effect of liquid media culture systems on yam plant growth (dioscorea alata l. 'pacala duclos')

The culture system type in liquid media influences yam plant growth ('Pacala Duclos' clone). In culture systems with forced renewal of internal atmosphere in culture flasks, Temporary Immersion System (TIS) and Constant Immersion System (CIS) with aeration through continuous bubbling in culture medium, higher results were obtained in morphological and physiological plant indicators in comparison with plants obtained in culture systems with passive renewal of internal atmosphere in culture flasks or Static Liquid System (SLS). In Temporary Immersion System, the best results were obtained after six weeks of culture in relation to total length (20.8 cm), axillary bud number (8.6), fresh weight (2.1 g) and dry weight (0.18 g) per plant, as well as photosynthetic pigment content (chlorophyll a, b, and total), net photosynthesis (15.3 μmol C02.m-2.s-1), total transpiration (5.97 mmol H2O.m-2.s-1), stomatal conductance (457 μmol H2O.m-2.s-1) and leaf starch content (45.77 mg.gMF-1). Reducing sugar in culture medium with Temporary Immersion System was completely depleted, and mineral nutrients of lower contents (phosphorus, nitrogen, magnesium, calcium, iron, and manganese) in culture medium from this culture system could be related with plant growing. The results of this work could contribute to develop protocol for in vitro plant propagation of this yam clone.