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ThesisItem Open Access Standardisation of in vitro techniques for rooting,hardening and micrografting in cocoa (Theobroma cacao L.)(Department of Plant Breeding and Genetics, College of Horticulture, Vellanikkara, 1997) Bindu, M R; KAU; Mallika, V KInvestigations on 'Standardisation of in vitro techniques for rooting, hardening and micrografting in cocoa (Theobroma cacao L.)' were carried out at the Department of Plant Breeding and Genetics, College of Horticulture, Vellanikkara utilising the existing facilities of the Plant Tissue Culture Lahoratory of the Department of Plantation Crops and Spices during the period from 1993-1996. Studies were conducted to identify the best rooting protocol and also to refine the technique of micrografting. The nodal segments taken from the field were pretreated with Bavistin (0. 1 %) for half an hour and then surface sterilized in chlorine water for four minutes. The explants were then cultured in the medium, WPM + 2ip 5 + AgNO3 5 + CCC 0.75 + AdSO4 + PG 200 mg l-1 and incubated at 28 + 2oC under 4000 lux light intensity for shoot bud release. For getting sufficient number of elongated shoots, subculturing was done in WPM supplemented with 0.5 % activated charcoal and 200 mg l-1 streptomycin sulphate. Observations of three different genotypes revealed that they responded differently to in vitro contidition and the genotype S 44.1 exhibited a very good growth. Rooting was very poor under In vitro condition and was completely absent under ex vitro condition. Among the different basal media for in vitro rooting, 1/2 MS supplemented with activated charcoal was the best. Maximum rooting was obtained when the shoots were pretreated in IBA 5000 mg l-1 for 3 seconds followed by culturing in the basal medium. Optimum concentration of sucrose for rooting was 3 per cent and that of agar was 0.6 per cent. For rooting, the cultures should be kept at a temperature of 28 + 20 C under dark condition. The genotypes differed in their response to rooting. Among the three genotypes - S 44.1, G VI 67 and G IV 4.1 tested, S 44.1 recorded better rooting. The rooted shoots should be potted in a medium containing a mixture of soilrite and potting mixture in equal proportion for establishment. The plantlets should be covered with polybags for 2-3 weeks and then exposed to ambient condi- tions periodically for hardening. Plantlet survival rate decreased up to the second month of planting out and after that it became static. In vitro micrografting and ex vito micrografting were possible in cocoa. The best rootstock for in vitro micrografting was axenic seedlings cultured in half MS liquid medium devoid of sucrose. These seedlings were ready for grafting in two weeks when raised under high light intensity (4000 lux) and high temperature (28 + 2°C). In vitro shoots from nodal segments were found to be a very good scion material for grafting. Among the different grafting techniqes, side grafting was the most ideal one. Success was the highest when scions with two or more hardened leaves were grafted 4 cm below the cotyledons in 4-5 weeks old axenic seedlings. Anatomical studies revealed that the graft union was complete in about a month. Grafted seedlings showed profuse growth after planting out. Ex vitro micrografting recorded lower percentage of success than in vitro micrografting. Older plants with a few hardened leaves were the most ideal root- stock and the scions should have at least one hardened leaf. Rapid and extensive scion elongation was observed in ex vitro micrografting. The most significant achievement of the present investigation was the standardisation of the technique of in vitro micrografting by which the rooting problem can be surmounted to a great extent.ThesisItem Open Access Induction of genetic variability in kacholam(Kaempferia Galanga L.)(Department of Plant Breeding and Genetics, College of Horticulture, Vellanikkara, 1997) Kanakamany, M T; KAU; Namboodiri, K M NThe present study "Induction of genetic variability in kacholam, Kaempferia galanga L." was undertaken in the Department of Plant Breeding and Genetics, College of Horticulture, Vellanikkara, during 1992-95. Rhizomes of Kaempferia galanga cv. Vellanikkara local were treated with eight doses of gamma rays (2.5,5.0,7.5, 10.0, 12.5, 15.0, 17.5 and 20.0 Gy) and six concentrations of EMS (0.25,0.50,0.75, 1.0, 1.25 and 1.50%) and MV1, MV2 and MV3 generations were evaluated. LD50 of gamma rays was 20.0 Gy and that of EMS 1.5 per cent. The highest values for yield and yield attributing characters were obtained for 7.5 Gy gamma rays and 0.75 per cent EMS. Gamma rays at 15.0 Gy and EMS at one per cent were most effective in inducing variability for rhizome yield and yield attributes. High estimates of heritability (broad sense) coupled with high genetic advance was observed for number of leaves and rhizome number and direct selection for improvement of these traits will be effective. Correlation coefficient between yield and its components indicated significant positive association of yield with number of leaves, tillers, leaf length, plant spread and rhizome number in the untreated control. Mutagenic treatments induced alterations in the association between rhizome yield and components. Path coefficient analysis of important yield attributes indicated that alterations in plant architecture for higher yield is possible with 7.5 Gy Gamma rays. Change in plant architecture so as to improve the yield is rather difficult in EMS. High frequency of positive variants at lower doses and high frequency of negative variants at higher doses were observed. Mutant characters present in MV 2 were not completely expressed in all MV3 plants. In vitro studies revealed that axillary bud explants have the potential to induce multiple shoots as well as roots in Murashige Skoog (MS) medium supplemented with boric acid and sucrose. Different pollination techniques failed to induce seed set in kacholam.