FACTORS INFLUENCING SOMATIC EMBRYOGENESIS AND PLANTLET REGENERATION IN PECAN, CARYA ILLINOENSIS

Somatic embryogenesis and plantlet regeneration were further characterized in pecan, [Carya illinoensis (Wangenh) C. Koch]. The effects of zygotic embryo explanting time and auxin type during conditioning were examined. Embryogenic response was restricted to a narrow developmental period. Maximum embryogenesis was observed at 15 weeks post-pollination, which corresponded to the period of rapid cotyledon expansion. Auxin type and concentration significantly affected percent embryogenesis and embryo form, but not embryogenic efficiency. Embryos induced on lower levels of NAA exhibited stronger, more defined apices than those induced on medium with 2,4-D. Murashige and Skoog (MS) medium was more effective for embryo germination than Woody Plant Medium (WPM). A 5-week cold treatment in conjunction with desiccation enhanced somatic embryo conversion to plants.