Informatics Publishing Limited

A. M. Rao , S. K. Reddy , V. R. M. Rao , J. K. Bhalla

Abstract

Shoot tip explants from three cultivars of Date palm viz. Sukari, Barhee and Kalas were used for callus initiation. They were cultured in MS medium supplemented with 40 mg/l NAA or NOA and 1.5 gm/l charcoal. Cultures were subcultured every week for three months and incubated in dark conditions. The callus was transferred to low auxin media for induction of somatic embryogenesis. The somatic embryos were developed into plantlets in hormone-free medium. The plants were acclimatized in the glass house and finally transferred to the field.

Full Text

     

Subhasish Ghosh ¹, S. Chakraborty ², J. K. Bhalla ³, D. K. Paul ¹, Amitabha Sarkari ¹, P.K. Bishui ¹, S. N. Gupta ¹

Affiliations
1 Geochronology and Isotope Geology Division, Geological Survey of India, Calcutta-700 016, IN
2 Petrology Division, Geological Survey of India, North Eastern Region, Shillong, IN
3 Geochronology and Isotope Geology Division, Geological Survey of India, Calcutta - 700 016, IN

Abstract

Discordant granite plutons at Kyrdem, Nongpoh and South Khasi intrude the basement gneisses and the overlying Shillong Group of metasediments in the Meghalaya Plateau. Porphyritic granitoids ranging in composition from quartz monzonite to granite represent the dominant component in all the three plutons. Common characteristics of these granitoids arc spatial association with hornblende dioritic rocks, dominantly potassic and metaluminous nature. A positive correlation of SiO₂, Na₂O + K₂O, Rb, Rb/Sr and negative correlation of CaO, MgO, FcO(T), Sr, TiO₂ with Differentiation Index in the Kyrdcm pluton point to fractional crystallisation processes. Rb-Sr whole rock isochron data of the plutons yield ages in the range 480-690 Ma wiLh initia1 ⁸⁷Sr/⁸⁶Sr ratios ranging from 0.70948 -0.71482. Absence of post emplacement tcctonolhennal event is suggested by near concordant K-Ar biotite ages.

A protracted thennal event during late Proterozoic-early Palaeozoic (500-700 Ma), possibly related to mantle upwelling, possibly triggered the generation of these granitoids.

Keywords

Geochrmology, Geochemistry, Granitoids, Khasi Hills, Meghalaya.

Full Text