Citrus is grouped under the salt sensitive crops. Mycorrhizal fungi, a symbiotic relationship between plant roots and beneficial fungi, are supposed to impart the stress tolerance in the host plants. The stress tolerance improved due to Arbuscular Mycorrhizal fungi (AM fungi) colonization can be attributed to enhanced mineral nutrition. In the present study the efforts are made to evaluate the effectiveness of AM fungi with two citrus genotypes under salt stress. Three-month-old seedlings of Karna Khatta (Citrus Karna) and Troyer Citrange (Poncirus trifoliata × Citrus sinensis) were inoculated with the indigenous soil based AM inocula (mixed strains). The salinity gradient was developed by frequent irrigation with NaCl (0, 50, 100, 150 mM w/v). The results indicated that all the physical parameters were affected with increasing salinity. The proline accumulation increased while the chlorophyll, calcium and magnesium contents decreased significantly with increasing salinity. In general, the decreased AM colonization did not show any significant effects under salt stress. Keywords: Citrus karna; Poncirus trifoliata × Citrus sinensis; 71treatment. The available phosphorus content in the substrate was 63.2 ppm. The soil based mycorrhizal inocula (Glomus sp., Gigaspora sp., spores) procured from the Division of Microbiology, I.A.R.I., New Delhi, were applied (ca. 300 spores/100 g soil) in the root zone (V1 -non-mycorrhized control, V2 -mycorrhized) while transplanting the seedlings. The salinity gradients were developed by regular irrigation with salt water with NaCl (S1 -control, S2 -50, S3 -100 and S4 -150mM w/v).The physical parameters viz. number of leaves, stem diameter and height of seedling were recorded 90 days after planting (90 DAP). The mean values of three replicates were given. The root colonization by Arbuscular Mycorrhizal fungi (AM fungi) was observed at the end of experiment i.e. 90 DAP. The percentage of root colonization was recorded using the method defined by Phillips and Hayman (1970).All the biochemical estimations were done at the end of the experiment, i.e. 90 DAP. The proline estimation was done using the shoot tip portions (stem and leaves) of fresh plant samples according to Bates et al. (1973), while the chlorophyll estimation was done by using only tender leaves according to Barnes et al. (1992). The total sugars and reducing sugars estimations were done by the Nelson-Somogyi method using oven dried samples as described by Thimmaiah (2004).The macro-and micronutrient analyses were done by using the oven dried whole plant samples. The seedlings were uprooted from pots and washed with dilute acid (HCl N / 10 N) and then rinsed thrice with distilled water. The excess water was wiped with tissue paper and then the seedlings were oven dried at 60°C for three days. The brittle and well-dried plant samples were crushed to a powder and 500 mg of ground sample was digested with diacid solution (HNO 3 and HClO 4 , 9:4). This extract was used for the estimation of phosphorus, potassium, ...

  The present investigation was undertaken to find out efficient strains of arbuscular mycorrhiza (AM fungi) alone or in combinations with Trichoderma viride for inoculation Dendrocalamus strictus L. seedlings. The inoculated seedlings showed good response having higher plant height, phosphorous ions content in root and shoot, AM spore number and root colonization than non-inoculated (control) seedlings in both single (alone) and co-inoculation (combined consortium) experiments. T. viride showed significant growth followed by Glomus mosseae, G. fasciculatum and mixed AM with single inoculation. In co-inoculation, the best growth responses were observed with G. fasciculatum + T. viride followed by G. mosseae + T. viride, mixed vesicular arbuscular mycorrhizas (VAM) + T. viride, G. mosseae + G. fasciculatum + T. viride + mixed VAM, G. mosseae + G. fasciculatum + T. viride and G. mosseae + G. fasciculatum after 120 days and also depicted maximum increase in phosphorus content of shoot and root when compared with other inoculated seedlings. However, all the inoculated seedlings showed significant increase in phosphorus content when compared with control seedlings.

ABSTRACT:In vitro selected salt tolerant saplings of Morus alba (cv. Sujanpuri) were raised from nodal explants with axillary buds collected during three different periods of the year. The growth and shoot/root multiplication of the nodal explants collected between November to February and July to October were found to be better than those collected between March to June. In cultures, shoot multiplication was induced by the application of 2.5 mg/l of 6-benzylaminopurine (BAP) and 0.3 mg/l of gibberellic acid (GA 3 ), while rooting by 1.0 mg/l of indolebutyric acid (IBA). Sodium chloride (NaCl) was added to induce salt stress and its concentration was gradually increased from 0.1% (w/v) onwards. The salt tolerance was observed up to 0.4% (w/v) NaCl and 100% mortality of explants was noted above this concentration. The inclusion of Arbuscular Mycorrhizal (AM) fungi and Azotobacter chroococcum to tissue culture of raised saplings during acclimatization enhanced their survival and resulted in a significant increase of plant growth. After the transfer of plants to salt affected wasteland, only NaCl-treated saplings survived, whereas those developed without NaCl resulted in 100% mortality. plying salt (NaCl) stress and if exploiting AM fungi and Azotobacter during hardening could enhance the survival percentage of developed plants on salt affected land. Keywords: in vitro; MATERIALS AND METHODSExplant collection: Growing shoots of Morus alba L. cv. Sujanpuri were collected from one year old mulberry plants cultivated on normal soil (pH = 7.5, EC = 0.110 mmhos/cm) at Micromodel, IIT, Delhi during the following months: A) March to June, B) July to October, C) November to February. Nodal segments with one axillary bud each (1.5 to 2.0 cm) were excised, washed and disinfected first with 0.7% (w/v) bleach solution (sodium hypochloride) for 10 min and with 0.1% aqueous mercuric chloride solution for next 10 minutes and then rinsed 5 to 6 times with sterile distilled water.Shoot multiplication: The Murashige and Skoog's (MS) (1962) medium containing 3% (w/v) sucrose, 2.5 mg/l of BAP and 0.3 mg/l of GA 3 with 1.0% agar and pH 5.8 was used as shoot multiplication medium. For induction of salinity stress, the medium was supplemented with 0.1% NaCl. The surface sterilized explants were inoculated vertically onto the culture medium with one explant per test tube and twenty test tubes were kept for each treatment.Cultures were grown under cool white fluorescent tubes with irradiance of 24 µmol m 2 /s, 16 h photoperiod and at the temperature of 25 ± 1°C. After multiple shoot induction, the NaCl concentration of medium was gradually increased from 0.1 to 0.4% till 100% mortality of explants observed and average shoot length and number of shoots per explant was noted.Root induction: For rhizogenesis, well developed shoots (5.0 cm long) with 2-3 leaves were excised from cultures and cultured on MS supplemented with 1.0 mg/l of IBA, 3.0% sucrose and NaCl (from 0.1 to 0.4%). For root production, shoots were inoculated on medium with the...

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Pot experiments were conducted for the development of salt tolerant Mentha arvensis (Japanese mint, family: Labiatae) saplings involving bioinoculants, namely Arbuscular Mycorrhizal (AM) fungi, Azotobacter and an auxin -Indole Acetic Acid (IAA). The IAA and sodium chloride (NaCl) concentrations were standardized prior to the experiments. The 10-ppm IAA and 0.08% NaCl (w/v) were found to be optimum in combination with AM fungi and Azotobacter to increase all the growth parameters and microbial count in the rhizosphere. For development of salt tolerant saplings, the optimal concentration of IAA, along with AM fungi and Azotobacter in different combinations, was applied in pots. The saplings were irrigated regularly with 0.08% NaCl water. Although plant growth, AM infection percentage, AM spores/100 g soil and Azotobacter cells/g soil were affected by NaCl watering, the inoculation of both bioinoculants significantly enhanced survival percentage of saplings from 10 to 40% under salt stress. Maximum survival (40%) of saplings was found with IAA (10 ppm) + AM fungi + Azotobacter treatment.