Cytogenetic analysis and differential response of rye-introgressed bread wheat genotypes for cold tolerance.

Twenty three rye-introgressed bread wheat genotypes, two triticale parents, one rye and 2 wheat checks were examined for tolerance to cold stress and were subjec ted to cytogenetic analysis. On the basis of colorimetric estimation of the intensity of extracted formanzan, rye was found to be the most cold tolerant cereal, while five genotypes, viz., TW9321, RL75/83, RL6-3-4, TW9308 and TW9328 together with two triticale genotypes were found to be cold tolerant. Cold tolerance is suppressed to a great extent in triticale, making it difficult to transfer high levels of cold tolerance to wheat. The derivatives, TW9308 and TW9321 carried 7R(7D) substitution while the derivative TW9328 carried 6R (60) substitution, indicating the association of cold tolerance with 6R and 7R chromosomes of rye.