Rajmohan, KRamesh, BKAU2019-02-142019-02-141990170292http://krishikosh.egranth.ac.in/handle/1/5810094984PGThe problem of poor ex vitro establishment of jack plantlets was addressed in a study conducted during 1988-90 at the Plant Tissue Culture Laboratory of the Department of Horticulture, College of Agriculture, Vellayani. A reliable protocol could be standardized based on the analysis of the factors influencing plantlet production and their ex vitro establishment and characterization of the morphological, histological and physiological peculiarities of the in vitro raised plantlets. A rooting medium (MS) containing half strength inorganic nutrients (particularly inorganic nitrogen and calcium salt), sucrose 30.0 g/l and agar 6.0 g/l was identified as ideal for the in vitro rooting and ex vitro establishment of jack plantlets. Activated charcoal was not useful for the purpose. Shoots of 3.0 cm length, with three to four leaves, recorded 100.0 percent rooting, 5.5 roots per shoot and good root branching (2.75). Erlenmeyer flasks of 100 or 150ml capacity were the superior culture vessels for in vitro rooting. A light intensity of 50 µE m-2S-2 for 21 days was required during the prior to planting out stage for successful ex vitro establishment. Plantlets of 18 days and above old recorded the maximum survival ex vitro. Sand was identified as the best potting medium. However the moisture level of sand has to be maintained at an optimum of 13.4g/100g of soil. Plastic pot (5.0 x 5.0 x 7.5 cm size with small holes) was found to be superior to the other containers tried. Mist chamber was found to be convenient and successful as a humidity maintenance device for the hardening of the plantlets. Use of antitranspirants was not advantageous for the establishment of the plantlets. Inoculation of the potting medium with the vesicular arbuscular mycorrhiza Glomus fasciculatum and G etunicatum favoured 80.0 to 100.0 percent ex vitro establishment of the plantlets; the plant growth was significantly increased in such cases. Nutrient starter solutions cannot be recommended during the initial period of acclimatization as they reduced the survival of the plantlets. Leaves of the in vitro raised plantlets had improper deposit of epicuticular wax and underdeveloped palisade parenchyma, Spongy parenchyma, mechanical tissues and vascular bundles. The stomatal aperture was comparatively large. The stomata did not close when exposed to stress conditions. The morphological and histological peculiarities caused high rate of water loss (16.0 mg/cm2 in 105 minutes) from the plantlets when planted out and hence necessitated an initial humidity acclimatization. The mean number of stomata per unit area, total chlorophyll chlorophyll a and chlorophyll b contents were less in the in vitro grown leaves. The morphological, histological and physiological characteristics of the plantlets were normalized during the ex vitro establishment, especially as the new leaves were produced.ennullThesis