Impaginato 121 1. Introduction Acquisition of mineral nutrients is important to plant growth and productivity. The ability of plants to acquire nutrients may be associated with root colo- nization with arbuscular mycorrhizal fungi (AMF) (Clark and Zeto, 1996). AMF are obligatory biotrophic symbionts occurring in nearly all natural and agricul- tural soils and commonly colonize roots of many plant species (Smith and Read, 1997). Acquisition of mineral nutrients by plants with AMF depends on factors such as soil pH, soil nutrient deficiencies, AMF isolate, and plant species (Sylvia and Williams, 1992). Previous studies showed a positive response of cot- ton to AMF (Liu et al., 1994; DeFeng et al., 1998; Ibrahim, 2010). In subsistence agriculture systems, it is important to use indigenous AMF that are ecotypi- cally adapted to the site (Davies et al., 2005). Native AMF can grow and function better in soils from which they are isolated, e.g. agricultural systems (Calvente et al., 2004). Phosphogypsum (PG) is the main by-product of the industrial production of phosphoric acid by treat- ment of rock phosphate with sulfuric acid. Calcium sulfate is the dominant component in PG. PG con- tains the radioactive materials 226Ra and 210Po, phos- phorus, silicon, Fe, Cu, and F– (Al-Masri et al., 2004). Studies suggest that PG can be used in the improve- ment of soil structure, plant growth and agricultural production (Alcordo and Rechcigl, 1993), enhancing seedling emergence (Vyshpolsky et al., 2010), and increasing available S and P (Al-Oudat et al., 1998). The use of PG as a fertilizer in agriculture has been practiced in many parts of the world (Enamorado et al., 2009) without constituting environmental haz- ards to soil and crop tissue (Al-Oudat et al., 2011). Application of PG (a poorly soluble source of P) to soil may become available to plants by solubilization f r o m A M F ( A l - K a r a k i a n d A l - O m o u s h , 2 0 0 2 ) . Solubilization of PG might insure a continuous supply of P without inhibiting root AMF colonization (Cui et al., 2014). In addition, enhanced acquisition of nutri- Adv. Hort. Sci., 2016 30(3): 121-128 DOI: 10.13128/ahs-20247 Arbuscular mycorrhizal isolate and phosphogypsum effects on growth and nutrients acquisition of cotton (Gossypium hirsutum L.) M. Ibrahim Department of Agriculture, Atomic Energy Commission of Syria, P.O. Box 6091, Damascus, Syria. Key words: Arbuscular mycorrhizal fungi, Gossypium hirsutum, indigenous, phosphogypsum. Abstract: Cotton was grown in pots with added phosphogypsum (PG) to evaluate the effect of indigenous arbuscular mycorrhizal fungi (AMF) and phosphogypsum on cotton growth and acquisition of phosphorus (P), potassium (K), calci- um (Ca), manganese (Mn), iron (Fe), copper (Cu), and zinc (Zn). AMF isolate was a mixture of Glomus intraradices, Glomus viscosum, and Glomus mosseae previously isolated from a cotton field. Shoot dry biomass was enhanced signifi- cantly by both indigenous AMF and PG. Shoot dry biomass and seed cotton yields were enhanced by the AMF and PG combination and even more when PG in compost was added to mycorrhizal plants. P content in AMF with PG and in AMF with PG/compost treated plants was, respectively, 209.3 and 278.7%, significantly higher than control. Acquisition of K, Ca, and micronutrients was significantly enhanced by the combination of AMF and PG. The treatment of AMF with PG/compost induced the highest contents in Mn, Fe, Cu and Zn which were found to be, respectively, 287, 201, 192.8, and 171% higher compared to control. Results indicate that cotton growth responded to indigenous AMF in soils amend- ed with PG. Combination of AMF with PG added in compost can ensure satisfactory benefits for cotton growth in low input, sustainable cropping systems. (*) Corresponding author: ascientific@aec.org.sy Received for publication 21 April 2016 Accepted for publication 1 July 2016 Copyright: © 2016 Author(s). This is an open access article 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. http://creativecommons.org/licenses/by/4.0/ http://creativecommons.org/licenses/by/4.0/ Adv. Hort. Sci., 2016 30(3): 121-128 122 ents by AMF plants in combination with PG has been reported (Al-Karaki and Al-Omoush, 2002; Bai et al., 2011). Compost increases soil organic carbon (El Mrabet et al., 2014) and could increase the release of micronutrients in the soil, making them more avail- able to plants (Habashy et al., 2008; Jan et al., 2014). On the other hand, addition of PG during manure composting decreased the amount of ammonia lost by volatilization (Prochnow et al., 1995). Therefore, addition of compost and the introduction of mycor- rhizal technology may become an effective way of applying PG to soils with P deficiency. The objective of this research was to determine the effects of indigenous AMF, in combination with Syrian PG alone or integrated in compost, on growth and mineral nutrients acquisition of a Syrian cotton variety. 2. Materials and Methods The experiment was conducted in pots during the summer season (May-September 2013) at Der- Al h a j a r res ea rc h S t a t i o n , l o c a t ed s o u t h ea s t o f Damascus, Syria (33°21’ N, 36°28’ E) at 617 m above sea level. The area is located within an arid region in which the total annual precipitation is 120 mm. Sandy clay loam soil was air dried, sieved to pass a 3 mm screen, and pasteurized at 5 kGy of gamma ray (GR) with 60Co source using a gamma irradiator (ROBO, Russa). Phosphogypsum (PG) was previously collected from the area near the phosphoric acid factory in Homs (180 km N of Damascus). A total of 20 compos- ite samples of PG were obtained from the levels cor- responding to pile ages of approximately 1, 3-6 and 7-12 years, from the top, middle and bottom layers, respectively (each sample weighed 1 kg). PG samples were ground, homogenized, and sieving through a 0.5 mm sieve. Before planting, soil was mixed with PG alone (at a rate of 30 g kg-1 dry soil) and PG inte- grated in compost (PG/compost mixture was pre- pared to be applied at a rate of 30 g of compost plus 30 g of PG per kg dry soil). Compost was pasteurized at 120°C for 20 min in the autoclave. Apart from PG, no chemical fertilizers were added during the experi- ment. Mycorrhizal inoculum was a mixture of Glomus intraradices (Schenck & Smith), Glomus viscosum (Nicolson), and Glomus mosseae (Nicol. & Gerd.) Gerd. & Trappe. AMF inoculum was previously isolat- ed (Ibrahim, 2010) from a cotton field at Der-Alhajar Research Station and multiplied in pot cultures using onion (Allium cepa) as a host. The inoculum consisted of fragments of onion root and spores mixed with soil. Half of the pots were inoculated with AMF inocu- lum (100 g per pot) at the time of sowing. Non- mycorrhizal pots were prepared by mixing the same amount of sterilized AMF inoculums. The treatments were: T1, no AMF inoculation without PG; T2, AMF inoculation without PG; T3, no AMF inoculation with PG; T4, AMF inoculation with PG; T5, no AMF inoculation with PG/compost; and T6, AMF inoculation with PG/compost. Seeds of cotton (Gossypium hirsutum cv. Aleppo 33/1) were sterilized in 20% NaClO for 1 min and sub- sequently rinsed with sterilized water. They were then sown five per pot and placed to grow under nat- ural conditions. Ten days after emergence, seedlings were thinned to one per pot; the roots of discarded plants were left in the soil to avoid removing the AMF inoculum. Plants were watered with tap water as needed. Growth parameters, such as plant height and fresh weight, were measured at the physiological maturity stage. The total shoot dry weights were measured after oven drying to constant weight at 70°C. Boll weight and number of mature bolls per plant at the first handpicking were recorded. The seed cotton yield and percent lint of each plant was determined at one handpicking for all treatments. The vegetative portion of the plants was ground to a fine powder (0.5 mm). Nitrogen was determined using the Kjeldahl method and phosphorus was determined colorimetrically using a spectrophotome- ter (Thermo Spectronic, UK), while determination of Ca, K, Fe, Zn, Cu, Mn was performed by x-ray fluores- cence (XRF). Root samples were rinsed free of soil, cut into 1 cm fragments, thoroughly mixed, cleared with KOH and stained with acid fuchsin in lactoglyc- erol. Percent root colonization and percent root length colonized by AMF were determined micro- s c o p i c a l l y u s i n g a g r i d l i n e i n t e r c e p t m e t h o d (Giovannetti and Mosse, 1980). The experimental design was randomized com- plete blocks with four replications. Data were sub- jected to analysis of variance by the SAS program (SAS Institut Inc, 2004) and means were compared using the Least Significant Difference (LSD) test at a probability level of P≤0.05. Ibrahim - AM isolate and phosphogypsum effects on cotton 123 3. Results Addition of PG to the soil significantly decreased pH (Table 1). AMF root colonization was between 22.8 and 30.8% regardless of PG addition; the per- cent was higher for plants grown without added PG t h a n a d d e d P G a l o n e . A d d i n g P G i n c o m p o s t increased the percent of AMF root colonization of cotton plants (Table 1). The percentage of mycor- rhizal root length was 66.3, 54.5 and 73.3% in the AMF plants, AMF plus PG, and AMF with PG/compost treated plants, respectively (Table 1). No AMF root colonization was noted for plants grown without AMF. Significant differences between mycorrhizal and nonmycorrhizal plants were noted for shoot dry bio- mass regardless of PG addition (Table 1). Shoot dry biomass was significantly enhanced by indigenous AMF and when the mixture of PG/compost was added to soil. Application of PG to soil significantly increased shoot dry biomass for both mycorrhizal and nonmycorrhizal plants. Shoot fresh weight signif- icantly increased in AMF inoculated and PG treated plants in comparison to the control (Table 1). Plant height at harvest was between 38.3 and 73.8 cm, and it was significantly enhanced by AMF inoculation and PG addition compared to control. The maximum plant height was observed for mycorrhizal cotton plants grown with PG/compost mixture. The growth response of cotton plants to AMF, PG, and AMF plus PG treatments increased by 59.6, 49.4, and 76.3% over control, respectively (Table 2). In addition, the growth response of cotton to the com- bination of AMF with PG/compost was higher by 118.9% over control (Table 2). Yield components of cotton under different treat- ments are shown in Table 2. The number of bolls per plant was significantly increased by both AMF and PG in comparison with control. The plants showed the highest number of bolls when PG/compost mixture was added to AMF plants (T6). The increase in boll number led to an increase in seed cotton yield, which was improved by both AMF and PG. Seed cotton yield varied between 50.83 g plant-1 (4574 kg ha-1 on the basis of a density of nine plants m-2) and 18.38 g plant-1 (1654 kg ha-1). The highest seed yield of cotton was observed in AMF plants with added PG/compost. Boll weight was generally higher in AMF plants and PG treated plants than control and it was significantly higher with the AMF plus PG/compost treatment compared to other treatments. Percent lint varied between 47.3 and 34.3%, and AMF inoculation increased it significantly. In addition, lint percentage was significantly increased by PG and this increase was clearly noted when PG was contained in com- post. N and P concentrations in the vegetative portions of plants were significantly affected by AMF inocula- tion (Table 3, Fig. 1). The concentrations of N and P Table 1 - Experimental soil pH, mycorrhizal root colonization, and some growth parameters of cotton plants grown with different treatments of arbuscular mycorrhizal fungi (AMF) and added phosphogypsum (PG) Treatment AMF colonization (%) Mycorrhizal root length (%) Soil pH Plant height (cm) Fresh biomass (g plant-1) Dry biomass (g plant-1) Control 0 0 8.1 a 38.3 e 141.72 c 44.40 e AMF 24.60 b 66.30 b 8.1 a 55.0 d 256.30 ab 70.38 cd PG 0 0 7.5 b 58.0 cd 240.86 b 65.79 d AMF+PG 22.80 bc 54.50 bc 7.5 b 62.0 bc 295.87 a 78.05 b PG/compost 0 0 7.2 c 64.3 b 255.43 ab 72.97 bc AMF+PG/compost 30.80 a 73.30 a 7.1 c 73.8 a 316.52 a 96.64 a Mean values within columns followed by different letters are significantly different at P<0.05. Table 2 - Growth response and some yield components of cot- ton plants grown with different treatments of arbuscu- lar mycorrhizal fungi (AMF) and added phosphogyp- sum (PG) Treatment Growth response (%) Boll number (per plant) Boll weight (g) Seed cotton yield (g plant-1) Lint (%) Control 0 5.3 c 4.9 c 18.4 d 34.3 f AMF 59.6 bc 7.8 b 5.1 b 32.9 c 37.9 e PG 49.4 c 7.3 b 5.2 b 29.8 c 42.3 d AMF+PG 76.3 b 8.3 b 5.3 b 36.9 b 42.9 c PG/compost 64.7 bc 8.0 b 5.5 b 36.5 b 46.4 b AMF+PG/compost 118.9 a 9.5 a 6.1 a 50.8 a 47.3 a Mean values within columns followed by different letters are significantly different at P<0.05. Values are mean (N= 4). Growth response (%)= (DWAMF - DWcontrol) x100/DWcontrol. Lint (%)= (lint weight/seed cotton weight) x 100. Seed cotton= seed + lint. Table 3 - Concentrations of K, Ca, and micronutrients in vegeta- tive portion of cotton plants grown with different treatments of arbuscular mycorrhizal fungi (AMF) and added phosphogypsum (PG) Treatment K (mg g-1 DM) Ca (mg g-1 DM) Mn (µg g-1 DM) Fe (µg g-1 DM) Cu (µg g-1 DM) Zn (µg g-1 DM) Control 22.28 c 30.42 e 85.05 c 593.8 d 3.63 d 15.23 d AMF 28.57 b 33.44 d 127.75 b 676.3 c 4.62 c 18.78 b PG 23.19 c 34.65 d 104.75 bc 688.3 c 3.78 d 16.28 cd AMF+PG 29.44 b 40.28 b 154.75 a 797.5 b 4.69 c 20.58 a PG/compost 29.61 b 36.72 c 116.25 b 766.0 b 5.12 bc 16.68 c AMF+PG/compost 32.67 a 43.61 a 172.75 a 930.8 a 5.59 a 21.88 a Mean values within columns followed by different letters are significantly different at P<0.05. Adv. Hort. Sci., 2016 30(3): 121-128 124 were generally higher for mycorrhizal than for non- mycorrhizal plants. PG significantly increased N con- centration only when combined with compost for nonmycorrhizal (T5) and mycorrhizal plants (T6), while it significantly increased P concentration in nonmycorrhizal and mycorrhizal plants. The role of the combination of AMF and PG in improving plant P content was noted (Table 4). Data indicate that maximum plant P contents of 107.8 and 131.9 mg plant-1 were found in AMF plus PG and AMF with PG/compost treatments, respectively, which was significantly higher (P≤0.05) by 209.3 and 278.7%, respectively, over control (Table 5). The concentrations of K and Ca were significantly higher in the vegetative portion of mycorrhizal com- pared to nonmycorrhizal plants regardless of PG (Table 3). PG significantly increased Ca concentration in nonmycorrhizal and mycorrhizal plants; added alone it had no significant effect on K concentration in either group. The concentrations of both elements increased significantly when PG/compost mixture was added to mycorrhizal plants. Higher concentrations of Mn, Fe, Cu, and Zn were noted for mycorrhizal than for nonmycorrhizal plants (Table 3) and PG significantly increased Fe concentra- tion. Mn and Zn concentrations were increased by PG only in AMF plants while PG had no significant effect Fig. 1 - Concentrations of N and P in vegetative portion of cot- ton plants grown at different treatments (T1= no AMF without PG; T2= AMF without PG; T3= no AMF with PG; T4= AMF with PG; T5= no AMF with PG/compost; and T6= AMF with PG/compost). Table 4 - Contents of nutrients in cotton plants grown with different treatments of arbuscular mycorrhizal fungi (AMF) and added phos- phogypsum (PG) Treatment Nutrient content (mg plant-1) N P K Ca Mn Fe Cu Zn Control 708.0 e 35.2 e 465.3 e 634.0 e 1.77 d 12.5 d 0.08 d 0.32 e AMF 1165.7 c 86.5 c 884.8 c 1036.8 c 3.97 c 21.0 c 0.14 c 0.58 c PG 890.4 d 45.2 d 595.0 d 887.5 d 2.69 d 17.6 c 0.10 d 0.42 d AMF+PG 1331.8 b 107.8 b 1015.0 b 1388.5 b 5.35 b 27.5 b 0.16 c 0.71 b PG/compost 1402.7 b 82.3 c 1013.7 b 1262.0 b 4.02 c 26.5 b 0.18 bc 0.57 c AMF+PG/compost 1627.8 a 131.9 a 1276.5 a 1705.1 a 6.76 a 36.4 a 0.22 a 0.85 a Mean values within columns followed by different letters are significantly different at P<0.05. Table 5 - Percentage change in nutrient contents (NC) due to PG amendment and AMF inoculation of cotton plants Treatment Nutrient content change (%) N P K Ca Mn Fe Cu Zn AMF 65.4 c 148.5 c 91.8 b 65.2 c 128.6 c 73.3 bc 90.6 b 85.0 c PG 25.9 d 30.0 d 28.2 c 40.6 c 56.2 d 44.4 cd 29.3 c 31.8 d AMF+PG 89.1 bc 209.3 b 119.1 b 120.9 b 207.3 b 126.3 b 115.6 b 123.9 b PG/compost 97.7 b 135.6 c 118.5 b 100.0 b 129.2 c 115.3 b 87.4 b 80.4 c AMF+ PG/compost 130.9 a 278.7 a 177.5 a 171.2 a 287.1 a 201.1 a 192.8 a 171.0 a Data in the same column followed by the same letter are not significantly different (P<0.05). Nutrient Content (NC) change=(NCAMF - NCnonAMF)x100/NCnonAMF. Ibrahim - AM isolate and phosphogypsum effects on cotton 125 on Zn and Mn concentration in nonmycorrhizal plants. Also, PG had no significant effect on Cu con- centration in either AMF or non-AMF plants. The highest concentrations of Mn, Fe, Cu, and Zn were observed at AMF plus PG/compost treated plants compared to other treatments. Plant contents of K, Ca, Mn, Fe, Cu, and Zn were significantly higher for mycorrhizal than for nonmyc- orrhizal plants (Table 4). The data revealed that maxi- mum plant uptake of K, Ca, Mn, Fe, Cu, and Zn was found in the treatment of indigenous AMF with PG/compost, which was significantly (P≤0.05) higher by 177.5, 171.2, 287.1, 201.1, 192.8, and 171%, respectively, over control (Table 5). 4. Discussion and Conclusions The soil P concentration in this study was low (3 mg kg-1), and this nutrient normally has to be added to this soil to provide sufficient P for plant growth. Addition of poorly soluble forms of P, such as phos- phogypsum, to soil had no negative effect on AMF root colonization, as was reported by Cui et al. (2014). This may be because AMF root colonization often depends on given amounts of soluble P in the soil at the time of root colonization (Stribley et al., 1980). In particular, greater root infection was found with AMF inoculation plus PG/compost treatment and it was possibly due to the improvement of the rooting zone environment which stimulated better root proliferation (Nagahashi et al., 1996; Van der Heijden and Kuyper, 2001). Soil pH affects the availability of nutrients and how the nutrients react with each other. Application of PG to soil lowered soil pH, a result which is in agreement with literature reports of previous studies (Al-Karaki and Al-Omoush, 2002; Lee et al., 2009). The lower soil pH caused by PG might be attributed to the release of phosphoric acid and sulfuric acid contained in PG. The increase in cotton plant biomass by PG cor- roborates reports by Zhang et al. (2014) who showed that amendment of PG significantly increased shoot biomass in tobacco, regardless of AMF inoculation. According to Quintero et al. (2014), increased dry matter of tomato by PG can be ascribed, at least in part, to an increase in water use efficiency. Greater fresh biomass and plant height of inoculated cotton compared to control was noted in this study, which is in accordance with other earlier studies on cotton (Afek et al., 1991; DeFeng et al., 1998). Enhanced cotton growth with the combination of AMF and PG agrees with previous studies conducted with different plant species such as wheat (Al-Karaki and Al-Omoush, 2002), maize (Bai et al., 2011), tomato (Cui et al., 2014), and shallot (Gu et al., 2012). Improved growth of AMF and PG treated plants may have been due to improved soil P avail- ability. The trend noted for N concentration and bio- mass of AMF plus PG/compost treated plants might be due to the compost releasing its nitrogen gradual- ly to the soil/crop to produce a greater number of leaves. Strong mycorrhizal effects on cotton were also observed when looking at the nutrients uptake. Higher K and Ca in mycorrhizal than in nonmycor- rhizal cotton is supported by Liu et al. (2002) who reported that AMF enhanced acquisition of the nutri- ents that move mainly by mass flow. PG/compost had a positive effect on Ca and K concentration in m y c o r r h i z a l c o t t o n w h i c h c o u l d b e d u e t o a n improvement in soil organic matter and exchange- able Ca and K by compost (Adeleye et al., 2010). El Mrabet et al. (2014) also showed that bio-compost improved soil K-extractable. Increasing P uptake of plants due to AMF inoculation has been widely reported (Deguchi et al. 2007; Sharif et al., 2009; Ibrahim, 2010). In our study, increased P concentra- tion and uptake by PG addition to mycorrhizal cot- ton is supported by Zhang et al. (2015) who reported that PG amendment significantly increased the con- centration and absorption of P in mycorrhizal and nonmycorrhizal tobacco plants. Also, Gu et al. (2012) found that P concentration in shallot was increased by increasing PG, and the combination of PG and AMF colonization can improve P uptake by shallot to different degrees. Our results show that indigenous AMF increased the concentrations of Cu, Zn, Fe, and Mn in cotton; similar results were obtained in cotton inoculated with different species of AMF (Liu et al., 1994; Ibrahim, 2010). Our result regarding enhanced acquisition of P and micronutrients in AMF cotton grown with PG is supported by Al-Karaki and Al- Omoush (2002) in their work on mycorrhizal wheat grown with PG. The extension of AMF hyphae, beyond the root zone, provides P and other nutrients to plants during growth stages. The ability of the hyphae to extend the root system should be especially beneficial in the case of cotton because its roots have a low density per unit soil volume (McMichael, 1990). In this case, Adv. Hort. Sci., 2016 30(3): 121-128 126 AMF likely contributed P (and other mineral nutri- ents) from soil and PG particles with which roots would not make contact. High absorption of Zn, Cu, and Fe may be due to greater P uptake by AMF plants (Clark and Zeto, 1996; Davies et al., 2005). On the other hand, the positive response of cotton to AMF inoculation for nutrient concentration could be due to the effectiveness of the AMF isolate in improving soil properties and nutrient availability. Previous reports showed that improvement of plant growth and nutrients acquisition by the combi- nation of PG and AMF depends on compatibility between plant species, the rate of PG added, and the AMF isolate. Bai et al. (2011) reported that shoot growth of PG treated maize strain (40 g kg-1) was sig- n i f i c a n t l y e n h a n c e d w h e n i n o c u l a t e d w i t h Diversispora spurcum, but was significantly inhibited when inoculated with Glomus aggregatum. Gu et al. (2012) reported that the treatment of PG40 addition with Glomus mosseae inoculation had a significant effect in improving shallot biomass and P, S uptake. According to Zhang et al. (2014), the combination of PG40 and G. aggregatum inoculation had the most desirable effects on tobacco growth. U n d e r t h e c o n d i t i o n s i n t h i s s t u d y , a d d e d PG/compost enhanced P and nutrient concentrations of mycorrhizal plants. Previous reports have shown that PG application induced changes in soil chemical properties (decreased soil pH and enhanced ECe, available P, SO4, exchangeable K, Ca and Mg) (Al- Oudat et al., 1998; Lee et al., 2009). In addition, organic fertilizers and AMF inoculation could improve soil physico-chemical properties (Warnock et al., 2007). AMF colonization enhances soil aggregation by exuding the glycoprotein, glomalin, from extrarad- ical hyphae (Wright and Upadhyaya, 1998). The improved soil structure enhances air and water per- colation, improves root system access to soil water and nutrients, and improves crop production (Celik et al., 2004). Therefore, the increase in nutrients noted in AMF and PG/compost treatments could be due to improved soil structure and to increased release of nutrients in the soil, which become more available to the plant (Habashy et al., 2008; Jan et al., 2014). Enhanced acquisition of nutrients and plant growth by AMF and PG was reflected by increased yield and yield components of cotton. Previous stud- ies showed that PG increased grain yield of barley, wheat, and cotton (Al-Oudat et al., 2011). Cui et al. (2014) reported that tomato yield of AMF or AMF plus PG seedlings were significantly higher than those of the non-mycorrhizal seedlings. Al-Karaki and Al- Omoush (2002) reported that grain yield of wheat was enhanced by PG, and even more so when roots were colonized with AMF. Cotton inoculation with indigenous arbuscular mycorrhizal fungi (AMF) and soil amendment with phosphogypsum (PG) enhanced nutrients acquisition from soil and improved growth and yield of cotton. However, mycorrhizal plants grown with PG and compost mixture had greater growth and yield than plants grown with PG alone. Therefore, the combina- tion of AMF with PG added in compost can ensure satisfactory benefits for cotton growth and yield in low input, sustainable cropping systems. Acknowledgements The author would like to thank the Atomic Energy Commission of Syria for encouragement and techni- cal support. 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