An effective nutrient medium for asymbiotic seed germination and large-scale in vitro regeneration of Dendrobium hookerianum, a threatened orchid of northeast India

Submergence inhibits photosynthesis by terrestrial wetland plants, but less so in species that possess leaf gas films when submerged. Floodwaters are often supersaturated with dissolved CO2 enabling photosynthesis by submerged terrestrial plants, although rates remain well-below those in air. This important adaptation that enhances survival in submerged conditions is reviewed

Micropropagation of Ilex khasiana, a critically endangered and endemic holly of Northeast India

The paper describes in vitro techniques for mass propagation of IIex khasiana, a rare and critically endangered holly endemic to Khasi Hills Hills of Meghalaya, India. The approach will help conserve I. khasiana and other endangered species

Plantlet regeneration of Pinus kesiya Royle ex Gord. from mature embryos

262-266A high frequency (90.5%) of shoot bud induction was observed in mature zygotic embryos of Pinus kesiya Royle ex Gord. that were pre-cultured in Quoirin and Lepoivre (LP) medium containing 23.15 μM Kn for 4 wk and then transferred to growth regulator-free medium. Multiplication and elongation of the shoot buds resulted in 1/2 LP medium containing 0.5 μM IBA and 4.5 μM BAP or Kn. Rooting was 72.3% in isolated shoots that were treated with 53.76 μMNAA for 24 h and then cultured on water-agar medium. Plantlets were hardened and successfully established on soil collected from pine forests with 70% survival. Biomass of the micropropagated plants was 3.2 times higher than seed-derived plants

<i style="mso-bidi-font-style:normal"><span style="font-size:11.0pt;mso-bidi-font-size:10.0pt;font-family:"Times New Roman"; mso-fareast-font-family:"Times New Roman";mso-bidi-font-family:"Times New Roman"; mso-ansi-language:EN-GB;mso-fareast-language:EN-US;mso-bidi-language:AR-SA" lang="EN-GB">In vitro</span></i><span style="font-size:11.0pt;mso-bidi-font-size: 10.0pt;font-family:"Times New Roman";mso-fareast-font-family:"Times New Roman"; mso-bidi-font-family:"Times New Roman";mso-ansi-language:EN-GB;mso-fareast-language: EN-US;mso-bidi-language:AR-SA" lang="EN-GB"> multiplication of <i style="mso-bidi-font-style: normal">Thunia marshalliana</i> Rcbh. f. through mature seeds and pseudonodes</span>

268-273The present paper describes the germination of mature embryo (~seed), seedling development, and <i style="mso-bidi-font-style: normal">in vitro shoot induction and plant regeneration from pseudonode explants of an endangered ornamental orchid, <i style="mso-bidi-font-style: normal">Thunia marshalliana Rcbh. f. The observations on efficacy of nutrient medium composition on in vitro embryo germination and early seedling development demonstrated that nitrogen in any form induced germination and the presence of both organic and inorganic nitrogen into the medium enhanced both germination and seedling development. The modified MS medium having 10% coconut water was found to be the best for germination. Addition of cytokinin did not favour protocorm formation and seedling development. However, multiple shoots were induced directly from the pseudonode explants cultured on MS medium containing different concentrations of 6-benzyl amino purine (BAP) and kinetin (Kn). Amongst the two cytokinins (BAP & Kn) tested, BAP was more effective for direct shoot induction from the pseudonode explants as compared to Kn. The optimal response was observed at 22.0 µM BAP, which induced 3.67 shoots per explant in 3 wk of culture initiation. These shoots (73%) were rooted on their transfer to MS medium. Both the seedlings and rooted shoots were successfully transplanted to plastic pots filled with cow dung, moss, brick pieces and charcoal mixture in equal ratio. </span

Conservation and management of plant genetic resources of Northeast India

29-34The Northeast India region is rich in biodiversity due to high rainfall and plenty of sunlight coupled with unique bio-geographical positioning. It is known as the ‘Cradle of Flowering Plants’ because of remarkably rich and diverse flora. The valuable plant genetic resources of the region are being lost at an alarming rate due to varied human activities including shifting cultivation which have in turn led to the depletion of forest cover. Therefore, there is an urgent need for conservation, sustainable utilization and management of plant genetic resources of the region so as to meet the growing requirements of food, fodder, fibre, health, water and other needs

Micropropagation of Coptis teeta Wall.–Threatened medicinal plant of Arunachal Pradesh, India

280-282Multiple shoots were produced from axillary buds with rhizome parts from mature plants of Coptis teeta on ½ strength Murashige & Skoog’s (MS) nutrient salts medium containing 4.42 μM benzylamino purine+0.56 μM indole-3-acetic acid. Isolated shoots were rooted on ½ strength MS medium supplemented with 7.35 μM indole-3-butyric acid. Plantlets were also regenerated directly from rhizome segments cultured on Gamborg’s medium containing 2.31 μM kinetin+0.56 μM indole-3-acetic acid. Regenerated plantlets were hardened and established in the glass hous