STUDIES OF IN-VIVO AND IN-VITRO GERMINATION ABILITY OF DRAGON FRUIT (Hylocereus undatus)

Dragon fruit (Hylocereus undatus) is a well-popularized fruit species incountries like Thailand, China and have a great potential for cultivation insemi-arid regions of Sri Lanka. Plant propagation studies have not beencarried out in Sri Lanka, and hence objective of this research was to study thein-vivo and in-vitro germination of Dragon fruit seeds and to select a suitablemedia for in-vitro establishment. Wet filter papers, wet sand, and wet coirdust were used to study the in-vivo germination and Hormone free, MSmedium, Anderson's Rhododendron medium, and McCown Woody Plantmedium incorporated with 1 g/l of activated charcoal was used to study invitrogermination. In-vitro germination percentage was higher (lOa % inAnderson, 98.5 % in MS, and 96 % in WP) when compared to seedsgerminated in in-vivo conditions (50 %in Filter paper method, 45 % in Sand,and 35 % in Coir dust). Seedlings germinated in in-vitro conditions showedhealthy vigorous growth and 15, 14, and 11 mm seedling heights wereobserved with fully opened cotyledons at the end of second week inAnderson, MS, and WP medium respectively. Though similar plant heights(l5±2 mm) were observed, appearance of the seedlings was very weak, andcotyledons had not fully opened under in-vivo conditions. In both in-vivo andin-vitro conditions root system development was similar and root formationwas observed within 6 days with 4±2 mm root length. Germination, plantheight, and appearance of plants were best in Anderson medium. Resultsrevealed that seeds could be successfully germinated in in-vitro conditionsusing Anderson medium supplemented with 1 mg/l activated charcoal as theestablishment medium

IN-VITRO CALLUS FORMATION OF RED SANDALWOOD (Pterocarpus santalinus L.) AS AFFECTED BY EXPLANT TYPE AND DIFFERENT LEVELS OF 2,4-D AND BAP

Pterocarpus santalinus is a valuable medicinal plant, now included in red listof endangered plants under IUCN guidelines. Distribution of this plant in SriLanka is very limited and the local demand for ayurvedic purposes is stillunreached. As conventional propagation techniques are not satisfactory,possibilities in in-vitro techniques seem to be promising, and callus culture isone aspect that has to be studied. Leaf parts, cotyledon parts, root segments,inter-nodal segments, and nodal segments from in-vitro seedlings were usedas explants. 2,4-D and BAP were used separately in six differentconcentrations (1 mg/l - 6 mg/l) for callus initiation Full strength MS medium(Murashige and Skoog, 1962) was used with 30 g/l of sucrose and 8 g/l agaras the culture medium. Callus formation could be observed in every explant.However, large clumps of creamy white callus were obtained from nodalsegments. Callus formation in root segments was very poor and showedbrown color. In nodal segments, callus formation was started within twoweeks and large clumps of callus were observed while slight swellin~occurring on root segments, leaf parts and in cotyledon parts at the end of 41week. Callus formation was best when the culture medium was supplementedwith 3 mg/l of BAP. Though callus formation could be observed in 2,4-D,amount of callus formed was poor. Present studies revealed that MS mediumsupplemented with 3 mg/l BAP is ideal for callus induction in Pterocarpussantalinus and possibility of using nodal segments as initial explants