35 1. Introduction Pepino (Solanum muricatum Ait.), a little-known her- baceous subshrub Solanaceous plant, is native of the tropi- cal and subtropical Andes in South America. It is culti- vated for its edible juicy, scented and sweet fruits (Prohens et al., 1996) and has been introduced to different countries, becoming a specialty fruit (Ahumada and Cantwell, 1996). Today, pepino is a species of increasing economic inter- est and it has considerable potential for future exploita- tion (Prohens et al., 1996). The cultural techniques used in modern tomato growing have been adapted with slight modification to pepino management (Dennis et al., 1985). Symbiotic associations between arbuscular mycorrhi- zal fungi (AMF) and plant roots in the natural environment provide a range of benefits to the host plant, however many conventional agricultural practices are detrimental to AMF (Gosling et al., 2006). Organic farming systems may be less detrimental to AMF, because they exclude the use of chemical fertilizers and most biocides and generally have diverse rotations. Organic matter influences the nutrient profile, soil struc- ture, water holding capacity and pH, all of which directly and or indirectly influence AMF development (Bagyaraj, 1991). Addition of organic amendments to soil has been reported to enhance plant biomass, mycorrhizal infectivity, and proliferation of AM fungal hyphae in soil (Joner and Ja- kobsen, 1995; Dai et al., 2011). Vermicompost as an organic fertilizer provides some essential nutrients for supporting plant growth compared with chemical fertilizers. To the best of our knowledge, there is no published re- port about the association of pepino with AMF in litera- ture. The objectives of the present study were to determine: 1) the association level of two AMF species with pepino plant; 2) the possible beneficial effects of symbiosis on plant physiology and fruit quality; and 3) the benefits of vermicompost on AMF association with pepino. 2. Materials and Methods Pepino (cv. Kanseola) mother plants were obtained from Mashad Ferdowsi University research station, Iran. Cuttings with an average 20 cm length and four buds were rooted in a 1:1 (v:v) peat and sand mixture for four weeks. General cultural practices were according to Lopez et al. (2000). Influence of arbuscular mycorrhizal fungi on physiology and fruit quality of Pepino (Solanum muricatum Ait.) in vermicompost amended medium J. Javanmardi* (1), M. Zarei**, M. Saei* * Department of Horticulture, College of Agriculture, Shiraz University, Shiraz, Iran. ** Department of Soil Sciences, College of Agriculture, Shiraz University, Shiraz, Iran. Key words: fruit quality characteristics, mycorrhizal symbiosis, organic fertilizer, pepino. Abstract: The association level of pepino (Solanum muricatum Ait.) with two arbuscular mycorrhizal fungi (AMF) species (Glomus etunicatum and G. versiforme) was evaluated for the first time. The first part of experiment showed 30 and 50% root colonization for the two AMF species, respectively, while the second part of study was a pot experiment under green- house conditions. The effects of vermicompost and root inoculation with G. etunicatum and G. versiforme on reproductive stage, yield and fruit quality of pepino were investigated. Treatments included two levels of vermicompost (0 and 20% v/v) and inoculation with the two fungi species along with a non inoculated control. Application of vermicompost increased the number of flowers, fruits and fruit weight, but decreased the number of days from plant setting to first flower and fruit set, fruit dry matter percent, fruit titratable acidity and vitamin C content. Inoculation with G. versiforme increased fruit dry matter percent, fruit titratable acidity and fruit vitamin C content compared with the non inoculated control (NIC) plants. Plants inoculated with G. etunicatum showed greater fruit weight and juice pH compared to NIC plants. AMF inoculation in vermicompost amended pots led to 14 and 10 days earlier flowering for G. versiforme and G. etunicatum, respectively compared to those not amended with vermicompost. G. etunicatum in vermicompost supplemented medium hastened fruit set by 5.5 days compared to those without vermicompost application. Fruit quality characteristics were affected differently for the two AMF-inoculated plants in presence of vermicompost. Adv. Hort. Sci., 2014 28(1): 35-42 (1) Corresponding author: javanm@shirazu.ac.ir Received for publication 12 April 2014 Accepted for publication 30 May 2014 36 AMF inocula AMF spores were obtained from the Department of Soil Science, Faculty of Agriculture, Shiraz University, Iran. Glomus versiforme was isolated from a non-con- taminated area of Anguran Mine, Zanjan, Iran (Zarei et al., 2008) and G. etunicatum was provided from Tabriz University, Iran; these fungi are abundant in Iranian soils (Aliasgharzadeh et al., 2001; Kariman et al., 2005). My- corrhizal inocula were prepared through the trap culture of maize (Zea mays L.) on culture medium composed of autoclaved soil/quartz-sand (<1 mm) (1:4, v/v). Si- multaneously, some pots containing non autoclaved soil were kept without any spore inoculation to preserve the naturally-occurring microbial association and used for non-inoculated control (NIC) treatments. After four and a half months, at the beginning of the maize reproduc- tive period, shoots were removed and the contents of pots (mycorrhizal roots plus soil possessing fungal spores and mycelia) were maintained in polyethylene bags at 4°C. The potential of inoculants (spore numbers of 10-12 g-1 substrate and root colonization of 80-85%) for spore extraction, number, and evaluation of root colonization were measured based on the method described by Zarei et al. (2008). Examination of arbuscular mycorrhizal symbiosis The association level of pepino plant with two AMF species along with a NIC was evaluated in a completely randomized design with three replications. The presence of AM propagules and the percentage of root coloniza- tion was determined after eight weeks of inoculation. The grid-line intersect method was used after cleaning washed roots in 10% KOH and staining with 0.01% fuchsin acid in lactoglycerol according to the method described by Kormanik and McGraw (1982). The AMF species colonizing roots of pepino plants were used for the main experiment. Main experiment The experiment was carried out in a polyethylene greenhouse using 10 L pots. The experimental design was 2×3 factorial with four replications (four plants each) in a completely randomized arrangement. The first factor consisted of control (V 0 : no vermicompost) and V 1 : vermicompost application at 20% (v/v) to soil. The second factor was soil inoculation with G. etunicatum and G. versiforme. Non-inoculated pots were considered as control (NIC). Four-week-old rooted cuttings were planted in pots which contained the described media for treatments. The physical and chemical properties of soil and vermicompost are presented in Table 1. For the mycorrhizal treatments 50 g of each AMF in- oculum was used as a thin layer near the roots of cut- tings. NIC treatments consisted of adding 50 g of media from control maize trap culture pots (contained non- autoclaved soil with no spore inoculation) as described earlier (see section 2.1). Pots containing pepino plants were arranged in rows, 1 m apart and 0.4 m between pots. Plants were trained into three main branches. A to- tal amount of 35 g·m-2 of organic soluble fertilizer Bio- min464-sp (JH Biotech, Inc. Ventura, CA) was applied to fertigated plants during the experimental period. Irriga- tion frequency from transplanting to harvest varied from 2 to 4 days with 0.4 - 1 L per irrigation based on plant requirements. Plant reproductive phase measurements To evaluate the effects of colonization with AMF and vermicompost application on the pepino reproductive stage, the following characteristics were assayed: number of days to first flower formation, number of flowers in the first and second truss, number of days from transplanting to first fruit formation, fruit number and fruit set percent- age, and fruit fresh weight. Fruit quality factors including vitamin C content at maturity [using the method described by Association of Official Agricultural Chemists (AOAC, 1984)], titratable acidity (Gutiérrez-Miceli et al., 2007), fruit juice acidity (using pH meter), soluble solid content (using refractometer), and dry matter percent were as- sayed after harvest. Statistical analyses The experiment was arranged in a completely ran- domized design. Four replicates per treatment were used, each with four plants. Data were analyzed using JMP sta- tistical software, version 5.1 (SAS Institute Inc., Cary, NC, USA). If the interaction was significant, it was used to explain results; if it was not significant, means were separated with Least Significant Differences (LSD) test at P≤0.05. 3. Results and Discussions The ANOVA revealed significant main and interac- tion effects of vermicompost and AMF for most measured characteristics (Table 2). Determination of plant association with AMF For the first time in literature, our results report the as- sociation of pepino with two AMF. The results indicate that G. etunicatum and G. versiforme can colonize pepino Table 1 - Physical and chemical properties of soil and vermicompost used for the experiment Sand (%) Silt (%) Clay (%) EC (dS/m) pH N (%) P K Soil 34 46 20 1.63 7.82 0.031 5.4 mg/kg 135 mg/kg Vermicompost - - - 5 8.25 1.45 1.75% 1.2% 37 roots up to 30 and 50 percent, respectively. It has been stated that the difference between root colonization per- centages of Glomus strains might be due to the fact that AMF have a wide host range, yet certain combinations of hosts and fungi are more efficient than others for either the fungus or the host (Douds and Millner, 1999; Gutierrez- Miceli et al., 2008). van der Heijden et al. (1998) showed that plant species differed in their dependency on AMF. Some results suggest that AMF has some degree of host- specificity (Eom et al., 2000). Root colonization The main and interaction effects of vermicompost and AMF on root colonization percent were significant (Table 2). Root colonization percentages in vermicompost amend- ed soils were about 25% greater than the V 0 treatment regardless of AMF (Table 3). The greater percentage of mycorrhization in vermicompost amended soils has been attributed to the humic substances found in vermicompost, resulting in an increased metabolism of soil microorgan- isms, and the nutrient uptake (Atiyeh et al., 2002). There was no significant difference between colonized root length of G. versiforme and G. etunicatum in ver- micompost amended soils, but compared to NIC plants, a greater root colonization was observed (2.46 and 2.80 times, respectively) (Table 4). Mycorrhizal plants colo- nized well with introduced AMF species. A 15% mean root colonization in NIC plants shows that the soil used contained native AMF populations. More than 100% greater root colonization was ob- served in the presence of vermicompost when compared with V 0 treatment (Table 5). This could be due to greater organic matter available for growth and development of AMF hyphae; it has been reported that AMF mycelia can mineralize and enhance utilization of organic materials (Feng et al., 2003). Days to first flower formation The main and interaction effects of vermicompost and AMF on the number of days to first flower formation were significant (Table 2). The number of days from planting to first flower formation was much lower in pots amended with vermicompost than in V 0 treatments (Table 3). Previ- ous studies showing earlier flowering due to vermicom- post application on German chamomile, begonia, and coleus (Tomati et al., 1983; Tomati et al., 1987; Azizi et al., 2008) are in agreement with our results. The reason for this has been attributed to the development of efficient photosynthetic structure, higher dry matter production, early initiation, and greater development of the reproduc- tive system (Krishna et al., 2008). Inoculation with G. etunicatum gave earlier flowering than G. versiforme-inoculated plants (Table 4). In agree- ment with our results, Chrysanthemum cuttings inoculated with AMF had a significantly shorter flowering time com- pared with non-inoculated plants (Sohn et al., 2003). It is reported that in AMF-inoculated tomato plants, the time between emergence and completion of fruit set (the du- ration of purely vegetative growth) decreased, while the duration of the reproduction period increased (Bryla and Koide, 1998). This is consistent with the idea that plant resource status serves as a partial control of the switch Table 2 - Analyses of variance for vermicompost application and arbuscular mycorrhizal fungi inoculation on some pepino plant characteristics Source of variation df Mean squares Root colonization Days to first flower Flower number in truss Days from flowering to fruit set Fruit Number Fruit fresh weight Fruit dry matter percent Fruit juice pH Fruit titratable acidity Total soluble solids Fruit vitamin C content Vermicompost 1 67** 1056.25** 28.44** 42.25** 27.39** 2321.47** 14.06** 0.06 ns 0.15** 0.13 ns 264.23** AMF 2 26** 44.62** 0.16 ns 45.42** 4.64 ns 513.87* 90.97** 0.08** 0.21** 2.98 ns 165.20** Vermicompost × AMF 2 12* 32.92 ** 0.75 ns 28.15** 4.99 ns 18.16 ns 28.72** 0.11** 0.12** 5.92* 147.53** Error 30 0.004 5.08 0.87 1.58 3.46 130.21 0.58 0.02 0.01 1.00 1.56 Total 35 ns, *, *= non-significant, significant at 0.05 and 0.01, respectively. Table 3 - The main effects of vermicompost application on some pepino plant characteristics Treatment Root colonization percent Days to first flower Flower number in truss Days from flowering to fruit set Fruit Number Fruit weight (g) Fruit dry matter percent Fruit titratable acidity (ml/100 ml) Fruit vitamin C (mg/100 ml) Control 18 b 74.11 a 7.36 b 16.14 a 1.81 b 29.69 b 11.10 a 0.78 a 19.83 a Vermicompost added 45 a 63.28 b 9.14 a 13.97 b 3.56 a 45.75 a 9.85 b 0.65 b 14.41 b LSD value at p≤0.05 0.04 1.53 0.63 0.70 1.07 7.77 0.52 0.07 0.85 Values in each column with the same letter are not significantly different using LSD test at p≤0.05. 38 from vegetative to reproductive growth (Marschner, 1995). In mycorrhizal plants, greater root development leads to more phosphorus in vegetative and reproductive tissues, which eventually leads to early flowering (Bryla and Koide, 1998). This might explain the early flowering in this experiment due to inoculation with G. etunicatum. Plants inoculated with G. versiforme and G. etunicatum in vermicompost amended pots had 15 and 10 days earlier flowering, respectively, compared to non vermicompost amended pots (Table 5). The organic material provided by vermicompost can improve growth and development of AMF inoculum (Bending et al., 2004), which enhances nutrient uptake by the plant and hastens plant growth and development (Mahmood and Rizvi, 2010). Flower number in truss A 24% increase in the number of flowers per truss was observed in vermicompost amended pots compared with V 0 treatments, however the effects of AMF and co- application of AMF and vermicompost were not signifi- cant (Tables 2, 3). Previously, a 40% increase in flower number in strawberry was related to the increase in plant biological activity due to a vermicompost application rate of over 10 t/ha (Arancon et al., 2004 b). A 20% (v/v) ver- micompost application in the present study led to a very significant increase in flower number in trusses (Table 2). Some possible factors that improve flowering after vermi- compost application have been attributed to the improve- ment in physical structure of growth medium, increased biological enzymatic activities, increased populations of beneficial microorganisms, or the presence of biologically active plant growth-influencing substances (plant growth regulators) in the vermicompost (Arancon et al., 2008). Our results on increased flower number due to vermicom- post are in agreement with previous reports on eggplant and tomato (Gajalakshmi and Abbasi, 2002). Days to first fruit set The main and interaction effects of vermicompost and AMF on the number of days from flowering to first fruit set were significant (Table 2). Vermicompost amended pots showed fruit set occurring an average of 2.17 days earlier compared with V 0 treatments (Table 3). Non-inoc- ulated control plants and plants inoculated with G. ver- siforme showed fruit set to be three days earlier than in plants inoculated with G. etunicatum (Table 4). The two AMF species showed different interactions with regard to the presence of vermicompost in the me- dium. Those inoculated with G. etunicatum in the pres- ence of vermicompost set fruit 5.58 days earlier compared to non vermicompost amended soil (Table 5). It seems that the potential efficiency of G. etunicatum for earlier pepino fruit set is greater in the presence of vermicompost than with G. versiforme. NIC plants and plants inoculated with G. versiforme with vermicompost added and non vermi- compost added media showed no differences. Fruit number Our results show that vermicompost application was the primary contributing factor in increasing pepino fruit Table 4 - The main effects of arbuscular mycorrhizal fungi inoculation on some pepino plant characteristics Treatment Root colonization percent Days to first flower Days from flowering to fruit set Fruit weight (g) Fruit dry matter percent Fruit juice pH Fruit titratable acidity (ml/100 ml) Fruit Vitamin C (mg/100 ml) NIC 15 b 68.08 ab 13.75 b 32.64 b 8.79 b 5.02 b 0.67 b 16.54 b Glomus versiforme 37 a 70.85 a 14.12 b 35.41 b 13.65 a 4.99 b 0.87 a 21.08 a Glomus etunicatum 42 a 67.15 b 17.29 a 45.10 a 8.98 b 5.15 a 0.62 b 13.73 c LSD value at p≤0.05 5.01 1.88 0.86 9.51 0.63 0.12 0.08 1.04 NIC= Non inoculated control. Values in each column with the same letter are not significantly different using LSD test at p≤0.05. Table 5 - The interaction effects of vermicompost application and arbuscular mycorrhizal fungi inoculation on some pepino plant characteristics Root colonization percent Days to first flower Days from flowering to fruit set Fruit dry matter percent Fruit juice pH Fruit titratable acidity (ml/100 ml) Total soluble solids (brix) Vitamin C (mg/100 ml) No-vermicompost added Non mycorrhizal control 5 c 72.17 b 13.58 b 8.06 d 5.09 ab 0.68 b 7.13 c 22.39 b Glomus versiforme 22 b 78.12 a 14.75 b 15.96 a 4.88 c 1.04 a 9.38 a 24.42 a Glomus etunicatum 27 b 72.04 b 20.08 a 9.28 c 5.06 ab 0.61 b 7.68 bc 12.66 e Vermicompost added Non mycorrhizal control 25 b 64.00 c 13.92 b 9.53 c 4.95 bc 0.65 b 8.15 bc 10.68 f Glomus versiforme 53 a 63.58 c 13.50 b 11.35 b 5.10 ab 0.69 b 7.88 bc 17.74 c Glomus etunicatum 58 a 62.25 c 14.50 b 8.68 cd 5.23 a 0.61 b 8.52 ab 14.80 d LSD value at p≤0.05 7.0 2.66 1.21 0.90 0.17 0.12 1.18 1.47 Values in each column with the same letter are not significantly different using LSD test at p≤0.05 39 number (Table 2). Fruit number in vermicompost amended soils (an average of 3.56) was about 96% greater than V 0 treatments (1.81 fruits) (Table 3). Previously, increased yields of strawberry (Arancon et al., 2004 b) and pepper (Arancon et al., 2005) in vermicompost amended soils in field conditions were attributed to increased fruit number due to the availability of plant growth regulators and humic acids, which produced by the greatly increased microbial populations resulting from earthworm activity (Arancon et al., 2004 a; b). According to our results, the simultaneous increased flower number and fruit set percentage consider- ably increased total yield. Fruit fresh weight The main effects of vermicompost and AMF on fruit fresh weight showed significant differences, but the inter- action of vermicompost and AMF was not significant (Ta- ble 2). Comparing fruit weight in vermicompost amended soils with V 0 treatments showed a 54% increase (Table 3). This result is in agreement with previous studies on the application of vermicompost for eggplant (Moraditochaee et al., 2011), greenhouse pepper (Arancon et al., 2004 a), and tomato (Arancon et al., 2003). It has been stated that the great microbial activity and populations in vermicom- post are probably responsible for a considerable buildup of microbial populations and activity in soils. These improve the soil structure and have an indirect influence on root environment, nutrient absorption, plant growth (Arancon et al., 2005), and yield (Goswami et al., 2001). No significant differences were found between plants inoculated with G. versiforme and NIC treatments. Plants inoculated with G. etunicatum produced fruits with an av- erage weight of 45.1 g, which was about 32% greater than NIC and G. versiforme-treated plants (Table 4). It has been reported that individual tomato fruit weight significantly increased when the plants were colonized with AMF (Bry- la and Koide, 1998). Such evidence, which is in agreement with our results, also showed different increased levels of fruit fresh weight for other inoculated Solanaceous plants, i.e. tomato plants inoculated with G. mosseae (Abdel Latef and Chaoxing, 2010), chili pepper plants inoculated with G. intraradices (Castillo et al., 2009), chileancho pep- per inoculated with G. fasciculatum (Mena-Violante et al., 2006), and non-Solanaceous cucumber (Trimble and Knowles, 1995). Increased yields have been attributed to the increased yield components due to the positive effects of mycorrhiza including facilitated water and nutrient up- take through extension of root surfaces and increased pho- tosynthesis (Ortas et al., 1996; Raman and Mahadevan, 1996; Tarkalson et al., 1998). Fruit dry matter percent The main and interaction effects of vermicompost and AMF on fruit dry matter percent showed significant differ- ences (Table 2). The V 0 treatments produced 12% greater fruit dry matter than pots amended with vermicompost, regardless of AMF inoculation (Table 3). Results of fruit fresh weight and fruit dry matter percentage showed that vermicompost improved water uptake and partitioning in fruits, which had greater fresh weight (due to vermicom- post) and lower dry matter percentages (Table 3). Inoculating pepino plants with G. versiforme increased the fruit dry matter percent to over 50% compared to those inoculated with G. etunicatum and plants not inoculated with AMF (Table 4). The differences could be related to the developmental pattern of AMF species. An increased fruit dry matter percentage in AMF plants has been attrib- uted to improved water and nutrient uptake/translocation, higher photosynthesis (Vamerali et al., 2003), and also to the pattern of dry matter distribution in inoculated plants, which pointed to a role of AMF in carbon partitioning (Mena-Violante et al., 2006). Co-application of vermicompost and AMF showed dif- ferent patterns for fruit dry matter percentage. G. versi- forme in V 0 treatment produced about 40% greater fruit dry matter than vermicompost amended media, but no dif- ferences were observed between vermicompost and non vermicompost amended soils inoculated with G. etunica- tum (Table 5). Fruit juice pH With regard to fruit juice pH, the main effects of AMF and its interaction with vermicompost were highly signifi- cant (Table 2). The pH of pepino plants inoculated with G. etunicatum was 0.13 higher than in NIC plants. The dif- ference between G. versiforme inoculated plants and NIC plants was not significant for fruit juice pH (Table 4). Pre- viously, inoculation of cucumber plants with G. intrara- dices gave no changes in fruit pH (Rouphael et al., 2010). Plants inoculated with G. etunicatum exhibited a high- er fruit juice pH than G. versiforme inoculated plants in V 0 treatment, but the difference was not significant when vermicompost was used (Table 5). Fruit titratable acidity The main and interaction effects of vermicompost and inoculation with AMF showed significant differences with NIC plants for fruit juice titratable acidity (Table 2). The plants grown in vermicompost amended soils (0.65 ml/100 ml fruit juice) had a 20% decrease in titratable acidity compared with plants in non-amended soils (0.78 ml/100 ml fruit juice) (Table 3). In other studies, the effect of ver- micompost on tomato fruit titratable acidity did not show significant differences (Gutiérrez-Miceli et al., 2007). The effect of inoculation of plants with G. versiforme showed a 40% increase in fruit titratable acidity compared with G. etunicatum inoculated plants and the control (Ta- ble 4). Our result is in agreement with a previous paper that reports a significant increase in fruit titratable acidity of AMF inoculated tomato plants (Regvar et al., 2003). A different reaction to vermicompost application was observed for inoculated plants with two different AMFs (Table 5). Fruits of plants inoculated with G. versiforme in the V 0 treatment had a 0.5ml/100ml greater titratable acidity than fruits from G. etunicatum-inoculated plants. 40 It seems that the effect of AMF on pepino fruit juice titrat- able acidity is AMF-species dependent. Total soluble solids The main effects of vermicompost and AMF on total soluble solids were not significant but the interaction was significant (Table 2). Fruits of G. versiforme-inoculated plants in the V 0 treatment had 1.5 Brix greater soluble solid content than those grown in vermicompost amended media. The differences between AMF-inoculated and NIC plants in vermicompost amended treatments were not significant (Table 5). Greater fruit total soluble solids in AMF inocu- lated tomato plants, compared to non-inoculated plants, has been previously reported (Subramanian et al., 2006). Dif- ferent microorganisms have been reported as involved in breaking down (mineralize) and releasing mineral nutrients of organic materials, to then be taken up by plant roots (Lin- derman and Davis, 2004). It seems that G. etunicatum has the ability to improve vermicompost utilization by pepino plant roots, which leads to more efficient photosynthetic ac- tivity and therefore greater total soluble solids in fruits. Fruit vitamin C The main and interaction effects of vermicompost and inoculation with AMF showed significant differences for fruit vitamin C content (Table 2). Fruits produced in ver- micompost amended soils had 37% less vitamin C than fruits in the V 0 treatments (Table 3). This could be related to a 1.5 times greater fresh fruit weight with constant vita- min C content in a unit volume. It seems that the level of vitamin C in pepino fruits is not affected by vermicompost application. Different reports are available on the effect of vermicompost application on fruit ascorbic acid content: some show increased fruit vitamin C in tomato (Sable et al., 2007), while others report no significant effect (Rob- erts et al., 2007). The fruit vitamin C content was 53 and 27% greater in fruits from plants inoculated with G. versiforme as com- pared to fruits from plants inoculated with G. etunicatum and non mycorrhizal treatments, respectively (Table 3). Higher quantities of ascorbic acid in AMF-inoculated to- mato plants compared to non-inoculated plants has been previously reported (Subramanian et al., 2006). The AMF used in this experiment showed different reac- tions to vermicompost application. Fruits from the V 0 treat- ment inoculated with G. versiforme and those inoculated with G. etunicatum in vermicompost amended soils had greater vitamin C than other treatments (Table 5). It seems that the effect of AMF on pepino fruit vitamin C is species dependent. Those plants treated with G. etunicatum had higher vitamin C content when vermicompost was applied, while the same trend was not observed when vermicompost was applied to G. versiforme-inoculated plants. 4. Conclusions Despite the influence of AMF on crop yield as docu- mented in many reports on Solanaceous plants, little is known about the potential of AMF to improve their fruit quality. Crop species and cultivars of plant species can differ dramatically in their ability to respond to different AMF strains. This can complicate predictions of the extent to which AMF colonize roots and the resulting effects on plant growth and development. This is the first report on the effects of AMF inoculation in pepino, on the level of colonization, plant growth, development, and fruit yield and quality. We have clearly demonstrated the positive im- pact of AMF on pepino fruit quality in terms of vitamin C, total acidity, pH, total soluble solid content, increased titratable acidity and dry matter percentage. References ABDEL LATEF A.A.H., CHAOXING H., 2010 - Effect of ar- buscular mycorrhizal fungi on growth, mineral nutrition, antioxidant enzymes activity and fruit yield of tomato grown under salinity stress. - Sci. Hortic., 127: 228-233. AHUMADA M., CANTWELL M., 1996 - Postharvest stud- ies on pepino dulce (Solanum muricatum Ait.): maturity at harvest and storage behavior. - Postharvest Biol. Tech., 7: 129-136. ALIASGHARZADEH N., RASTIN S.N., TOWFIGHI H., ALIZADEH A., 2001 - Occurrence of arbuscular mycorrhi- zal fungi in saline soils of the Tabriz Plain of Iran in relation to some physical and chemical properties of soil. - Mycor- rhiza, 11: 119-122. AOAC, 1984 - Official methods of analysis. 14th ed. - Asso- ciation of Official Agricultural Chemists, Washington, DC, USA. ARANCON N.Q., EDWARDS C.A., ATIYEH R., METZGER J.D., 2004 a - Effects of vermicomposts produced from food waste on the growth and yields of greenhouse peppers. - Bio- resource Technol., 93: 139-144. ARANCON N.Q., EDWARDS C.A., BABENKO A., CAN- NON J., GALVIS P., METZGER J.D., 2008 - Influences of vermicomposts, produced by earthworms and microorgan- isms from cattle manure, food waste and paper waste, on the germination, growth and flowering of petunias in the green- house. - Appl. Soil Ecol., 39: 91-99. ARANCON N.Q., EDWARDS C.A., BIERMAN P., METZGER J.D., LEE S., WELCH C., 2003 - Effects of vermicomposts on growth and marketable fruits of field-grown tomatoes, peppers and strawberries. - Pedobiologia, 47: 731-735. ARANCON N.Q., EDWARDS C.A., BIERMAN P., METZGER J.D., LUCHT C., 2005 - Effects of vermicomposts produced from cattle manure, food waste and paper waste on the growth and yield of peppers in the field. - Pedobiologia, 49: 297-306. ARANCON N.Q., EDWARDS C.A., BIERMAN P., WELCH C., METZGER J.D., 2004 b - Influences of vermicomposts on field strawberries: 1. Effects on growth and yields. - Bio- resource Technol., 93: 145-153. ATIYEH R.M., LEE S., EDWARDS C.A., ARANCON N.Q., METZGER J.D., 2002 - The influence of humic acids de- rived from earthworm-processed organic wastes on plant growth. - Bioresource Technol., 84: 7-14. 41 AZIZI M., REZWANEE F., HASSANZADEH-KHAYYAT M., LACKZIAN A., 2008 - The effect of different levels of ver- micompost and irrigation on morphological properties and essential oil content of German chamomile (Matricaria recu- tita) cv. Goral. - Planta Medica, 74: PE3. BAGYARAJ D.J., 1991 - Ecology of vesicular arbuscular mycor- rhizae, pp. 3-34. - In: ARORA D., B. RAI, K.G. MUKERJI, and G.R. KNUDSEN (eds.) Handbook of applied mycology. Marcel Dekker Inc., New York, Basel, Hong Kong, pp. 720. BENDING G.D., TURNER M.K., RAYNS F., MARX M.-C., WOOD M., 2004 - Microbial and biochemical soil quality indicators and their potential for differentiating areas under contrasting agricultural management regimes. - Soil Biol. Biochem., 36: 1785-1792. BRYLA D.R., KOIDE R.T., 1998 - Mycorrhizal response of two tomato genotypes relates to their ability to acquire and uti- lize phosphorus. - Ann. Bot., 82: 849-857. CASTILLO R.C., SOTOMAYOR S.L., ORTIZ O.C., LEONEL- LI C.G., BORIE B.F., RUBIO H.R., 2009 - Effect of arbus- cular mycorrhizal fungi on an ecological crop of chili pep- pers (Capsicum annuum L.). - Chil. J. Agric. Res., 69: 79-87. DAI O., SINGH R.K., NIMASOW G., 2011 - Effect of arbus- cular mycorrhizal (AM) inoculation on growth of Chili plant in organic manure amended soil. - African Journal of Micro- biol. Res., 5: 5004-5012. DENNIS D.J., BURGE G.K., LILL R., 1985 - Pepinos: cultural techniques. - Information Services, Ministry of Agriculture, Wellington, New Zealand, pp. 2. DOUDS D.D., MILLNER P.D., 1999 - Biodiversity of arbus- cular mycorrhizal fungi in agroecosystems. - Agr. Ecosys. Environ., 74: 77-93. EOM A.-H., HARTNETT D.C., WILSON G.W., 2000 - Host plant species effects on arbuscular mycorrhizal fungal com- munities in tallgrass prairie. - Oecologia, 122: 435-444. FENG G., SONG Y., LI X., CHRISTIE P., 2003 - Contribution of arbuscular mycorrhizal fungi to utilization of organic sources of phosphorus by red clover in a calcareous soil. - Appl. Soil Ecol., 22: 139-148. GAJALAKSHMI S., ABBASI S.A., 2002 - Effect of the applica- tion of water hyacinth compost/vermicompost on the growth and flowering of Crossandra undulaefolia, and on several vegetables. - Bioresource Technol., 85: 197-199. GOSLING P., HODGE A., GOODLASS G., BENDING G.D., 2006 - Arbuscular mycorrhizal fungi and organic farming. - Agr. Ecosys. Environ., 113: 17-35. GOSWAMI B., KALITA M.C., TALUKDAR S., 2001 - Biocon- version of municipal solid waste through vermicomposting. - Asian J. Microbiol. Biotech. Environ. Sci., 3: 205-207. GUTIÉRREZ-MICELI F.A., MOGUEL-ZAMUDIO B., ABUD- ARCHILA M., GUTIÉRREZ-OLIVA V., DENDOOVEN L., 2008 - Sheep manure vermicompost supplemented with a na- tive diazotrophic bacteria and mycorrhizas for maize culti- vation. - Bioresource Technol., 99(15): 7020-7026. GUTIÉRREZ-MICELI F.A., SANTIAGO-BORRAZ J., MON- TES MOLINA J.A., NAFATE C.C., ABUD-ARCHILA M., OLIVA LLAVEN M.A., RINCÓN-ROSALES R., DEN- DOOVEN L., 2007 - Vermicompost as a soil supplement to improve growth, yield and fruit quality of tomato (Lycop- ersicum esculentum). - Bioresource Technol., 98(15): 2781- 2786. JONER E.J., JAKOBSEN I., 1995 - Growth and extracellular phosphate activity of arbuscular mycorrhizal hyphae as in- fluenced by soil organic matter. - Soil Biol. Biochem., 27(9): 1153-1159. KARIMAN K., GOLTAPEH E.M., MINASSIAN V., 2005 - Ar- buscular mycorrhizal fungi from Iran. - J. Agr. Tech., 1: 301- 313. KORMANIK P.P., MCGRAW A.-C., 1982 - Quantification of vesicular-arbuscular mycorrhizae in plant roots, pp. 37-45. - In: SCHENCK N.C. (ed.) Methods and principles of mycor- rhizal research. The American Phytopathological Society, St. Paul, Minnesota, USA, pp. 244. KRISHNA A., BIRADARPATIL N., CHANNAPPAGOUDAR B., 2008 - Influence of system of rice intensification (SRI) cultivation on seed yield and quality. - Karnataka J. Agric. Sci., 21: 369-372. LINDERMAN R.G., DAVIS E.A., 2004 - Evaluation of com- mercial inorganic and organic fertilizer effects on arbuscu- lar mycorrhizae formed by Glomus intraradices. - HortTech., 14: 196-202. LOPEZ S., MAROTO J.V., SAN BAUTISTA A., PASCUAL B., ALAGARDA J., 2000 - Qualitative changes in pepino fruits following preharvest applications of ethephon. - Sci. Hortic., 83: 157-164. MAHMOOD I., RIZVI R., 2010 - Mycorrhiza and organic farming. - Asian J. Plant Sci., 9: 241. MARSCHNER H., 1995 - Mineral nutrition in higher plants. - Academic Press London, UK. MENA-VIOLANTE H.G., OCAMPO-JIMÉNEZ O., DEN- DOOVEN L., MARTÍNEZ-SOTO G., GONZÁLEZ- CASTAÑEDA J., DAVIES F.T., OLALDE-PORTUGAL V., 2006 - Arbuscular mycorrhizal fungi enhance fruit growth and quality of chile ancho (Capsicum annuum L. cv San Luis) plants exposed to drought. - Mycorrhiza, 16: 261-267. MORADITOCHAEE M., BOZORGI H.R., HALAJISANI N., 2011 - Effects of vermicompost application and nitrogen fertil- izer rates on fruit yield and several attributes of eggplant (Sola- num melongena L.) in Iran. - World Appl. Sci. J., 15: 174-178. ORTAS I., HARRIS P.J., ROWELL D.L. 1996 - Enhanced up- take of phosphorus by mycorrhizal sorghum plants as influ- enced by forms of nitrogen. - Plant Soil., 184: 255-264. PROHENS J., RUIZ J.J., NUEZ F., 1996 - The pepino (Sola- num muricatum, Solanaceae): A “new” crop with a history. - Econ. Bot., 50: 355-368. RAMAN N., MAHADEVAN A., 1996 - Mycorrhizal research: A priority in agriculture. - In: MUKERJI K.G. (ed.) Con- cepts in mycorrhizal research. Kluwer Academic Publishers, Dordrecht, The Netherlands. REGVAR M., VOGEL-MIKUŠ K., ŠEVERKAR T., 2003 - Ef- fect of AMF inoculum from field isolates on the yield of green pepper, parsley, carrot, and tomato. - Folia Geobotanica, 38: 223-234. ROBERTS P., JONES D.L., EDWARDS-JONES G., 2007 - Yield and vitamin C content of tomatoes grown in vermicom- posted wastes. - J. Sci. Food Agr., 87: 1957-1963. ROUPHAEL Y., CARDARELLI M., DI MATTIA E., TULLIO M., REA E., COLLA G., 2010 - Enhancement of alkalin- ity tolerance in two cucumber genotypes inoculated with an arbuscular mycorrhizal biofertilizer containing Glomus in- traradices. - Biol. Fert. Soil., 46: 499-509. 42 SABLE C., GHUGE T., JADHAV S., GORE A., 2007 - Impact of organic sources on uptake, quality and availability of nu- trients after harvest of tomato. - J. Soil Crop., 17: 284-287. SOHN B.K., KIM K.Y., CHUNG S.J., KIM W.S., PARK S.M., KANG J.G., RIM Y.S., CHO J.S., KIM T.H., LEE J.H., 2003 - Effect of the different timing of AMF inoculation on plant growth and flower quality of chrysanthemum. - Sci. Hortic., 98: 173-183. SUBRAMANIAN K.S., SANTHANAKRISHNAN P., BALA- SUBRAMANIAN P., 2006 - Responses of field grown to- mato plants to arbuscular mycorrhizal fungal colonization under varying intensities of drought stress. - Sci. Hortic., 107: 245-253. TARKALSON D.D., JOLLEY V.D., ROBBINS C.W., TERRY R.E., 1998 - Mycorrhizal colonization and nutrient uptake of dry bean in manure and compost manure treated sub- soil and untreated topsoil and subsoil. - J. Plant Nut., 21: 1867-1878. TOMATI U., GRAPPELLI A., GALLI E., 1983 - Fertility fac- tors in earthworm humus, pp. 49-56. - In: TOMATI U., and A. GRAPPELLI (eds.) International symposium on agricul- tural environment. prospects in earthworm farming. Ministe- ro della Ricerca Scientifica e Tecnologia, Rome. Tipolitogra- fia Euromoderna, Modena, Italy. TOMATI U., GRAPPELLI A., GALLI E., 1987 - The presence of growth regulators in earthworm-worked wastes, pp. 423- 435. - In: BONVICINI PAGLIOI A.M., and P. OMODEO (eds.) International Symposium on Earthworms, Selected Symposia and Monographs, 1987 Unione Zoologica Itali- ana, Modena, Italy. TRIMBLE M.R., KNOWLES N.R., 1995 - Influence of ve- sicular-arbuscular mycorrhizal fungi and phosphorus on growth, carbohydrate partitioning and mineral nutrition of greenhouse cucumber (Cucumis sativus L.) plants during es- tablishment. - Can. J. Plant Sci., 75: 239-250. VAMERALI T., SACCOMANI M., BONA S., MOSCA G., GUARISE M., GANIS A., 2003 - A comparison of root characteristics in relation to nutrient and water stress in two maize hybrids. - Plant Soil, 255: 157-167. VAN DER HEIJDEN M.G., BOLLER T., WIEMKEN A., SANDERS I.R., 1998 - Different arbuscular mycorrhizal fungal species are potential determinants of plant commu- nity structure. - Ecology, 79: 2082-2091. ZAREI M., KÖNIG S., HEMPEL S., NEKOUEI M.K., SAV- AGHEBI G., BUSCOT F., 2008 - Community structure of arbuscular mycorrhizal fungi associated to Veronica rech- ingeri at the Anguran zinc and lead mining region. - Environ. Pollut., 156: 1277-1283.