The effect of medium composition on ovary-slice culture and ovule culture in intraspecific Tulipa gesneriana crosses

The effect of several media components on the germination percentage of ovu les in intraspecific T. gesneriana L. crosses was studied by using two embr yo rescue techniques, viz. ovary-slice culture followed by ovule culture an d direct ovule culture. The addition of 9% sucrose to medium for ovary-slic e culture, started at 3 or at 5 weeks after pollination (WAP), significantl y improved the germination percentage as compared to 5% sucrose. The germin ation percentage did not differ between both sucrose concentrations (3% and 5%) used in ovule culture started 4 weeks later with ovules excised from t he ovary-slices (at 9 WAP). Similar germination percentages were obtained w ith media containing the full or half of the concentrations of micronutrien ts and macronutrients of the MS-medium during ovary-slice culture and ovule culture. For direct ovule culture, started at 4, at 6, and at 8 WAP, the g ermination percentages did not differ between ovules cultured on media with 3%, 6% or 9% sucrose. The addition of the cytokinin BAP (0.01 or 0.1 mg l( -1)) had no effect on the germination percentage. The use of liquid-shaken culture resulted in germination percentages which were similar to those on agar-solidified media. Analysis of the carbohydrate concentration of the me dia revealed that, in both media for ovary-slice culture and for ovule cult ure, ultimately all sucrose is converted into glucose and fructose. The tot al concentration of carbohydrates decreased with 19%-48% in the media for o vary-slice culture, whereas the total concentration of carbohydrates did no t decrease remarkably in media for ovule culture.