Standardization of embryo rescue technique and bio-hardening of grape hybrids (Vitis vinifera L.) using Arbuscular mycorrhizal fungi (AMF) under sub-tropical conditions

In-ovulo embryo rescue in grape breeding programme assures breeding efficiency by curtailing 6 to 8 years in the development of seedless grape cultivars. Effect of different growth regulators, culture media, ovule age, cultivars and mycorrhizal strains on successful in-ovulo embryo rescue were studied in this experiment. With respect to mean ovule age (days after pollination), maximum ovule-embryo growth (2.13 mm2) were obtained when ovules were cultured at 24 days after pollination (DAP) but maximum germination (12.67 %) was obtained when ovules were cultured at 28 DAP. The concentration of IAA (4 mg) + GA3 (0.5 mg) proved to be most effective for germination (13.84 %). Among various media used for culturing ovules on modified MS medium (1/2 macro + 1/1 micro) required minimum days to germinate (96.67) and registered highest germination (13.75 %). Chilling treatment was proved to be one of the important factors for embryo maturation and 60 d of chilling treatment at 4 °C improved embryo germination. With respect to the effect of different growth regulators on various rooting and shooting parameters IBA (1.0 mg·L-1) and NAA (1.5 mg·L-1) were found superior. While comparing different hardening strategies, a glass jar with polypropylene cap (GPP) was found to be most effective as far as hardening success (66.67 %) was concerned. One of the serious impediments in the success of in vitro rescued plantlets is very high field mortality, field survival of rescued plantlets can be effectively increased by using different mycorrhizal strains (AMF) as bio-hardening agents. Among the various strains used for hardening of rescued plantlets T3 inoculated plantlets registered highest survival percent (88.00)

Magneto-transport characteristics of La1.4Ca1.6Mn2O7 thin film deposited by spray pyrolysis

Polycrystalline thin films of double layer manganite La_1.4Ca_1.6Mn_2O_7 (DLCMO) have been deposited by nebulized spray pyrolysis on single crystal LaAlO_3 substrates. These single phase films having grain size in the range 70-100 nm exhibit ferromagnetic transition at T_C ~ 107K. The short range ferromagnetic ordering due to in plane spin coherence is evidenced to occur at a higher temperature around 225 K. Insulator/semiconductor to metal transition occurs at a lower temperature T_P ~ 55K. The transport mechanism above T_C is of Mott`s variable range hopping type. Below T_C the current-voltage characteristics show non-linear behaviour that becomes stronger with decreasing temperature. At low temperatures below T_CA ~ 30K a magnetically frustrated spin canted state is observed. The DLCMO films exhibit resonable low field magnetoresistance and at 77K the magnetoresistance ratio is ~ 5% at 0.6 kOe and \~ 13% at 3 kOe.Comment: 14 pages, 7 figure