INFLUENCE OF TWO AM FUNGI IN IMPROVEMENT OF MINERAL PROFILE IN ARACHIS HYPOGAEA L. UNDER SALINITY STRESS

Transcription

1 Legume Res., 37 (3) : , 2014 doi: / AGRICULTURAL RESEARCH COMMUNICATION CENTRE INFLUENCE OF TWO AM FUNGI IN IMPROVEMENT OF MINERAL PROFILE IN ARACHIS HYPOGAEA L. UNDER SALINITY STRESS Promita Datta and Mohan Kulkarni* Division of Biochemistry, Department of Chemistry, University of Pune, Pune , India Received: Accepted: ABSTRACT Increasing salinization of fertile soil is becoming a serious agricultural problem. Arbuscular mycorrhizal (AM) fungi improve plant growth by improving nutrient mobilization under salt stress. A greenhouse experiment was undertaken to check effect of Glomus mosseae, Glomus fasciculatum on mineral uptake of Arachis hypogaea under various salinity stresses. The experiment comprised of five salinity levels (EC: 1.04 (control), 2.10, 3.78, 5.94, 8.26 ds/m) and four mycorrhizal status as non-mycorrhizal (uninoculated), G. mosseae and G. fasciculatum individually and their mixed inoculation. Under salinity stress, mycorrhiza inoculated plants showed significant increase in Cu, Zn, K/Na, Mg/Na and Ca/Na ratios but, highest accumulation (P: 53.33%, Cu: 34.36%, Zn: 21.52%, Ca/Na: 50.43%, K/Na: 42.06% and Mg/Na: 57.26%) was observed in plants inoculated with mixed mycorrhizal fungi. Hence, in amelioration of salinity stress and to prevent nutrient imbalance in A. hypogaea plant, G. mosseae and G. fasciculatum in mixed treatment can be used. Key words: Arachis. hypogaea, Glomus mosseae, Glomus fasciculatum, Salinity stress, Mineral profile. INTRODUCTION experienced. To maintain soil health and to improve Salinization of agricultural fertile soil is an ground nut production, chemical fertilizers are used ever-increasing serious problem affecting agricultural extensively in India (Singh et al., 2011). But, the productivity. Around 7% of earth s land surface has indiscriminate applications of chemical fertilizers at become saline and by the middle of 21 st century, it high doses cause soil pollutions and the residues of would result in 50% land loss due to increased heavy metals and pollutants remain persistent in salinization (Wang et al., 2003). Soil salinity reduces agricultural products. H ence, an alternative absorption of essential mineral elements mainly approach to chemical fertilizers to improve plant phosphorus because of precipitation of phosphate growth under abiotic stress conditions involves ion with other cations such as Ca + 2, Mg + 2 etc. inoculation of plant with Arbuscular mycorrhizal Arachis hypogaea L. is an important oil seed crop (AM) fungi. AM fungi are associated with roots of and is also valued for its high protein content and is over 80% terrestrial plant species and their a rich source of calcium, iron, vitamin etc. In India, association is characterized by bi-directional ground nut is mainly cultivated in parts of exchange of essential nutrients between plants and Maharashtra, Guarat and Andhra Pradesh. But, its soil fungi (Heiden et al., 1998). Association of AM production in these regions is steadily declining fungi protects plant from detrimental effect of salt stress because of erratic rainfall and nutrient deficiencies by enhancing the uptake of mineral elements from in soil. It is reported that, phosphorus is one of the soil to plant and improves their translocation (Sharifi maor nutrient which improves yield and quality of et al., 2007). There are several reports, which indicate ground nut (Patel et al., 1990). But, in saline soil it that mycorrhizal inoculation alleviates salt stress and becomes unavailable to plant because of its rapid improves growth of various plants, mostly with single precipitation. Other than phosphorus, calcium is also isolate (Gharineh et al., 2009). But, information required for development of ground nut pod and due regarding enhancement of mineral profile of ground to its deficiency in soil; a substantial yield loss is nut (Arachis hypogaea) under salt stress, in presence * Corresponding author s drmvkulkarni@gmail.com.

2 322 LEGUME RESEARCH- An International Journal of two AM fungi, as an individual and in combined inoculation is limited. Therefore, the present study was aimed to investigate the effect of two AM fungi (one indigenous AM isolate from saline and other from non saline habitat) inoculated individually and together in A. hypogaea under salinity stress treatment with respect to mineral acquisition. MATERIALS AND METHODS Mycorrhizal inoculation, plant material and experimental design:am spores were extracted from saline-sodic soil (ph: 10.2, EC: 5.8dS/m, sodium absorption ratio: 17) of Lonar Crater Lake, Buldhana ( "N, "E), a salt lake, in December 2009, by wet sieving and decanting method (Gerdemann and Nicolson, 1963). The most dominant AM fungal species, Glomus mosseae (Nicol. & Gerd.) was isolated and propagated in pot culture with Zea mays L. plant in the same autoclaved soil collected from sampling site. Z. mays plant was allowed to grow for three months under greenhouse conditions. After three months, plant shoots were removed from soil surface and roots were chopped in fine pieces and then thoroughly mixed with soil. This mixture was considered as soil based inoculum, which consisted of AM spores of G. mosseae (spore density: 150 to 160 spores/10g air-dri ed soil), AM colonized roots (~ 75% colonization). AM spores of Glomus fasciculatum (Thaxt.) Gerd. and Trappe were obtained from T. Stanes and Company Limited, Coimbatore as a starter culture and was maintained on Z. mays plant for one month in greenhouse. After one month, soil based inoculum (spore density: 100 to 110 spores/ 10g air-dried soil, AM colonized root: ~ 75% colonization) was used for further study. Seeds of A. hypogaea (cv. T.G.-26) used in this study were obtained from Amar Seeds Pvt. Ltd., Pune, Maharashtra. Seeds were surface sterilized using sodium hypochlorite solution (0.5%, w/v) : reverseosmosis water (1:3) and were allowed to germinate on moist filter paper. At first true leaf stage, seedlings of almost equal length was transplanted in 3kg plastic pot containing autoclaved (at C, 103.4kPa, 1h), slity loam soil (sand: 35%, slit: 57%, clay: 8%) with soil properties ph: 6.0, electrical conductivity (EC): 1.04dS/m, organic matter: 1.3%, available P: 0.7mg/ 100g, available N: 0.12mg/100g and available K: 0.45mg/100g. The experiment was designed in randomized block design, comprised of four mycorrhizal treatments (NM: non-mycorrhizal (uninoculated), Gm: G. mosseae inoculated, Gf: G. fasciculatum inoculated, mixed( Gm+ Gf) both G. mosseae and G. fasciculatum inoculated) and five salinity levels (EC: 1.04 (control), 2.10, 3.78, 5.94, 8.26dS/m) with four replicates (three plants per replicate). To achieve ~ 800 spores per pot, 50g of G. mosseae inoculum and 75g of G. fasciculatum inoculum were used in Gm and Gf treatment respectively. In case of mixed treatment, 25g of G. mosseae inoculum and 40g of G. fasciculatum inoculum were used. In all the cases, respective soil based inoculum was placed 3cm below the seedling ust pri or to seedli ng transplantation. Whereas, non-mycorrhizal plants did not receive any mycorrhizal inoculum. The amount of soil based inoculum used in three mycorrhizal treatments (G. mosseae, G. fasciculatum and mixed) was based on the results obtained in the previous study, using same host plant. Where, almost equal number of spores was developed after sixty days of mycorrhizal inoculation. A constant soil volume (3kg) was kept in all the mycorrhizal and non-mycorrhizal treatments. Plants were irrigated with tap water (sieved through 105 sieve) every alternate day and with P-free Hoagland solution (X/ 10) twice in a month (Hoagland and Arnon, 1940). After each irrigation, pots were weighed to maintain water content constant. Salinity stress was provided by applying NaCl solutions in pots after one month of seedling transplantation. NaCl solutions of 50, 100, 150 and 200mM were supplied in 3kg soil to raise electrical conductivity to 2.10, 3.78, 5.94 and 8.26dS/m respectively. NaCl solution was not supplied in control pot and soil from control pot conferred EC value of 1.04dS/m. Salinity stress was increased gradually to prevent shock and was supplied until the target salinity level (in terms of EC value) was achieved. Irrigation was done in such a way to prevent leaching of nutrient solution as well as water. The whole study was conducted in greenhouse (temperature of 30/20 0 C day/night, a relative humidity of 60-65% and at a photon flux intensity of around mol/m 2 /s). Extent of AM root colonization: After sixty days of seedling transplantation, plants from each treatment were harvested and analyzed for

3 estimation of per cent root colonization and mineral profile. Roots from three replicates were used for analysis of root colonization (%). Cleaned root segments of 1cm length were cleared in hot KOH (10%, w/v) and stained with trypan blue (0.05%, w/ v) followed by observation under trinocular compound microscope and colonization percentage was calculated by the grid-line intersect method (Phillips and Hayman, 1970; Giovannetti and Mosse, 1980). Plant mineral content:plants from remaining replicates were cleaned with reverse-osmosis water and kept in oven for drying (at 60 0 C for 12h) and dry weight was recorded. Dried plants were powdered and used for determining mineral contents. The powdered material was digested in nitric-perchloric acid mixture (6:1) and phosphorus was analyzed by vanadate-molybdate method (Hanson, 1950). Sodium, potassium, calcium, magnesium, copper and zinc concentrations of each sample were estimated by atomic absorption spectrophotometer (Perkin Elmer 603) and chloride content in each powered sample was determined using Spectro Xepos XRF analyzer. Statistical analysis: Data obtained were analyzed statistically using SPSS v.9.0 software. Analysis of variance was used to examine experimental factors and their interaction. Treatment means were compared by Duncan s Multiple Range Test (p< 0.05). RESULTS AND DISCUSSION Under control (1.04dS/m) and various salinity treatments (2.10 to 8.26dS/m), all the mycorrhizal inoculated plants were found to be colonized. But, plants inoculated with mixed mycorrhizal fungi showed higher amount of root length colonized at each salinity treatment than the plants inoculated with G. mosseae and G. fasciculatum fungi individually (Fig. 1.). Magnitude of root colonization significantly (p< 0.05) reduced with increase in salinity stress in all the mycorrhizae inoculated plants. Plants from control treatment (1.04dS/m) had 57.8, 51.5 and 64.5% root colonized following individual inoculation with G. mosseae and G. fasciculatum isolates and with their mixed inoculation in A. hypogaea plant respectively. Whereas, with increase in salinity gradient from 2.10 to 8.26 ds/m, the extent of root colonization was Vol. 37, No. 3, reduced from to 31.7%, 46.5 to 30.7% and 55.3 to 40% in G. mosseae, G. fasciculatum and mixed inoculated plants. The reduction in percentage root colonization with increase in salinity stress suggests that, salt concentrations in the soil affect extent of mycorrhizal colonization in A. hypogaea plant roots. This finding was supported by previous report that; addition of salts to the soil solution was responsible for hyphal growth inhibition as well as less colonization in host root (Ruiz-Lozano and Azcón, 2000). Plants without mycorrhizal inoculation remained non-mycorrhizal during the study. In the present study, at each level of salinity gradient from 2.10 to 8.26dS/m, mycorrhizae inoculated plants had more calcium and less sodium concentrations than uninoculated plant and these resulted in increase in magnitude of Ca:Na ratio in mycorrhizae inoculated plants. With increase in salinity stress from 2.10 to 8.26dS/m, mixed mycorrhizae inoculated plant had significantly (p< 0.05) more Ca:Na ratio (3.47 to 0.86) followed by individual G. mosseae (3.21 to 0.73) and G. fasciculatum (2.95 to 0.66) inoculated and uninoculated plant (2.5 to 0.58) (Fig. 2.). Whereas, in control treatment (1.04dS/m), uninoculated plant showed significantly (p< 0.05) higher Ca:Na ratio than all mycorrhizae inoculated plants (G. mosseae, G. fasciculatum and mixed) (Fig. 2.). Similar type of result obtained by Cantrell and Linderman (2001) in mycorrhiza treated lettuce plant. Percentage enhancement of Ca:Na ratio over uninoculated plant was observed in the decreasing order of mixed> G. mosseae> G. fasciculatum inoculated plant under each level of salinity stress (2.10 to 8.26dS/m). However, as compared to uninoculated plant, maximum increase in Ca:Na ratio up to 32.17, and 50.43% was observed at 5.94dS/m in respective G. mosseae, G. fasciculatum and mixed mycorrhizae inoculated plant. Improvement of Ca + 2 ion uptake by all the three mycorrhizal treatments (G. mosseae, G. fasciculatum and mixed) and reduced uptake of Na + ion might be an important mechanism to protect A. hypogaea from deleterious effects of soil salinity and to make it salt adapted (Cramer et al., 1985). G. mosseae, G. fasciculatum and mixed mycorrhizal inoculation in A. hypogaea increased potassium uptake as compared to uninoculated plant

4 324 LEGUME RESEARCH- An International Journal TABLE 1: Total copper (ppm), zinc (ppm), phosphorus (%) and chloride (mg/g) content of mycorrhiza treated (Gm, Gf and Gm+ Gf) and untreated (NM) plant under different salinity treatments (1.04, 2.10, 3.78, 5.94 and 8.26dS/m). Salinity(dS/m) Mycorrhizal Total Cu Total Zn Total P Total Chloride treatment 1.04 NM ± h ± d 1.319± bc 5.899± r Gm ± d ± b 1.421± ab 6.728± p Gf ± e ± c 1.386± b 6.235± q Gm+ Gf ± a ± a 1.509± a 7.269± o 2.10 NM ± i ± h 1.049± ef 7.299± o Gm ± c ± f 1.157± de 8.308± m Gf ± f ± g 1.113± de 7.896± n Gm+ Gf ± b ± e 1.222± cd 8.792± l 3.78 NM 8.901± o ± l 0.781± hi ± h Gm ± ± ± g ± Gf ± l ± k 0.842± gh ± i Gm+ Gf ± g ± i 0.945± fg 9.564± k 5.94 NM 7.803± r 5.389± p 0.519± lm ± c Gm 9.679± m 6.259± n 0.633± k ± g Gf 9.223± n 5.854± o 0.590± kl 12.13± f Gm+ Gf ± k 6.545± m 0.721± i ± i 8.26 NM 6.621± t 2.430± t 0.461± mn ± a Gm 8.128± q 2.721± r 0.395± n ± d Gf 7.690± s 2.579± s 0.345± n ± b Gm+ Gf 8.798± p 2.829± q 0.456± mn 12.21± e NM: non mycorrhizal, Gm: Glomus mosseae, Gf: Glomus fasciculatum, Gm+ Gf: Glomus mosseae + Glomus fasciculatum, Values are mean± SE of three replicates. Within column, different letters for each treatment indicate statistically significant difference (p< 0.05) by Duncan s Multiple Range Test after performing ANOVA. under control (1.04dS/m) and at each level of salinity treatments (2.10 to 8.26dS/m) and hence, with increase in salinity stress from 2.10 to 8.26dS/m, all the three types of mycorrhizal inoculations (G. mosseae, G. fasciculatum and mixed) significantly (p< 0.05) i mproved plant K: Na rati o over uninoculated plant. But, in control treatment (1.04dS/m), significantly (p< 0.05) higher K:Na ratio was observed in uninoculated plant than G. mosseae, G. fasciculatum and mixed mycorrhizae inoculated plant (Fig. 3.). In fact, at each level of salinity (2.10 to 8.26dS/m), mixed mycorrhizal inoculation found superior in response to improvement of K:Na ratio as well as in enhancement of its magnitude in A. hypogaea plant followed by G. mosseae, G. fasciculatum inoculation. In mixed and G. fasciculatum inoculated plant, maximum increment (42.06 and 17.76% respectively) of K:Na ratio over uninoculated plant was found at 5.94dS/ m salinity stress and by further increase in stress up to highest level (8.26dS/m), a sudden decrease in magnitude (33.96 and 13.21% respectively) as compared to uninoculated plant was observed (Fig. 3.). Whereas, G. mosseae inoculation increased K:Na ratio maximally up to 22.94% at 3.78dS/m salinity stress over uninoculated plant and by further increase in stress (5.94 and 8.26dS/m), a reduction in percentage increment (29.91 and 22.64% respectively) was observed. Mycorrhizal inoculations positively influenced in increment of potassium concentration and consequently enhanced K:Na ratio which is supported by previous study, where more K:Na ratio in shoot and root tissues of AM plant was found (Giri et al., 2007). Under salinity stress, higher K:Na ratio is beneficial in maintaining ionic balance in cytoplasm and protects plant from disruption of several metabolic processes (Allen and Cunningham, 1983). A similar type of trend was also observed in case of plant s Mg:Na ratio increment by mycorrhizal inoculations (Fig. 4.). At provided salinity treatments (2.10 to 8.26dS/m), over uninoculated plant, percentage accumulation of Mg:Na ratio in mycorrhizae inoculated plant was found in decreasing order of mixed> G. mosseae> G. fasciculatum inoculation. Even though, at 2.10 to 8.26dS/m salinity stress, all the mycorrhizae inoculated plants had better Mg:Na ratio over uninoculated plants but maximum enhancement was observed at 5.94dS/m salinity stress level. At this

5 i Vol. 37, No. 3, E x t e n t o f ro o t c o l o n i z a tio n ( % ) b l c d a d e f i e b c f d e fh f g d e g h i S a l ini ty tr e a tm e n t ( ds / m ) e fg N M G m G f G m + G f FIG.1: Extent of mycorrhizal root colonization (%) of A. hypogaea plant inoculated with mycorrhizae (Gm, Gf and Gm + Gf) and without mycorrhiza (NM) under different salinity treatments (1.04, 2.10, 3.78, 5.94 and 8.26dS/m). [Bars of each treatment followed by different letters indicate statistically significant difference (p< 0.05) by Duncan s Multiple Range Test after performing ANOVA]. salinity stress level, Mg:Na ratio was improved by 37.9, and 57.26% in G. mosseae, G. fasciculatum and mixed mycorrhizae inoculated plant respectively in comparison with uninoculated plant. Under salt stress, improvement of Mg + ion uptake and reduction in Na+ ion uptake by mycorrhizal inoculation was also reported by Giri and Mukeri (2004). Salinity in soil solution induces less magnesium uptake and declines chlorophyll biosynthesis but, better accumulation of Mg:Na ratio by mycorrhizal plant helps in increasi ng photosynthetic efficiency even under salt stress and reduces the rate of impairment of photosynthesis (Giri and Mukeri, 2004). The concentrations of copper and zinc were found significantly (p< 0.05) higher in plants belonging to control treatment (1.04dS/m) and the values were reduced significantly (p< 0.05) by gradual increase in salinity stress level from 2.10 to 8.26dS/m regardless of mycorrhizae inoculations and uninoculation (Table 1). In fact, concentrations of both these elements were found significantly (p< 0.05) more in mycorrhizae inoculated plants than uninoculated plant at control (1.04dS/m) and salinity stress levels (2.10 to 8.26dS/m) and it may be because of improved absorption and translocation of copper and zinc ions by mycorrhizal hyphae among mycorrhizae inoculated plants (Giri et al., 2007). Data from Table 1 indicated that, at each level of salinity treatment (2.10 to 8.26dS/m), the h i C a :N a R a tio a c b c g e d h g m k S a lin i ty tre a tm e n t ( d S /m ) N M G m G f G m + G f p o o p FIG.2: Ca:Na ratio of A. hypogaea plant inoculated with mycorrhizae (Gm, Gf and Gm + Gf) and without mycorrhiza (NM) under different salinity treatments (1.04, 2.10, 3.78, 5.94 and 8.26dS/m). [Bars of each treatment followed by different letters indicate statistically significant difference (p< 0.05) by Duncan s Multiple Range Test after performing ANOVA]. concentrations of copper and zinc ions as well as their accumulations over uninoculated plant were found in decreasing order of mixed> G. mosseae> G. fasciculatum inoculated plant. In the control treatment (1.04dS/m), in comparison wi th uninoculated plant, G. mosseae, G. fasciculatum individual and their mixed inoculation in A. hypogaea accumulated copper and zinc ions by 8.06, 6.88%; 5.76, 3.87% and 15.23, 8.70% respectively. It was also observed that, at 5.94dS/m salinity level, maximum accumulations of copper and zinc ions by 24.10, 16.14% (in G. mosseae inoculated plant); 18.21, 8.53% (in G. fasciculatum inoculated plant) and 34.36, 21.52% (in mixed mycorrhizae inoculated plant) noticed over uninoculated plant. By further increase in salinity stress up to the highest level (8.26dS/m), a reduction in percentage accumulation of copper ion (in G. mosseae plant: 22.81%, in G. fasciculatum inoculated plant: 16.16% and in mixed inoculated plant: 32.93%) and zinc ion (in G. mosseae plant: 11.93%, in G. fasciculatum inoculated plant: 6.17% and in mix inoculated plant: 16.46%) over uninoculated plant was observed. The findings of this experiment are in consistent with previous reports where, better copper uptake i n G. fasciculatum inoculated Acacia nilotica and more zinc uptake in G. etunicatum inoculated Glycine n

6 t r t l i f 326 LEGUME RESEARCH- An International Journal 6 5 a c b d e N M G m G f G m +G f a c b d K :Na R atio g k h p n o m q h g m k n r s 4 p 1 s 2 o e l i f N M G m G f G m +Gf M g:n a R atio q Salinity treatme nt (ds/m ) 8.26 FIG. 3: K:Na ratio of A. hypogaea plant inoculated with mycorrhizae (Gm, Gf and Gm + Gf) and without mycorrhiza (NM) under different salinity treatments (1.04, 2.10, 3.78, 5.94 and 8.26dS/m). [Bars of each treatment followed by different letters indicate statistically significant difference (p< 0.05) by Duncan s Multiple Range Test after performing ANOVA]. max were observed (Sharifi et al., 2007; Giri et al., 2007). Irrespective of mycorrhizal inoculations, all the plants from control treatment (1.04dS/m) had more phosphorus content than salinity stressed (2.10 to 8.26dS/m) plants and reduction in total phosphorus content varied significantly (p< 0.05) among individual mycorrhizal inoculation with increase in salinity gradient (Table 1). It was also noted that, at each level of salinity treatments (2.10 to 8.26dS/m) and in control treatment (1.04dS/m), mycorrhizal inoculation improved total phosphorus content in A. hypogaea plant over uninoculated plant and the difference was non significant among mycorrhizal inoculations (uninoculated, G. mosseae, G. fasci culatum and mixed). Compared to uninoculated plant, G. mosseae, G. fasciculatum and mixed mycorrhizae inoculation improved phosphorus content by 7.58, 5.30 and 14.39% respectively in control treatment (1.04dS/m). Whereas, with increase in salinity gradient from 2.1 to 8.26dS/m, percentage accumulation of phosphorus content over uninoculated plant was observed in the range of to 33.33% (in G. mosseae inoculated plant); 5.71 to 16.67% (in G. fasciculatum inoculated plant) and to 53.33% (in mixed mycorrhizae inoculated plant). During the event of mycorrhizal association, extended hyphal network of AM fungi could easily access less Sa linity trea tmen t (ds/m ) FIG.4: Mg:Na ratio of A. hypogaea plant inoculated with mycorrhizae (Gm, Gf and Gm + Gf) and without mycorrhiza (NM) under different salinity treatments (1.04, 2.10, 3.78, 5.94 and 8.26dS/m). [Bars of each treatment followed by different letters indicate statistically significant difference (p< 0.05) by Duncan s Multiple Range Test after performing ANOVA]. mobile phosphorus from depletion zone around host roots and effectively improve its uptake. By positively enhancing uptake and inflow of phosphorus in host plant, AM fungi actually counterbalanced the adverse effects of soil salinity (Ezawa et al., 2002). At control (1.04dS/m) and minimum salinity stress (2.1dS/m) level, mycorrhizal plants (G. mosseae, G. fasciculatum and mixed) had significantly more chloride content than uninoculated plant (Table 1). But, at higher level of salinity stress (3.78 to 8.26dS/m), G. mosseae, G. fasciculatum and mixed mycorrhizal inoculation with A. hypogaea plant significantly (p< 0.05) reduced the uptake of chloride ion compared to uninoculated plant. At these salinity stress levels (3.78 to 8.26dS/m), mixed mycorrhizal inoculation resulted in the maximum reduction in chloride ion uptake over uninoculated plant and was in the range of to 17.79% whereas, G. mosseae, G. fasciculatum inoculation reduced chloride ion uptake maximally up to and 8.29% respectively. Thus, with increase in salinity stress (3.78 to 8.26dS/m) uninoculated plant acquired more chloride ions. While, plants inoculated with G. mosseae, G. fasciculatum and mixed mycorrhizal fungi had less chloride content regardless of salinity exposures. Detrimental effects of salinity on host plant is reduced to some extent after mycorrhizal colonization as AM fungi reduced the

7 uptake and translocation of chloride ion in plant. Similar type of result observed in sweet basil where mycorrhizal colonization deprived chloride uptake and improved plant growth under salinity stress (Zuccarini and Okurowska, 2008). Salinity stress and mycorrhizal treatments when considered individually as well as their interaction, had a significant (p< 0.05) effect on enhancement of Ca:Na, K:Na, Mg:Na ratios and better uptake of copper, zinc and chloride ion. Mycorrhizal effect at each level of salinity, found non significant (p< 0.1) on P uptake but, individual effect of salinity stress and interactive effect of mycorrhiza and salinity stress have significant (p< 0.05) impact on P uptake. It is known that, soil salinity results in nutrient imbalance in plants when accumulation of beneficial ions (Ca + 2, K +, Mg + 2 etc) is replaced by harmful ions (Na + and Cl - ) and this event creates adverse physiological changes in host plant. But, by inoculation of A. hypogaea with G. mosseae, G. fasciculatum and their mixed mycorrhizal fungi, improved uptake of Ca + 2, K +, Mg + 2 ions and reduced Na + and Cl - ion concentrations and by this they consequently enhanced more Ca:Na, K:Na, Mg:Na ratios under provided salinity treatments. Selection and translocation of beneficial ions by AM fungi can then be an important strategy to alleviate adverse salinity effects on plant growth. Salinity in soil also interferes with phosphorus mobilization and their transportation (Munns, 1993). But, mycorrhizal inoculation in A. hypogaea had better phosphorus concentration than uninoculated plant under provided salinity treatments (2.10 to 8.26dS/m) and this finding indicated that, toxic effects of Na + and Cl - ions are reduced by improving phosphorus translocation. At each level of salinity stress (2.10 to Vol. 37, No. 3, dS/m) mycorrhizal inoculations reduced uptake of Na + and Cl - ions as compared to uninoculated plant and this phenomenon is important in reducing osmotic disturbances and to maintain normal cellular functions. Moreover, in all mycorrhizal plants, maximum enhancement of Ca:Na, K:Na, Mg:Na ratios and better accumulation of zinc, copper and phosphorus contents over uninoculated plant occurred at 5.94dS/m. Whereas, mixed mycorrhizal fungi showed profound effect in this respect and this may suggest that, nutrient deficiencies in A. hypogaea can be overcome better by mixed inoculation of G. mosseae, G. fasciculatum followed by their individual associations under salinity stresses. CONCLUSION Thus, it can be concluded that, though salinity stress reduced the uptake of several mineral elements (P, Cu, Zn, K: Na, Ca:Na, Mg:Na), mycorrhizal treatments (G. mosseae, G. fasciculatum and mixed) improved their uptake and overcome nutrient imbalance by reducing uptake of chloride ion. It was also indicated that, the highest accumulation of all these mineral elements observed at 5.94dS/m salinity stress and among three mycorrhizal treatments, inoculation with mixed mycorrhizal fungi found superior with respect to better mineral accumulation. Hence, mixed treatment of G. mosseae and G. fasciculatum fungi can be used in association with A. hypogaea plant in alleviation of adverse salinity effect and in prevention of toxic nutrient uptake. ACKNOWLEDGEMENT Authors express sincere thanks to Department of Biotechnology, New Delhi for the financial support. REFERENCES Allen, E.B. and Cunningham, G.L., (1983), Effects of vesicular arbuscular mycorrhizae on Distichlis spicata under three salinity levels, New Phytol 93: Cantrell, I.C. and Linderman, R.G., (2001), Preinoculation of lettuce and onion with VA mycorrhizal fungi reduces deleterious effects of soil salinity, Plant Soil 233: Cramer, G.R., Lauchli, A. and Polito, V.S., (1985), Displacement of Ca 2+ by Na + from the plasmalemma of root cells: a primary response to salt stress, Plant Physiol 79: Ezawa, T., Smith, S.E. and Smith, F.A., (2002), P metabolism and transport in AM fungi, Plant Soil 244: Gerdemann, J.W. and Nicolson, T.H., (1963), Spores of mycorrhizal Endogene species extracted from soil by wet sieving and decanting, Trans Br Mycol Soc 46: Gharineh, M.H., Nadian, H., Fathi, G., Siadat, A. and Maadi, B., (2009) Role of arbuscular mycorrhizae in development of salt-tolerance of Trifolium alexandrinum plants under salinity stress, JFAE 7:

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