HOP CALLUS-CULTURE

First information on hop callus formation is referred by Vine, Jones (1969) in cultivation of isolated hop tops. Induction and regeneration of the plant from hop callus derived from the leaf were performed by Motegi (1976). Robins et al. (1985) were dealing with the degrading of alpha-bitter acids in supsension hop culture. Svoboda (1988) describes the callus formation in cultivation of top meristems of hops in dependence on high concentrations of NAA and BA growth regulators in nutrient medium. Hop callus culture (Humulus lupulus L.), the Zlatan variety, as derived from the top meristem, was studied. The variety was marked by an intensive callus growth of light-yellow colour. The medium as described by Murasghige, Skoog (1962), containing 10 muM.l-1 IAA, 8 muM.l-1 of kinetin, 1 muM.l-1 of GA3 and 40 g of glucose per 1 litre. Sterilization was performed in autoclave for 15 minutes at 110 KPa, pH value was adjusted with 0.1 N NaOH to the value 5.7 before autoclaving. Calluses were cultivated in the cultivation room with the temperature of 25 +/- 2-degrees-C at illumination 2,500 lx for 16 hours and 8 hours in the dark. After two-years cultivation the callus was propagated and its growth has been studied. An initial weight of inoculum was ranging from 50 to 500 mg (Tab. I). The weight of calluses was fixed after 28-day cultivation. Overall weight of calluses (H-1) was assessed, weight gain of new-formed as the difference H-1 - H-0 and the ratio of new-formed callus to the initial weight according to the relationship: (H-1 - H-0).100/H-0 where: H-0 and H-1 are initial and final weights of calluses in mg. The values obtained are shown in Tab.I and on Figs 2 and 3. Simultaneously with it, in formed calluses the dry matter was determined in the following way (Tab. I): calluses were placed in weighed driers covered with the lid and for 3 hours were drying uncovered at the temperatures 104 and 105-degrees-C. Then they were dried, covered with the lid, and placed into desiccator to cool. After weighing, water contents were calculated from the difference of weights before and after drying on the basis of formula: % H2O = b.100/a where: a - sample weight before drying (g): b - loss resulting from drying (g). The calus weight after 28 days of cultivation was ranging from 171 to 3,250 mg and weight gain (H-1 - H-0) was fluctuating from 121 to 2,756 mg (Fig. 2). The highest values were obtained in the cultures with high initial weight. The growth intensity was ranging from 242 to 1,328 %. The highest values were achieved in the cultures with the highest starting weighth. i.e. 50 mg, and with their growing weight, the growth intensity was failing (Fig. 3). Average value of dry matter of calluses was 6.84 %, where the lowest value was 5.98 %, and the highest one - 7.82 %. The results obtained are very interesting, that is why our further attention will by paid to the callus cultures of hops.