Effect of terminal drought tension on seed germination indices and photosynthetic pigments of maternal genotypes safflower (Carthamus tinctrorius L.)

Drought tension is one of the most important tensions in reducing germination of plants. In order to evaluate the effect of drought tension on seed germination characteristics and photosynthetic pigments maternal genotypes of safflower, a factorial experiment based on completely randomized design with four replications was conducted at seed technology laboratory of Shahed University in 2015. The examined factors included seeds produced in two levels of optimal irrigation and application of drought tension after flowering stage on mother plant and four genotypes of Safflower including Soffeh Isfahan, Goldasht, Mexico12 and Line 411. The results showed that genotype and drought tension had significant effect on under investigation traits. In addition, the results showed that drought tension increased the traits average length of germination time, seedling length, chlorophyll b content and carotenoid content and reduced other assessed traits. The seeds produced in conditions of drought tension on rootstock genotype Mexico 12 had the highest percentage of germination (94.59 percent), length of seedling vigor index (202.44), seedling vigor weighted index (8.51) and the amount of chlorophyll b (0.42 milligram per gram wet weight). In general, application the terminal drought tension on the mother plant of the investigated genotypes reduced seed germination characteristics and seedling growth of safflower genotypes. Totally, seed of those cultivars that their mother plant encountered with drought tension is not suitable for planting in areas with irrigation constraints or drought probability in these areas.