Abstract
The effects of salinity were studied on root morphology and seedling growth in thirty five day old Gossypium hirsutum, Kosteletzkya virginica and Thespesia populnea under different concentrations of sea salt solution i.e. non saline control (ECiw: 0.4 dS.m-1 ), 0.5% sea salt (ECiw: 6.2 dS.m-1 ), 1.0% sea salt (ECiw: 12.95 dS.m-1 ). Results showed that primary root length was reduced in K. virginica at 1.0% sea salt, while it remained almost unaffected in the other two plants at this salinity in comparison to control. Number of secondary roots increased in G. hirsutum and T. populnea but in K. virginica they show a slight decrease. All the three plants showed promotion in the length of secondary roots at 0.5% salinity. Number of tertiary roots was enhanced in T. populnea at 0.5% salinity level, whereas the other two plants exhibit inhibition of tertiary roots. Root biomass was increased in G. hirsutum at 0.5% salinity but decreased at higher salinity. K. virginica and T. populnea showed decrease with the increasing salinity. Fresh and dry shoot biomass and plant height showed a gradual decrease in response to increasing salinity in all the three species. The number of leaves decreased gradually in K. virginica and T. populnea as the salinity of the rooting medium increased, whereas, in G. hirsutum, the number of leaves decreased under saline condition but the number of leaves were more or less same under two salinity levels. Leaf area per plant of K. virginica and G. hirsutum gradually reduced with increasing salinity. In T. populnea leaf area increased at 0.5% salinity and decreased at 1.0% salinity level. T. populnea showed more uptake of Na+ and K+ under non saline condition as compared to the other two plants. Uptake of Na+ increased with increasing salinity in all the three plants. K+ concentration increased in roots of T. populnea and G. hirsutum and decreased in K. virginica at 0.5% salinity. At 1.0% salinity level K+ concentration substantially decreased in all the three plants. The results showed that K. virginica was comparatively more tolerant under saline condition, where as G. hirsutum showed the comparatively least tolerance. Over all salt tolerance during growth of above mentioned three plants at higher level of salinity show that G. hirsutum was more tolerant, where as K. virginica showed the least tolerance at seedling stage. Key Words: Root morphology, seedling growth, Gossypium hirsutum, Kosteletzkya virginica, Thespesia popul
