The responses of growth, photochemical and antioxidant defence of sa ower species (Carthamus oxyacantha M. Bieb. and Carthamus tinctorius L. exposed to nickel (Ni) toxicity were investigated in the study. Fourteen-day-old seedlings were treated with excessive Ni levels [control, 0.50, 0.75 and 1.00 mM] for 7 days. The results of chlorophyll a uorescence indicated that toxic nickel exposure led to changes in speci c, phenomenological energy uxes and quantum yields in thylakoid membranes, and activities of donor and acceptor sides of photosystems. These changes resulted in a signi cant decrease in the photosynthetic performance of the species, but these negative effects of Ni were not in a level to destroy the functionality of the photosystems. At the same time, toxic Ni affected membrane integrity and the amount of photosynthetic pigments in the antenna and active reaction centers. Additionally, the accumulation of Ni was higher in roots than in stem and leaves for both species. Depending on Ni accumulation, a signi cant reduction in dry biomass of root and shoot was observed in both species.Two species could probably withstand deleterious Ni toxicity with better upregulating own protective defence systems such as antioxidant enzymes. Among of them, SOD and POD activities were increased with increasing Ni concentrations. The POD activities of both species were most prominent and consistently increased in toxic Ni levels and may be protected them from damaging effect of H 2 O 2 . When all results are evaluated as a whole, Carthamus species produced similar responses to toxicity and also both species have Bioconcentration (BCF) and Bioaccumulation factors (BF) > 1 and Translocation factor (TF) < 1 under Ni toxicity may be regarded a good indication of Ni tolerance. Consequently, it is possible to use the Carthamus species in the remediation (phytostabilization) of soils contaminated with nickel, because of their roots accumulating more nickel.

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İki yakın akraba tür olan Lomelosia argentea ve Lomelosia polykratis türlerinin anatomik özellikleri ilk defa bu çalışmada incelenerek farklılıklarının ortaya konulması ve taksonomik çalışmalarda yaşanabilecek potansiyel karışıklıkların önüne geçilmesi amaçlanmıştır. Bu amaçla mikroskobik gözlemler için parafin metodu kullanılarak türlerin kök, gövde ve yapraklarından HM310 Mikrotom yardımıyla kesitler alınmıştır. Alınan enine kesitler safranin ve fast-green boyaları ile boyandıktan sonra Leica DM750 ışık mikroskobunda incelenmiş ve ölçümleri alınarak fotoğraflanmıştır. L. argentea ve L. polykratis türlerinin bazı benzer anatomik özellikleri bulunmasına rağmen, çeşitli anatomik farklılıkları olduğu da ortaya konulmuştur. Kökte korteks parankiması, floem ve trake; gövdede epidermis, korteks parankiması, floem, öz parankiması, trake ve kutikula; yaprak için üst ve alt kutikula, üst epidermis, trake ve mezofil ölçüm sonuçları, L. polykratis ile L. argentea bitkileri karşılaştırıldığında istatistiksel olarak anlamlı bulunmuştur.

The responses of growth, photochemical and antioxidant defence of safflower species (Carthamus oxyacantha M. Bieb. and Carthamus tinctorius L. exposed to nickel (Ni) toxicity were investigated in the study. Fourteen-day-old seedlings were treated with excessive Ni levels [control, 0.50, 0.75 and 1.00 mM] for 7 days. The results of chlorophyll a fluorescence indicated that toxic nickel exposure led to changes in specific, phenomenological energy fluxes and quantum yields in thylakoid membranes, and activities of donor and acceptor sides of photosystems. These changes resulted in a significant decrease in the photosynthetic performance of the species, but these negative effects of Ni were not in a level to destroy the functionality of the photosystems. At the same time, toxic Ni affected membrane integrity and the amount of photosynthetic pigments in the antenna and active reaction centers. Additionally, the accumulation of Ni was higher in roots than in stem and leaves for both species. Depending on Ni accumulation, a significant reduction in dry biomass of root and shoot was observed in both species. Two species could probably withstand deleterious Ni toxicity with better upregulating own protective defence systems such as antioxidant enzymes. Among of them, SOD and POD activities were increased with increasing Ni concentrations. The POD activities of both species were most prominent and consistently increased in toxic Ni levels and may be protected them from damaging effect of H2O2. When all results are evaluated as a whole, Carthamus species produced similar responses to toxicity and also both species have Bioconcentration (BCF) and Bioaccumulation factors (BF) > 1 and Translocation factor (TF) < 1 under Ni toxicity may be regarded a good indication of Ni tolerance. Consequently, it is possible to use the Carthamus species in the remediation (phytostabilization) of soils contaminated with nickel, because of their roots accumulating more nickel.