Effect of seed position on the spike on salinity tolerance of barley (Hordeum vulgare L.) seeds at germination and early seedling growth

Seed position on mother plant can affect seed size, color and its germination in several plant species. In order to study the effect of seed position in spike on salinity resistance of barley, a factorial experiment based on RCBD was conducted with two factors including seed position (top, middle and bottom of the spike) and salinity (0, 10, 20, 40, 80, 160, 320 and 640 mM NaCl). Results showed that the interaction between seed position and salinity effects on germination percentage was significant and seeds of the middle of the spike, which were larger than others, had the highest germination at all salinity levels. The estimations of the three-parameter logistic model also showed that the middle seeds had greater salinity tolerance compared to the seeds from the top and bottom of the spike. Increasing salinity significantly delayed seed germination and reduced root and shoot growth, while seed position did not affect these parameters. Concerning to the higher germination percentage of seeds in the middle of the spike (large seeds) under salinity stress, they can be employed for increasing emergence percentage in saline soils.