Investigating the freezing tolerance of wild oat (Avena lodoviciana L.) genotypes using electrolyte leakage test

To evaluate the freezing tolerance of seven wild oat genotypes (DR4, NR11, SOR1, STR1, ZR5, SM, SKh), a factorial experiment was performed based on completely randomized design with three replications at Ferdowsi University of Mashhad, Faculty of Agriculture in 2009. Amongst these wild oat genotypes, two of them (SM, SKh) were reported as herbicide susceptible, while herbicide resistance had been reported for the rest of them. Wild oat genotypes were exposed to seven freezing temperatures (-3, -6, -9, -12, -15,-18 and -21°C). Potted plants were grown in natural conditions and maintained for acclimation until 3-4 leaf stage and then, the plants were subjected to freezing temperature (FT) regimes using a thermo-gradient freezer. Plant electrolyte leakage, lethal temperature for 50% of samples based on electrolyte leakage (LT50el) and temperature for 50% dry weight reduction (RDMT50) were determined. Results showed that the effect of frost temperature, and genotype on the rate of electrolyte leakage and LT50el of genotypes was significant (P <0.01). Reducing the temperature less than - 9 °C increased electrolyte leakage in all genotypes. Among wild oat genotypes, SM and Skh showed the greatest and lowest cold tolerance according to LT50el and RDMT50, respectively. While this experiment confirmed differences in freezing tolerance amongst wild oat genotypes based on their geographical origins, results showed that herbicide resistance in wild oat may lead to change some other plant characteristics such as cold tolerance. So that based on these results, wild oat herbicide resistant genotypes (DR4 NR11, SOR1, STR1, and ZR5) had greater LT50el values comparing with Khoozestaan sensitive genotype (Skh).