Seed germination prediction of osmotic-stressed safflower (Carthamus tinctorius L.) at different temperatures using hydrotime analysis

The hydrotime analysis can predict the germination of plants at reduced water potential (ψ). The effects of reduced ψ on seed germination properties in three safflower cultivars including Padideh, Faraman and Isfahan cultivars at ۱۰, ۲۰ and ۳۰ ºC were analyzed using the hydrotime model. Five ψ values (۰, -۰.۳, -۰.۶, -۰.۹ and -۱.۲ MPa) prepared in polyethylene glycol ۶۰۰۰ (PEG) solutions were used in the experiment. The results indicated that all three tested cultivars had the highest germination rate at ۳۰º C and better tolerance to osmotic stress at ۲۰º C. At ۲۰º C, Faraman cultivar had the lowest medium base water potential [ψb(۵۰)]. The standard deviation of ψb (σψb) among cultivars and temperatures could be as high as ۰.۵۲ MPa for the Faraman cultivar at ۲۰º. Three tested cultivars had statistically different hydrotime constant (θH) at ۱۰º C. The lowest ψb(۵۰) for achieving ۵۰% germination at ۱۰º C was seen in the Isfahan cultivar, and at either ۲۰º C or ۳۰º C was seen in Faraman and Padideh cultivars. The suppressing effect of drought stress on seed germination was greater in Padideh and Faraman cultivars than that in the Isfahan cultivar. Overall, applying of hydrotime model allowed identifying osmotic stress-tolerant cultivars such as Isfahan during germination; and which might be helpful to seed germination prediction and providing more accurate information for sowing time of safflower.Abbreviations: ψ (water potential); PEG (polyethylene glycol); ψb(۵۰) (medium base water potential); θH (hydrotime constant); σψb (standard deviation of ψb); MGT (mean germination time); FGP (final germination percentage).

کلیدواژه ها:

Carthamus tinctorius L ، germination rate ، hydrotime constant ، water potential