Morphological Changes in Peach Seedlings Following After-Ripening Treatments of the Seeds

Abstract

1. More than 10,000 peach seeds, involving nineteen varieties and twelve sources, were after-ripened at 34⚬-36⚬ F. for weekly intervals ranging from 1 to 12 weeks, and then germinated and grown to seedling size at 68⚬ F. 2. Some of the plants which developed were dwarfed, with anomalous leaves, resembling plants grown from excised embryos of non-after-ripened seeds. Such anomalous plants were most frequent among samplings which were after-ripened for the shortest period of time; they decreased progressively as the after-ripening period lengthened, until all seedlings were "normal." 3. The frequency of anomalous plants was higher from non-germinating, excised seeds than from germinating, non-excised seeds following the same length of after-ripening. 4. The frequency of anomalous plants varied with the variety. 5. Anomalous forms are not the result of photoperiod alone, inasmuch as both normal and dwarfed seedlings developed from seeds planted the same day. 6. Of two lots of pits from California, some were germinating and some not, when received. Of the germinating seeds, all developed into normal seedlings; only a few of the non-germinating ones developed, and these were all anomalous. 7. The dwarfed and anomalous growth of seedlings only rarely occurred in parts other than the epicotyledonary axis and its appendages. New shoots induced from axillary buds were free from dwarfed and anomalous characters.