| Tetraploid regenerants occurred when melon (Cucumis melo L.) cotyledons were cultured on 10 ;Adventitious shoots of melon were induced when culturing a variety of seed explants from fruit of the breeding line, 'Miniloup,' 10 through 34 days after pollination. Tetraploid regenerants were formed most readily from cotyledon explants from fruit 18 and 22 days after pollination. Tissue taken from the apical node of the same seeds produced little or no tetraploid regenerants. More mature cotyledons of 'Miniloup' also produced fewer tetraploid regenerants. Proximal sections from immature cotyledons of three genotypes ('Miniloup', 'L-14', 'B-line') produced more tetraploids then mature cotyledons. Proximal cotyledon sections of immature cotyledons produced more tetraploid regenerants than distal sections in two genotypes, 'L-14' and 'Miniloup'. Whole immature cotyledons also produced more tetraploids then whole mature cotyledons of 'L-14' genotype.;Triploid germplasm of melon was synthesized, and fruit and fertility characters were assessed. Under greenhouse conditions triploid 'Miniloup' produced fruit with many sterile seed. A second genotype derived from a cross between tetraploid 'Miniloup' and 'Mainstream', an unrelated diploid parent, had increased fruit size and decreased seed number. In the field, fruit size and seed number of both triploid genotypes increased, but a higher percentage of seeds were sterile. Diploid parents were significant in determining sugar content of triploid genotypes. Triploid genotypes derived from a hybrid tetraploid, 'L-14 x B', were partially fertile. |
