TRIPLOIDS IN CUCUMBER - I - FACTORS INFLUENCING EMBRYO RESCUE EFFICIENCY

In vitro culture of late heart stage triploid embryos isolated from re ciprocal crosses of tetraploid x diploid of three cucumbers lines (411 , 412, and 413) led to high variation of development, depending on the lines, and cross direction. Five main deficiencies decrease the chanc e of obtaining triploid plants: inability of embryos to germinate, non -rooting plantlets, albinism, mixoploid, and non-survival in the soil. The lowest rate of failure occurred when the tetraploid was the femal e parent. Depending on the line, 11.7-45.8 of embryos obtained in the. 4x x 2x direction developed into plants. Triploid plants did not show visible abnormalities. Flow cytometry analysis of the plant DNA conte nt revealed that normal plants were triploid, while poorly growing and abnormal plants were hexaploid or mixoploid.