تأثیر تنش خشکی مرحله زایشی بر ویژگی‌های جوانه‌زنی بذر ژنوتیپ‌های بومی و اصلاح‌شده برنج (Oryza sativa)

In order to study drought stress effect at the reproductive stage on seed germination characteristics of seven rice genotypes, an experiment was carried out at Sari Agricultural Sciences and Natural Resources University in 2014. This study was conducted on drought-stressed seeds and seeds grown under normal conditions. The results of orthogonal mean comparison among non-stressed seeds showed that local genotypes had a lower germination index, germination rate, water percentage of seedling tissue, shoot length and root dry weight than the improved genotypes. Among stressed seeds, however, local genotypes had a higher germination index and germination rates than those of improved genotypes. Comparison of non-stressed seeds of susceptible and tolerant genotypes indicated that susceptible genotypes had a higher germination index, germination rate and germination percentage than tolerant genotypes. On the other hand, the comparison of the stressed seeds of susceptible and tolerant genotypes revealed that drought stress increased the time to 10, 50, 90 and 95% germination, water percentage of seedling tissue and plantlet length in susceptible genotypes, which were higher than those of tolerant genotypes. In conclusion, it seems that drought stress at reproductive stage has a significant effect on germination characteristics of the plant’s following generation. However, their responses are different, depending on the level tolerance of the genotype to stress and genetic origin. Highlights:  1-  Drought stress at reproductive stage has a significant effect on germination characteristics of the following generation of the rice plant. 2-  Among stressed seeds, local genotypes have a higher germination index and germination rates than those of the improved genotypes. 3-  Drought stress increases the time of germination in susceptible genotypes, which is higher than that in the tolerant genotypes.