this study, 50% leachate +50% water treatment can be considered a conventional fertilizer. Licht and Isebrands [26] mentioned that plants grow better when irrigated with leachate containing all the essential plant nutrients, petrochemical organic compounds, and salts below toxicity thresholds.

In conclusion, A. glutinosa and T. distichum species show higher diameter growth in leachate treatment compared with other species, making them suitable plants for contaminated areas. It can be concluded that hydrophilic species have shown a better growth response to different leachate treatments. Due to the higher content of nutrients in compost leachate, it is necessary to investigate the appropriate ratio of compost leachate and water in irrigation treatment. It is, therefore, important to consider different compost leachate concentrations on plant growth and biomass, which can be suggested in future research.