Amin Abbasi

In order to evaluate physiological and biochemical response of bread wheat (Sardari, Rizhav, Baran) and durum wheat (Saji, Rascon, Gerdish) to cold stress under conventional and conservation agriculture systems, a split split plot experiment based on RCBD with three replications was conducted during two years (2018-19 and 2019-20). Three different sowing dates (Sept., Oct., and Nov.) were located in main plots and two tillage methods (conventional and conservation) were considered in sub plots and six wheat cultivars (Sardari, Rizhav, Baran, Saji, Rascon and Gerdish) were located in sub-sub plots. All of the plots were irrigated after different times of sowing. Results indicated in conservation tillage methods, light stage of photosynthesis was improved with redoction of Qb, PQ, Cyt b6f and PC and transfer electron to the acceptor sute of PSI. Under conservation agriculture system photosynthesis pigments and electron transfer effecincy were improved. KJ, JI and IP stages were affected under conservation agriculture system. Photosynthesis efficiency with decreasing of ABS/RC and Fo/Fm and increasing of Fv/Fm and ETo/RC in the first sowing time under zero tillage treatment in all wheat cultivars improved. Sardari and Baran, in comparison to other cultivars were good acclimated and with more production of SOD, reduced the content of H2O2 and MDA under zero tillage system. Grain yield was not affected by tillage methods. Grain yield of first date of sowing was 20-27 % and 11-47% more than other treatments during first and second years, respectively.