Effects of partial endosperm removal on embryo dormancy breaking and salt tolerance of Hordeum spontaneum seeds

Seed damage is a common phenomenon in nature and in agricultural production. In this experiment, partial endosperm removal from wild barley (Hordeum spontaneum) caryopses, sampled from three ecotypes originated from xeric environments in Israel, was conducted. The aim was to examine seed dormancy and germination states in damaged caryopses and salt tolerance of young seedlings derived from them. Six treatments were made: (1) control seeds with intact caryopses; (2-4) removal of 0.25, 0.5, and 0.75 of the length of intact caryopses; (5) transection at the points, at which the endosperm and embryo meet; and (6) slitting of endosperm opposite the embryo. A significant negative correlation was found between germination percentage (dormancy release) and the relative distance from the dissection point to embryo. Partial removal of the endosperm could accelerate dormancy release. Seedling salt tolerance was assessed by the ratio of root or coleoptile length in a seedling grown in 100 or 200 mM NaCl solution to that of a seedling grown in water. The seedling salt tolerance was positively correlated with the removed portion of the seed endosperm. For each level of endosperm removal, the salt tolerance to 200 mM NaCl of the seedlings derived from the Dead Sea ecotype was higher than those from both the Sede Boker and the Mehola ecotypes. The results suggest that partial damage to seed endosperms in natural conditions may play a role in increasing the phenotypic plasticity of germination and salt tolerance.