Application of Embryo Rescue Technique in Juglans regia L. x J. nigra L. Hybridization

Abstract

Embryo culture were used to produce inter specific walnut hybrid plants between Juglans nigra L. and J. regia L. Developed ovaries were collected from J. rejia female flowers which were pollinated with J. nigra pollen grain by high dusting on a mature tree. In order to isolate embryos, exocarps were aseptically removed. Isolated embryos from ovules at different developmental stages were transferred to the different kind of growth-regulators hormone free media (MS, Half-MS, MS and Half-MS supplemented with 1 mg/l BA +0.1 mg/l NAA) for embryo development and germination. There was a significant difference between media for embryo germination α= 0.05 level. Highest percentage of embryo germination was observed in MS hormone free medium (13.7%). Because of long period required for embryo development, isolation of embryo less than 45 days old embryos were impractical. There were a highly significant difference between age of embryos for embryo germination α= 0.01 level. Embryo with more than 45 days old germinated and produced plants on all applied media. Highest germination rate were observed on cross-pollinated embryos which was isolated from 90 old ovaries. Before being transferred to the potting soil and green-house, plantlets sub cultured in the same medium within jars. Thirteen successful acclimatized plantlets were transferred to the field.