Cadmium toxicity in African yam bean (Sphenostylis stenocarpa (HOCHST. EX A.RICH.) HARMS genotypes | Toksičnost kadmija za izbrane genotipe afriškega gomoljastega fižola(Sphenostylis stenocarpa (HOCHST. EX A.RICH.) HARMS

anglais. The aim of the study was to investigate the growth responses of African yam bean (Sphenostylis sternocarpa (Hochst. ex A. Rich.) Harms (AYB) to cadmium pollution. Top garden soil (0 – 10 cm) was obtained as pooled and polluted with cadmium (as CdCl2) at the rate of 12 mg kg-1, which is equivalent to 3 times the ecotoxicological screening value of Cd. The polluted soils were made ready for use 3 days later. Nine selected AYB accessions (TSs-87, TSs-89, TSs-90, TSs-91, TSs-92, TSs-93, TSs-94, TSs-95, and TSs-96) were pre-soaked for 30 minutes and then sown in the polluted and unpolluted soils. Data collected were subjected to ANOVA, and means were separated at 95 % confidence interval. Results showed that incidence of cadmium pollution significantly delayed seedling emergence in all tested AYB accessions by at least one day (p < 0.05). Despite exposure to Cd, TSs-96 attained 50 % emergence faster than other accessions. Although there were general reductions in yield due to exposure to Cd, TSs-92 showed the least percentage yield reduction (50 %), compared to 74 % yield reduction in TSs-93, thereby suggesting a comparatively better yield capacity compared to the other test accessions. Overall, decrease in total chlorophyll content seems to be the major reason of injury in Cd-exposed plants.

slovène. Namen raziskave je bil preučiti rastni odziv afriškega gomoljastega fižola (Sphenostylis sternocarpa (Hochst. ex A. Rich.) Harms (AYB) na onesnaženje tal s kadmijem. Vzorčena je bila vrhnja plast vrtnih tal (0 – 10 cm), onesnažena s kadmijem (kot CdCl2) v velikosti 12 mg kg-1, kar je trikratni ekvivalent priporočene ekotoksikološke vrednosti za Cd. Onesnažena tla so bila pripravljena za poskus v treh dneh. Izbranih je bilo devet akcesij AYB (TSs-87, TSs-89, TSs-90, TSs-91, TSs-92, TSs-93, TSs-94, TSs-95, in TSs-96), katerih semena so bila predhodno namočena za 30 minut in potem posejana v onesnažena in neonesnaženea tla. Zbrani podatki so bili ovrednoteni z ANOVA, kjer so bila poprečja ločena pri 95 % intervalu zaupanja. Rezultati so pokazali, da je onesnaženje s kadmijem značilno zamaknilo vznik kalic AYB pri vseh preiskušenih akcesijah najmanj za en dan (p < 0,05). Kljub izpostavitvi Cd, je akcesija TSs-96 dosegla 50 % kalivost hitreje kot vse ostale. Kljub splošnemu upadu pridelka zaradi izpostavljenosti kadmiju, je akcesija TSs-92 pokazala najmanjši upad pridelka (50 %), v primerjavi s 74 % upadom pri akcesiji TSs-93, kar kaže na njeno boljšo primerjalno sposobnost prilagoditve v primerjavi z drugimi genotipi. Na splošno je bil glavni razlog poškodb zaradi Cd pri vseh izpostavljenih rastlinah upad celokupne vsebnosti  klorofila.