The Effect of Drought Stress on Germination and Heterotrophic Seedling Growth Characteristics of Lentil (Lens culinaris Medik)

Drought stress in germination stage is one of most important factor that limit yield and growth of lentil in Iran. The heterotrophic seedling growth can be considered as the product of three components: initial seed weight، the fraction of seed reserves which are mobilized، and the conversion efficiency of mobilized seed reserves to seedling tissues. In order to investigate the effect of drought stress on percentage and rate of germination and seedling growth components، a factorial experiment was conducted based on randomized completely design (RCD) with three replications. The experimental factors were included three lentil cultivars (Robat، Kimia، Gachsaran) and five levels of drought stress (0، -3، -6، -9، -12 bar of polyethylene glycol 6000). The results showed that with increasing drought stress، percentage and rate of germination percentage was decreased to zero in the osmotic potential of -12 bar. Although significant difference was not observed in germination percentage in drought stress levels between different cultivars، but difference in germination rate was significant. The rank of cultivars was Robat> Gachsaran> Kimia in germination rate. The inverse linear relationship was made between drought stress levels and seedling growth components. More seed reserve depletion in Robat and Gachsaran lead to more seedling dry weight of two cultivars in compare to Kimia cultivar that had more conversion efficiency. Thus efforts to improve germination and seedling growth in lentil breeding programs should focus on improvement of component of mobilized seed reserves.