No abstract

Potential of Arbuscular mycorrhizal (AM) fungi in alleviating adverse salt effects on growth was tested in garlic (Allium sativum L.). Towards this objective we analyzed the AM root colonization and the activities of various antioxidant enzymes like peroxidase, catalase, and superoxide dismutase at 0, 100, 200 and 300 mM salinity levels. The activities of all the antioxidant enzymes studied were found to be increased in AM garlic plants. Antioxidant activity was maximum in 100 and 200 mM NaCl (sodium chloride) in AM and non-AM plants. Proline accumulation was induced by salt levels and it was more in leaves as well as roots of AM plants as compared to non-AM plants, this indicating that mycorrhiza reduced salt injury. Growth parameters of garlic plants like leaf area, plant fresh and dry weight and antioxidant enzyme activities were higher at moderate salinity level. This work suggests that the mycorrhiza helps garlic plants to perform better under moderate salinity level by enhancing the antioxidant activity and proline content as compared to non-AM plants.

Gmelina arborea Roxb. is medicinally and economically important tree species were selected for study. An experiment was conducted to determine the influence of arbuscular mycorrhizal (AM) fungus Glomus fasciculatum on salt stress tolerance of tree species Gmelina arborea. Mycorrhizal and nonmycorrhizal seedlings were treated with 100 mM and 200 mM concentration of NaCl. G. fasciculatum treated plant showed increase in fresh and dry weight, greater percentage of mycorrhizal colonization, higher accumulation of proline and chlorophyll content with increasing levels of salinity. G. fasciculatum colonization significantly increased tolerance of salinity, acid phosphatases, and Proline content and also antioxidant enzymes like peroxidase, catalase and superoxide dismutase at all levels of salinity treatments of Gmelina plants in comparison with non-mycorrhizal salinity treated plants. These results demonstrate that AM fungus (G. fasciculatum) is very effective in strengthening the tolerance of Gmelina arborea grown in arid and semi arid areas.

The fungal pathogen causes serious widespread losses to agricultural crops worldwide. Therefore, economy of countries may worsen especially of developing countries. In addition, harmful chemical pesticides which are being used today for increasing crop production creates very serious health hazardous problems to human beings and ecosystem as a whole. The antagonistic potential of Trichoderma species which has been long known to control various soil-borne fungal pathogens in biological way may be utilized. The faster growth rates with which it competes with fungal pathogen mainly brings upon their antagonistic characteristics. An investigation was carried out in laboratory condition towards biological efficacy of T. viride on potato dextrose agar (PDA) medium for the bio-control of soil-borne plant pathogens Sclerotium rolfsii and Macrophomina phaseolina in in-vitro condition. The dual culture technique was followed in which T. viride showed significant antifungal activities towards both the pathogens. T. viride significantly inhibited the mycelial radial growth of S. rolfsii by 75% and M. phaseolina by 71.42%. The results showed variable mycelial growth rate for all fungal isolates which was determined after 6 days of incubation in which T. viride showed minimum of 4.00 days to completely cover the petri-plates and S. rolfsii showed 4.33 days whereas M. phaseolina showed 6.33 days. Thus, T. viride showed encouraging results regarding their biopesticidal and biofungicidal potential against plant pathogens which may be endorsed to substitute harmful chemical supplements that exists in modern day agricultural practices.

Catharanthus roseus L. (Apocynaceae), a valuable medicinal plant with potential therapeutic value was inoculated with AM fungi Glomus fasciculatum under three different phosphate conditions. Catharanthus roseus plants raised in presence of the AM fungi showed increased growth in terms of (shoot length, root length, leaf number, fresh weight and dry weight). Total chlorophyll content and phosphate content of the shoot was found to be significantly higher in AM inoculated plants as compared to non AM Catharanthus plants. The activities of phosphatase enzymes were found to be increased in AM inoculated plants as compared to non AM plants. Root colonization percent was significantly higher in AM inoculated plants at zero and at all three phosphate levels after 60, 90 and 120 days of AM inoculation, but decreased at third phosphate level after 120 days of AM inoculation. The study suggests that Catharanthus roseus is dependent on the mycorrhizal fungi to a large extent for its growth and survival and also shows the potential of AM fungi Glomus fasciculatum in increasing growth and biomass of Catharanthus roseus L.