Seedless x seedless grape progeny: Technique, results and perspectives

Recent refinements in the in vitro embryo rescue technique employed to raise progenies from abortive ovules of seedless x seedless cultivars include addition of 0.2 ppm NAA (naphtaleneacetic acid) to the medium, inducing highly improved root systems and faster plant development. Selling seedless Vitis vinifera yielded seedless progeny only. Open pollinated Perlette and Flame Seedless gave rise to a high percentage (75 and 87%, respectively) of seedless progeny. Progeny from various crosses between seedless cultivars segregated into 65 normal seeded and 204 seedless. From the totality of 204 seedless progeny 192 bore fruit with very slight seed traces. Progeny from crosses between seeded and seedless segregated only 7.5-8% individuals with comparably slight seed traces, amounting to 1/3 of the progeny rated as seedless. Fresh weight determinations of aborted seeds per berry showed a pronouncedly lower weight in progenies from seedless x seedless crosses. Reduction in average berry size in the seedless fraction of seedless x seedless progenies compared to midparent values was of a similar order of magnitude as that obtained in seedless progeny derived from seeded x seedless crosses