Ecophysiological role of mucilaginous seed coat on germination and seedling growth of Balangu (Lallemantia royleana) imposed to drought and salinity stress

It seems mucilaginous seed coat is an aspect of plants evolutionary adaptation to desert environments. Because of mucilage production, seed coat of Balangu Shirazi (Lallemantia royleana) absorbs water multiple times more than of its initial weight. To determine the possible role of mucilaginous seed coat, two mucilaginous (M) and demucilaged (DM) seeds were examined in two separate experiments of drought with six levels (0 as control, -0.1, -0.2, -0.3, -0.4,and -0.5 MPa) and salinity with six levels (0 as control, 2, 4, 6, 8, and 10 ds.m-1) through factorial experiment as completely randomized design with three replications of 25 seeds. Germination of demucilaged seeds significantly was higher than mucilaginous seed in drought trial; though in salinity stress, there was no significant difference between germination of mucilaginous and demucilaged seeds. Mean germination time (MGT) in mucilaginous seeds was higher than the demucilaged seeds in both salinity and drought stresses. In salinity experiment, length of root, stem and stem/root length ratio in mucilaginous seed was higher than the demucilaged seed significantly; while there was no any differences in drought stress. Interaction of seed with drought was not significant but there was significant interaction between seed and salinity.