A procedure has been developed for the clonal propagation of Picrorhiza kurroa Royle ex Benth. through shoot tip culture. Murashige and Skoog's medium (1962) supplemented with kinetin (3.0 to 5.0 mg/l) supported rapid proliferation of multiple shoots from the explants. Addition of indole-3-acetic acid (1.0 mg/l) to the kinetin containing medium showed marked improvement in the growth of regenerated shoots. However, presence of IAA in the medium did not alter the frequency of shoot multiplication. Rooting was readily achieved upon transferring shoots onto MS medium containing ∝-naphthaleneacetic acid (1.0 mg/l). Plantlets were successfully transferred to soil.

Allelopathic effects of Cyperus rotundus on banana 'Grande Naine' were studied in vitro as well as ex vitro. To study the allelopathic effects in vitro, the Cyperus extract was added to the multiplication medium during preparation before adjusting the pH. Of the four concentrations, 0.2 and 0.6% decreased the shoot multiplication and shoot length but 1 and 2% extract completely inhibited the shoot multiplication but induced rooting in 50 and 28% shoots, respectively. For the ex vitro studies, the Cyperus extract was added to the hydroponic medium during the hardening of in vitro raised banana plantlets. The extract of 1 and 2% concentrations decreased the shoot and root length, number of leaves and new roots, fresh weight, total chlorophyll and protein. The fluorescence intensity ratio was successively increased resulting in decreased photosynthesis.

A procedure has been established for high frequenc}', long-term plant regeneration from leaf sheathderived callus cultures of Gitronella Java, variety 'jorhat'. A total of 600 plants were suecessfully transferred to the glass house, and subsequently 500 of tbese were shifted to the field in fwo batches of 250 plants each. From amongst 230 plants of the first batch, on which data %vere recorded, extensive somaclonal variations were observed for seven agronomic traits, viz,, herbage yield, tiller number, diameter of the bush, length and area of the longest leaf, fresh and dry weight ratio and oil content. In addition, variations were also recorded for six major constituents of the essential oil pool, i.e., eitronellal, citronellol, geramol, citronellyl acetate, geranyl acetate and elemol, Gorrelation analysis between agronomic traits revealed a signifieant negative correlation between oil content and herbage yield. However, plants with higher herbage yield (> 3 fold) and oil content (> 1.5-2.0 fold) than the parent variety could be selected from amongst the variants. Furthermore, plants could be recovered with itnproved oil quality, possessing higher levels (> 1,5 fold) of desirable constituents of the oil like eitronellal, citronellol, geraniol and geranyl acetate together with a reduced level (> 5 fold) of elemol which is an undesirable component of the citronella oil. Out of the 19 selected somaclones that were evaluated in a replicated trial with the donor parent as control, 5 lines have been further plaeed under multilocational trials for stability assessment. The scope of somaclonal variation is discussed in the improvement of \'egeta-'' CIMAP Publication NUITIIX'I' 75S, lively propa,gated aromatic grasses that have a narrow genetic base.

An effort has been made to propagate Dendrocalamus strictus Nees using nodal explants from mature plants. The explants, after surface sterilization, were inoculated on solidified MS basal medium with 2 mg/l BAP. The buds, which started growing, were transferred to solidified MS basal medium with 4 mg/l BAP and 15 mg/l AdS to achieve about three fold multiplication. Single shoots or 2-shoot clusters did not survive and therefore all the experiments were conducted with a cluster of minimum 3-shoots. The rooting was found difficult. Three hormones viz. IAA, IBA and NAA with a concentration of 1, 3 and 5 mg/l were used in various combinations for rooting. Out of the total 9 treatments, only 20% rooting was found only in one treatment, namely in the medium with 5 mg/l indole butyric acid (IBA).

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