[en] The cash crops grown in an agro-climatic region are prone to infection by various fungal pathogens. The use of chemical fungicides over the years has resulted in emergence of resistant fungal strains, thereby necessitating the development of effective and environmental friendly alternatives. The natural antagonistic interactions among different microbial populations have been exploited as an eco-friendly approach for controlling fungal pathogens resistant to synthetic chemicals. Morphologically distinct bacterial cultures (150), isolated from rhizospheric soils of wheat, rice, onion and tomato plants were screened for their antifungal potential against seven phytopathogenic fungi prevalent in the State of Punjab (India). The bacterial isolate R2, identified as Bacillus vallismortis, supported more than 50% inhibition of different phytopathogenic fungi (Alternaria alternata, Rhizoctonia oryzae, Fusarium oxysporum, Fusarium moniliforme, Colletotrichum sp, Helminthosporium sp and Magnaporthe grisea) in dual culture plate assay. The thin layer chromatography based bio-autography of acid-precipitated biomolecules (APB) indicated the presence of more than one type of antifungal molecule, as evidenced from zones of inhibition against the respective fungal pathogen. The initial analytical studies indicated the presence of surfactin, iturin A and fengycin-like compounds in APB. The antifungal activity of whole cells and APB of isolate R2 was evaluated by light and scanning electron microscopy. The wheat grains treated with APB and exposed to spores of A. alternata showed resistance to the development of black point disease, thereby indicating the potential application of R2 and its biomolecules at field scale level. (Author)

[en] Application of exogenous ethylene in combination with gibberellic acid (GA₃), kinetin (KIN), and/or CO₂ has been reported to induce germination of lettuce seeds at supraoptimal temperatures. However, it is not clear whether endogenous ethylene also plays a mediatory role when germination under these conditions is induced by treatment regimes that do not include ethylene. Therefore, possible involvement of endogenous ethylene during the relief of thermoinhibition of lettuce (Lactuca sativa L. cv Grand Rapids) seed germination at 32°C was investigated. Combinations of GA₃ (0.5 millimolar), KIN (0.05 millimolar), and CO₂ (10%) were used to induce germination. Little germination occurred in controls or upon treatment with ethylene, KIN, or CO₂. Neither KIN nor CO₂ affected the rate of ethylene production by seeds. Both germination and ethylene production were slightly promoted by GA₃. Treatments with GA₃ + CO₂, GA₃ + KIN, or GA₃ + CO₂ + KIN resulted in approximately 10- to 40-fold increases in ethylene production and 50 to 100% promotion of germination as compared to controls. Initial ethylene evolution from the treated seeds was greater than from the controls and a major surge in ethylene evolution occurred at the time of visible germination. Application of 1 millimolar 2-aminoethoxyvinyl glycine (AVG), an inhibitor of ethylene synthesis, in combination with any of above three treatments inhibited the ethylene production to below control levels. This was accompanied by a marked decline in germination percentage. Germination was also inhibited by 2,5-norbornadiene (0.25-2 milliliters per liter), a competitive inhibitor of ethylene action. Application of exogenous ethylene (1-100 microliters per liter) overcame the inhibitory effects of AVG and 2,5-norbornadiene on germination. The results demonstrate that endogenous ethylene synthesis and action are essential for the alleviation of thermoinhibition of lettuce seeds by combinations of GA₃, KIN, and CO₂. It also appears that these treatment combinations do not act exclusively via promotion of ethylene evolution as the application of exogenous ethylene alone did not promote germination. (author)

[en] Radiometric dating of movements along the MCT (Vaikrita Thrust), two local but deep seated thrust and the Sumdoh Fault Zone bordering the Kinnar Kailas Granite in the Baspa and Satluj valleys, NE Himachal Himalaya, has been attempted for the first time by fission track method. Garnet and apatite fission track ages suggest the age of the latest phase of movements around 14 and 7 m.y. respectively along the MCT and Sumdoh Fault. The vertical uplift rates along them were 1.1mm/year from 14 to 7 m.y. and 0.6 mm/year from 7 m.y. to recent geologic past respectively, as against the value 0.036 mm/year during the period from 210 to 17 m.y. in the undisturbed area. (author)

[en] The studies on thermal annealing of tracks stored in different minerals are carried out by track density as well as track length measurements. The average range of fission fragment in the minerals has been determined. It has been observed that the annealing of the tracks depend on their initial length and therefore on the charge of the incident ions. Thermal effect on fission fragments reveal that the shrinkage in range is accompanied by the reduction in number of tracks per unit area. The complete annealing data (i.e. experimental and geological annealing temperatures required to cause different degrees of track annihilation in different annealing areas, activation energy spectra etc.) of the ten minerals have been incorporated in the present report. The calibration curves and annealing vs optimum etch-time graphs have been constructed for their use in fission track geochronology. The annealing characteristics of the minerals coupled with their fission track ages help in the evaluation of the cooling/thermal history and tectonic uplifts of the parent rocks. The versatile applications of track annealing phenomena are briefly discussed. (author)

[en] The radiometric age data obtained by different dating methods have been interpreted in terms of possible orogenic activities prevailing in the Himalaya. In general, the age data confirm four main events, the Precambrian, the Late Precambrian-Cambrian Assyntian (Caledonian), the Late Palaeozoic-Hercynian and the Late Cretaceous-Tertiary Himalayan orogeny. The mineral dates are particularly significant in delineating different phases of the last i.e. the Himalayan orogeny which indicates main activity of the young Himalayan metamorphism around 70 to 50 Ma and followed by a momentous phase of major uplift during 25 to 10 Ma, which was responsible for the rise of the deeper part of the Himalaya into great folds and thrust slices and the formation of nappe structures. (author)

[en] Different terrestrial rocks and minerals are found to have permanent records of the radiation damages which are due to spontaneous decay of uranium and hence the tracks left by spontaneous fission of traces of uranium in many minerals are clues of the 'mineral's age'. The basic principles of the F-T dating technique, its applications and some of the results achieved are reviewed. (auth.)

[en] Variation of fission track density with etching time has been analysed to standardize the etching conditions. The relations between the etching parameters (i.e., temperature, concentration and time) have been established. The differences in unheated samples and samples heated for different times at a constant temperature have been studied. Graphs of thermal annealing vs. optimum etching time and of density reduction vs. length shrinkage have been constructed for applications in fission track geochronology. (Auth.)

[en] Variation of density with etching time at different annealing temperatures has been studied. It has been found that a plot of annealing vs. etching time is a straight line. The relation between density reduction and length shrinkage is not exactly linear. (author)

[en] The study of the distribution and abundance of uranium in minerals and whole rocks is discussed in connection with fission-track age determination and annealing studies. The report compiles the average values of the mean combined range of two fission fragments which are produced by the thermal neutron bombardment of minerals and the closing temperatures of the fission-track system for solid state nuclear track detectors, worked out so far in fission-track geochronology, and discusses their applications. (U.K.)

[en] Fission track (F-T) etching conditions, dating and U-concentrations of glauconite, an authigenic sedimentary mineral, are presented here. A mixture of 98% sulphuric acid, 48% hydrofluoric acid and distilled water in the proportion 1:2:4 was used to etch fission tracks in glauconite. The developed tracks have a conical needle shape similar to those in apatite but of shorter length. Optimum etch time has been found to be 35 min using the above etchant at room temperature (25degC). F-T ages of 87 and 680 m.y. determined for separated glauconite crystals respectively from Lameta beds of Jabalpur and green sandstone bed of Newari, District Mirzapur, are in good agreement with geological ages assigned to these strata. U-concentrations in the samples are obtained as 125 and 33 ppb respectively. (author)