The objectives were to compare the salt tolerance levels in the parental rice cultivar, Dongjinbyeo, and induced mutagenesis derived its lines for plant height, MDA, ATPase, POD, and 2-dimensional protein electrophoresis pattern in NaCl-containing hydroponic nutrient solutions. Rice plants isolated from a population of rice (Oryza sativa L. cv. Dongjinbyeo) mutation lines, which were generated in combination with in vitro selection and gamma-ray, exhibited salt tolerance. Line No. 18 had the longest plant, whereas NaCl-sensitive line (No. 25) had the shortest plant. The parent, and the sensitive line showed severe damage from salt stress. Tolerant lines (No. 18, 50) had a lower malonaldehyde (MDA) content than the sensitive one (Dongjinbyeo, No. 25) during salt stress. Several proteins showed significant quantitative variation through 2DE; phosphoribulokinase, peroxidase, oxygen evolving enhancer 1 and the $H^+-ATPase$, which are known to be involved in salt tolerance. The effect of salt on peroxidase and $H^+-ATPase$ activity in the seedlings of two groups with contrasting genotypes of rice was studied. A greater activity was recorded in the tolerant lines as compared to the sensitive ones (P<0.05, Duncan's test). The results indicate that salt tolerant lines expressed more salt stress-inducible proteins associated with salt tolerance than the sensitive lines during salt stress.

Zygotic embryos were excised from immature and mature seeds of the Himalayan yew, Taxus wallichiana. The embryos germinated precociously when kept in darkness for 5 weeks and developed into full seedlings within 10-12 weeks. The highest rate of embryo germination ($81\%$) was obtained in modified Lloyd & McCown' s woody plant medium containing macro and micronutrients at half strength supplemented with $1\%$ activated charcoal, which supported both the best embryonic growth ($43\%$) and seedling development ($32\%$). However, the supplementation of basal media with kinetin, thidiazuron, 6-benzyl aminopurine or $GA_3$ had no effect on the germination of the embryos. The embryos derived from immature seeds germinated but the frequency of embryonic growth was better in mature seeds. Stratification of seeds effected precocious germination of embryos. Seeds kept at $4^{\circ}C$ for 1 week germinated earlier and at a higher frequency irrespective of the stage of seed maturity, while the germination rate declined with prolonged cold treatment for 1 month at that same temperature. Analysis of taxanes in germinating seedlings revealed that root tissues contained high levels of taxol, 10-deacetyl-baccatin ill and baccatin ill as compared to shoots. Thus embryo culture technique appears to overcome the lengthy dormancy requirement of T. wallichiana seeds.

Protocol was established for production of virus free healthy seeds using meristem ($0.3-0.5\;\cal{mm}$ in size) culture and field management under net house condition in tomato. The isolated meristem was found well established in MS liquid medium containing $0.1\;\cal{mg}\;1^{-1}\;of\;GA_3$. For shoot and root development either from primary meristem or from nodal segment of meristem derived plants, semisolid MS medium having $0.5\;\cal{mg}\;1^{-1}$ of IBA was found most effective. The elimination of the studied viruses (ToMV, CMV, ToLCV) in meristem-derived plants was confirmed by DAS-ELISA test. For field management of the virus eradicated meristem-derived plants, use of net house was found very effective measures to check viral vector visit and eventually infection. The meristem-derived plants were vigor and high yielder than the native seed derived plants and produced healthy seeds. Due to stop vector visit, no viral symptoms were observed in both $R_1\;and\;R_2$ plants cultivated in net house condition. Starting of viral infestation was observed in $R_2$ generation when they were planted in open house condition without control of vector visit. Therefore, for management of viral diseases, use of virus free meristem derived plantlets and their subsequent cultivation in soil under net house condition without using any vector killing insecticide can be recommended for producing healthy seeds in tomato. The developed protocol for environmentally healthy tomato seed production in Bangladesh may be used in the countries having similar tropical like environment conducive for viral vector visit.

Partial desiccation of embryogenic calli cultures or somatic embryos leads to different physiological changes and maturation of somatic embryos, leading to improved plant regeneration. Embryogenic calli was induced from immature inflorescence segments and young leaf rolls of sugarcane (Saccharum officinarum hybrids CoC-671) on Murashige and Skoog's basal medium enriched with different concentrations of 2,4-D ($1-4\;\cal{mg/l}$), L-glutamine ($100\cal{mg/l}$), malt extract ($100\cal{mg/l}$), casein hydrolysate ($1000\;\cal{mg/l}$) and coconut milk ($5\%$) and solidified with $0.2\%$ gel rite. The embryogenic calli were subjected to desiccation for 1-8 h. Desiccation of the calli for 6-7 h resulted in enhancement of plant regeneration frequency ($83-96\%$) as compared to control ($12\%$). Plantlets exhibited vigorous growth to maturity in the greenhouse. Partial desiccation of embryogenic calli offers as a simple method for improving plant regeneration frequency in sugarcane.

We studied the effect of genotype, explant, age of explant, medium (plant growth regulators and gelling agents), and standardized an efficient regeneration protocol for inbred lines of Chinese cabbage (Brassica rapa ssp. pekinensis). Of the different concentrations of NAA and BA tested, the combination of $5\;\cal{mg/L}\;BA\;and\;0.5\;\cal{mg/L}$ NAA gave the highest frequency of shoot regeneration. The cotyledonary explants had more shoot regeneration frequency ($\ge40\%$) than the hypocotyl ex-plants. Besides, the cotyledonary explants, excised from the 4-day old seedlings, showed higher shoot regene-ration ($56.7\%$). Of the three gelling agents and their concentrations used, 16 g/L agar was found to be the best for shoot regeneration. Shoot regeneration frequency in-creased significantly by supplementing the medium with $4\;\cal{mg/L}\;of\;AgNO_3$ MS medium devoid of NAA showed higher frequency of rooting in the regenerated shoots than the ones supplemented with NAA. Our improved regeneration protocol will be especially useful for the genetic transformation of Chinese cabbage inbred lines to develop transgenic hybrids.

The bulb scales and shoot sections ($7\;\cal{mm}\;\times\;15\;\cal{mm}$) of Lilium oriental hybrid 'Casablanca' were cultured to compare bulblet growth in vitro. Shoots were induced from in vitro grown bulbscales on MS medium with $1.0\;\cal{mg/L}\;BA,\;0.5\;\cal{mg/L}$ IAA, and 30 g/L sucrose. The regenerated shoots were cut into shoot sections, and cultured on MS medium with $2.0\;\cal{mg/L}\;BA,\;0.5\;\cal{mg/L}$ IAA and 30 g/L sucrose for shoot proliferation. Culture of shoot sections stimulated bulblet growth significantly than the bulb scales on MS medium with 60 g/L sucrose. However, the bulblets from shoot sections did not reach ideal size to produce stems with several leaves. Therefore, liquid medium was added into the same vessels to stimulate bulblet growth further. After shoot sections were cultured on MS medium with 60 g/L sucrose and 2 g/L activated charcoal for two months in dark, $20\;\cal{ml}$ liquid media containing various concentrations of sucrose and MS salts were added. Two months later, the added liquid medium stimulated bulblet growth remarkably as compared to bulblets grown without added liquid medium. The added $25\;\cal{ml}$ liquid medium containing 120 g/L sucrose and double strength of MS salts were the most effective for growth of in vitro bulblets. More than $94\%$ bulblets produced by this method sprouted stems with several leaves after cold treatment at $5^{\circ}C$ for three months.

In vitro cultures of watermelon were treated with antimitotic agent colchicine to induce ploidy alterations, particularly the induction of tetraploids. Explants cotyledon, embryonic end of seed, transverse sections of epicotyl and hypocotyl were cultured on MS media supplemented with BA ($1{\mu}M$) and colchicine ($0.01\%,\;0.05\%\;and\;0.1\%$). Explants were subcultured on colchicine free media after 4 and 7 days. Colchicine had negative effect on in vitro regeneration but this exhibited explants related response. However, hypocotyl section of seedlings induced maximum callus on $0.01\%$ colchicine. Shoot proliferation was more in cotyledon explants cultured on colchicine ($0.01\%$) for four days. Maximum root induction and root number were recorded in embryonic end explants. Overall, cotyledon and embryonic end explants, and low colchicine concentration ($0.01\%$) was found optimal in watermelon regeneration.

Plant regeneration depending on explant type was inves-tigated with cotyledon, hypocotyl, and leaf explants of garland chrysanthemum (Chrysanthemum coronarium L.) cultured on MS basal medium supplemented with various concentrations of SAP and NAA combination. Among the three different types of explants, hypocotyl explants grown on MS medium containing $1.0{\mu}M\;NAA,\;1.0{\mu}M\;BA\;and\;6{\mu}M\;AgNO_3$ produced the highest adventitious shoots (4.67 per explant). Hypocotyl explants not only produced more vigorous shoots, which regenerated aster than the cotyledon and leaf explants. An efficient root formation was observed in MS medium containing $3\%$sucrose. The concentration of NAA did not show significant effects on root formation. Results from this experiment suggested that hypocotyl explants were efficient for the regeneration of garland chrysanthemum.

The present study describes the ameliorating effect of $Ca^{++}\;on\;Cd^{++}$ toxicity on the germination, early growth of mungbean seedlings, nitrogen assimilation enzyme. s-nitrate reductase (NR), nitrite reductase (NIR), anti-oxidant enzymes (POD, CAT and SOD) and on the accumulation of hydrogen peroxide and sulphydryls. $Cd^{++}$ inhibited seed germination and root and shoot length of seedlings. While NR activity was down- regulated, the activities of NIR, POD and SOD were up- regulated with $Cd^{++}$ treatment. $Cd^{++}$ treatment also increased the accumulation of sulphydryls and peroxides, which is reflective of increased thiol rich proteins and oxidative stress. $Ca^{++}$ reversed the toxic effects of $Cd^{++}$ on germination and on early growth of seedlings as well as on the enzyme activities, which were in turn differentially inhibited with a combined treatment with calcium specific chelator EGTA. The results indicate that the external application of $Ca^{++}$ may increase the tolerance capacity of plants to environmental pollutants by both up and down regulating metabolic activities. Abbreviations: $Cd^{++}= cadmium,\;Ca^{++} = calcium$, NR= nitrate reductase, NIR=nitrite reductase, POD = peroxidse, SOD= superoxide dismutase, CAT= catalase, EGTA= ethylene glycol-bis( $\beta-aminoethyl ether$)-N,N,N,N-tetraacetic acid.

Cell growth and ginseng saponin production by large-scale suspension (bioreactor) cultures of Panax ginseng were investigated under various inoculum sizes. Cell growth was low at an inoculum size of 40 g FW/L, and the maximum cell growth was obtained with increasing inoculum size up to 100 g FW/L. The cell density of 333 g FW/L and 12.7 g DW/L was obtained at inoculum size of 100 g FW/L after 30 days of cultivation. Maximum saponin production of $4.40\;\cal{mg/g}$ DW was achieved at 60 g FW/L of inoculum size. Thus, inoculum size 60 g FW/L was suitable for optimum biomass accumulation as well as saponin production during bioreactor cultivation of ginseng suspension cells.